ALBERT R. MANN

   

‘s,s NEW YorK STATE COLLEGES
OF ee
AGRICULTURE AND HoME EcoNomiIcs

AT

CORNELL UNIVERSITY

 

 

” ( EVERETT FRANKLIN PHILLIPS
BEEKEEPING LIBRARY
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————

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LIBRARY °+,* 4

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“Tin
TECHNICAL Series, No. 18.
U. Ss. DEPARTMENT OF AGRICULTURE,
BUREAU or EINTOMOLOGY.
Li Oo. HOWARD, Entomologist and Chief of Bureau.

 

+
THE ANATOMY OF THE HONEY BEE.
rialeek id Mereclaetaag — Pape 2 OY -

R. EL SNODGRASS, .
' Agent and Expert.

_Issuep May ‘28,1910.

 

WASHINGTON:
FOL ENMENT PRINTING (OFFIOE.

1910.
TECHNICAL SERIES, No. 18.

U. S. DEPARTMENT OF AGRICULTURE,
BUREAU OF ENTOMOLOGY.
L. O. HOWARD, Entomologist and Chief of Bureau.

Castee| (znd 21 BA ms. ith) 3s be/ )

if

THE ANATOMY OF THE HONEY BEE.

BY

R. E, SNODGRASS,
Agent and Expert.

Issurp May 28, 1910.

 

WASHINGTON:
GOVERNMENT PRINTING OFFICE,

1910.
QL
564
S67

AS

 

BUREAU OF ENTOMOLOGY.

L. O. Howarp, Entomologist and Chief of Bureau.
Cc. L. Martatr, Assistant Entomologist and Acting Chief.in, Absence of Chief.
R. S. Ciirron, Executive Assistant.
W. F. Taster, Chief Clerk.

PF. H. Cuirtenpen, in charge of truck crop and stored product insect investigations,
A. D. Hopkins, in charge of forest insect investigations,

W. D. Hunter, in charge of southern field crop insect investigations.

F. M. Wesster, in charge of cereal and forage inscct investigations.

A. L. QUAINTANCE, in charge of deciduous fruit insect investigations.

BE. F. Pures, in charge of bee culture.

D. M. Rocers, in charge of preventing spread of moths, field work.
Roiia P. Currie, in charge of editorial work.
MaBeEL CotcorD, librarian.

INVESTIGATIONS IN BEE CULTURE.

BE. F. PuHiuies, in charge.

G. F. Waits, J. A. NELSon, B. N. Gates, R. E. Snoperass, A. H. McCray, agents
and cxeperts.

ELLEN DASHIELL, preparator.

JeSsIz E. Marks, cilcrk.

T. B. Symons, collaborator for Maryland,

H. A. SURFACE, collaborator for Pennsylwania.

J. C. C. Pricr, collaborator for Virginia,

2
LETTER OF TRANSMITTAL.

U. S. Department or AGRICULTURE,
Bureau or Entomoxocy,
Washington, D. C., October 19, 1909.

Sir: I have the honor to transmit herewith a manuscript entitled
“The Anatomy of the Honey Bee,” by Mr. R. E. Snodgrass, agent
and expert, of this Bureau. It embodies the results of detailed
studies made by Mr. Snodgrass and should prove of value as bring-
ing to the bee keeper reliable information concerning an insect of
such great economic importance, and also as furnishing a sound
basis in devising new .and improved practical manipulations. I
recommend its publication as Technical Series, No. 18, of the Bureau
of Entomology.

Respectfully, L. O. Howarp,
Entomologist and Chief of Bureau.
Hon. James Wixson,
Secretary of Agriculture.
CONTENTS.

Fe Introd Wetionls cicada San aeacinenbe ae RARE oe cee eeees sees
II, General external structure of insects. ........-.-..-222-2-2-0---- 20 eee ee
III. The head of the bee and its appendages......-.....---------------
1. The structure of the head. .-......-..-.-.2.--2--------------

2. The antenne and their sense organs.........-....-------------

3. The mandibles and their glands.............-..--.-----------

A, THe prob O8 CIB! 6 iro svenevse cts aveisto dics tree aMnGRa nee USS eae

by Thevepipharya x) oscacarecsudiedee Geeei es cian cte ies canes

IV. The thorax and its appendages. ...........--2---22--2-5-------2-----
1. The structure of the thorax...........-..-2----+---------------

2. The wings and their articulation. ...-.-...---- pebe donee sulscins

Ai PNG SBS os So oiasaptrcis aca nele aes lava ose eset a REE Ee Re ata

V. The abdomen, wax glands, and sting..........---..---------------
VI. The alimentary canal and its glands..................-------222+00+-
1. The general physiology of digestion, assimilation, and excretion.

2. Thesalivary: Clan ds a sc oxverdacenmeomiacka Gude heotaccccasaeisee

3. The alimentary canal..........-.-.2-.---202-0-- 22202222 e ee eee

VIE. The:circulatory systemic s.2c.6cvecinne gececiedcakes se ewes aneee
VIIE. The-respiratory system... «2.225 seccdseecaresseee bees sere eee essere
IX. The fat body and the cenocytes.........-.---------++-2----------------
X. The nervous system and the eyes....-.-.-.--2-2---2-2----2-2-0-2---
AI. ‘The reproductive system: fs... 4csenstees acces sy ee seuss eesensseess
1s. Thewmale-oroatists. ooo ceccctcewscec cade op eee BAS ERR Ses

2. TINO TEMS @ ORGANS <2 :js.zacccccrtaiedaccieud sicisiaid, Faerie one Sema Ses
Explanation of the symbols and letters used on the illustrations.....-.-
Bibhopra pl yi enseice saccharate RiGee aan Reon e a aees
Index
Fia.

Nook wN eR

10.
11.
12.
13.
14.
15.
16.

17.
18.
19.
20.
21.
22.

23.
24,
25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
41.

ILLUSTRATIONS.

. Median longitudinal section of body of worker...
. Diagram of generalized insect embryo........----
. Example of generalized insect mouth parts.......
. Diagram of generalized thoracic segment.........
. Typical insect leg. .......- Pave beats oneal AS AS
. Diagram of generalized insect wing and its articulation...........---.
. Diagram of terminal abdominal segments of a female insect and early

stage in development of gonapophyses.........

. Example of a swordlike ovipositor -............--
. Head of worker bee .. 2. .cssesceseceaseeeeveess

Heads of worker, queen, and drone.............-

Median longitudinal sections of heads of worker and drone.....-..-.--

Antennal hairs and sense organs.............- ets
Mandibles of worker and drone. ...--...-...----
Internal mandibular gland of worker............-
Mouth parts of worker.........--.--------------

Median section through distal half of mentum and base of ligula of

Epipharynx and labrum of worker.........-...-
Sense organs of epipharynx.........-...-..------

Median longitudinal section of head of worker....

Dorsal view of ventral walls of body of worker..............-..--.----

Thorax of worker.......-. Siiouseamsmacdmiencaths
Lateral view of mesotergum of worker.........-..
Thoracic terga of worker....-..-...-------------
Upper part of left mesopleurum of worker... . ..
Wings of Hymenoptera.............---.--------
Basal elements of wings of Hymenoptera ......-
Median section through thorax of drone.........

Internal view of right pleurum of mesothorax of drone. .......-..--.-

Legs of worker, queen, and drone.........-...--
Claws and empodium of foot of worker.....-..--
Tarsal claws of worker, queen, and drone.......
Lateral view of abdomen of worker

Sixth abdominal sternum of worker, queen, and drone
Semidiagrammatic view of left side of sting of worker

Ventral view of sting of worker................
Section of small piece of wall of poison sac
Sections of alkaline gland of sting. .............
Details of sting of worker. .....................
Tip of abdomen of worker with left side removed

6

25
25
27
29
30
36
40
42
43

51
52
52
53
54
56
57
58
60
61
64
65
67
68
69
70
70
70
72
75
76
79
79
81
82
Fig. 42.
43.
44,
45.
46.
47.
48.
49.
50.
51.
52.
53.
54.
55.
56.
57.

ALLUSERATIONS.

Alimentary canal of worker.............2..2--2-2--ee cece cere eee
Details of pharyngeal and salivary glands .....-...-----------------
Honey stomach of worker, queen, and drone ..........-----------+--
Longitudinal section of honey stomach and proventriculus of queen -
Histological details of alimentary canal of worker .....-...----------
Dorsal diaphragm of drone, from one segment ....-..-.-------------
Small part of dorsal diaphragm of drone .......-.------ iiaeo geiavoeaiaeevs
Pericardial chamber of one segment in worker ......-.-.--------+-+
Tracheal system of worker ..........-..--..20-220-ee cece reese notes
Tracheal system of worker .......-...--.---20-¢+2e eee eee ee eee eters
Nervous system of worker......-....--------+-+-- syd in Stepan Rechte
Brain and subcesophageal ganglion of worker iiSatadeciagnsc ice SAAS
Horizontal section of compound eye and optic lobe of worker ....---
Histological details of compound eye of worker .......-..-.----------
Reproductive organs of drone ......-.--------+- 222222 ee eee eee eee
Reproductive organ and sting of queen . . .-- GRO Atha CRA
% i dqqd) wuewmopqe jo smSsviydelp [e1zU9A pus [Bs10p
(oF) v}108 pues GQ ) J1Vaqy JO Zuystsuoo jassaa [vsiop pus ‘(ydqA pus Y ! : Le ae
*(QI-T ‘ogp4y) Waysks [Boyoes} ‘(OupL-TdO) ma}sfs snoAreu SurMoys ‘1a_xI0M Jo Apoq eayyue JO WOTJDaS [VdT,IOA ‘UBIPSMT ‘[eUTPN}{su0T—T “I

wae aS

Na

a

 
THE ANATOMY OF THE HONEY BEE.

I. INTRODUCTION.

The anatomy of the honey bee has been for years a subject of much
interest to those engaged in bee keeping both for pleasure and for
profit. This interest is due not only to a laudable curiosity to know
more of the bee, but to the necessity of such information in order
to understand fully what takes place in the colony. All practical
manipulations of bees must depend on an understanding of the be-
havior and physiology of bees under normal and abnormal circum-
stances, and those bee keepers who have advanced bee keeping most
by devising better manipulations are those, in general, who know
most of bee activity. In turn, a knowledge of bee activity must rest
largely on a knowledge of the structure of the adult bee.

Studies on the anatomy of the bee have not been lacking, for
many good workers have taken up this subject for investigation.
The popular demand for such information, however, has induced
untrained men to write on the subject, and most accounts of bee
anatomy contain numerous errors. This is probably to a greater
extent true of the anatomy of the bee than of that of any other
insect. Frequently the illustrations used by men not trained in
anatomical work are more artistic than those usually found in papers
on insect anatomy, and they consequently bear the superficial marks
of careful work, but too often it is found that the details are in-
accurate. It has therefore seemed the right time for a new presenta-
tion of this subject based on careful work.

The drawings given in the present paper are original, with the
exception of figures 12, 54, and 55, and have been prepared with
a thorough realization of the need of more accurate illustrations of
the organs of the bee, especially of the internal organs. Mistakes
will possibly be found, but the reader may be assured that all the
parts drawn were seen. Most of the dissections, moreover, were
verified by Dr. E. F. Phillips and Dr. J. A. Nelson, of this Bureau,
before the drawings were made from them. An explanation of the
abbreviations and lettering is given on pages 139-147.

It is hoped that the work will furnish the interested bee keeper
with better information on the anatomy of the bee than has hereto-
fore been offered to him, that it may provide a foundation for more
detailed work in anatomy and histology, and, finally, that it will be

9
10 THE ANATOMY OF THE HONEY BEE,

of service to future students of the embryology and physiology of
the bee. With this last object in view the writer has tried to sum
up under each heading the little that is at present known of insect
physiology in order to bring out more clearly what needs to be done
in this subject.

II. GENERAL EXTERNAL STRUCTURE OF INSECTS.

When we think of an animal, whether a bee, fish, or dog, we uncon-
sciously assume that it possesses organs which perform the same vital
functions that we are acquainted with in ourselves. We know, for
example, that an insect eats and that it dies when starved; we realize
therefore that it eats to maintain life, and we assume that this involves
the possession of organs of digestion. We know that most insects see,
smell, and perform coordinated actions, and we recognize, therefore,
that they must have a nervous system. Their movements indicate to
us that they possess muscles. These assumptions, moreover, are en-
tirely correct, for it seems that nature has only one way of producing
and maintaining living beings. No matter how dissimilar two
animals may be in shape or even in fundamental constitution, their
life processes, nevertheless, are essentially identical. Corresponding
organs may not be the same in appearance or action but they accom-
plish the same ends. The jaws may work up and down or they may
work sidewise, but in either case they tear, crush, or chew the food
before it is swallowed. The stomach may be of very different shape
in two animals, but in each it changes the raw food into a soluble and
an assimilable condition. The blood may be red or colorless, con-
tained in tubes or not, but it always serves to distribute the prepared
food which diffuses into it from the alimentary canal. The situa-
tion of the central nervous system and the arrangement of its parts
may be absolutely unlike in two organisms, but it regulates the func-
tions of the organs and coordinates the actions of the muscles just
the same. ;

Hence, in studying the honey bee we shall find, as we naturally
expect to find, that it possesses mouth organs for taking up raw food,
an alimentary canal to digest it, salivary glands to furnish a digestive
liquid, a contractile heart to keep the blood in circulation, a respira-
tory system to furnish fresh oxygen and carry off waste gases, ex-
cretory organs for eliminating waste substances from the blood, a
nervous system to regulate and control all the other parts, and, finally,
organs to produce the reproductive elements from which new indi-
viduals are formed to take the places of those that die.

The study of anatomy or the structure of the organs themselves
is inseparably connected with a study of physiology or the life

. functions of the animal. While physiology is a most interesting
and important subject, and, indeed, in one sense might be said to be
GENERAL EXTERNAL STRUCTURE OF INSECTS. 11

the object of all anatomical research, yet the mere study of the
structure of the organs alone, their wonderful mechanical adapta-
tions, and their modifications in different animals forms a most fasci-
nating field in itself, and besides this it gives us an insight into the
blood relationships and degrees of kinship existing between the
multitudes of animal forms found in nature. In the study of com-
parative anatomy we are constantly surprised to find that structures
in different animals which at first sight appear to be entirely differ-
ent are really the same organs which have been simply changed in
a superficial way to serve some new purpose. For example, the
front wing of a bee and the hard shell-like wing cover of a beetle are
fundamentally the same thing, both being front wings—that of the
beetle being hardened to serve as a protection to the hind wing.
Again, the ovipositor of a katydid and the sting of a bee are identical
in their fundamental structure, differing in details simply because
they are used for different purposes. Hence, in the study of anat-
omy we must always be alert to discover what any special part cor-
responds with in related species. In order to do this, however, it
is often necessary to know the development of an organ in the
embryo or in the young after birth or after hatching, for many
complex parts in the adult have very simple beginnings in an imma-
ture stage.

Thus it becomes evident that the structural study of even one
organism soon involves us in the subjects of anatomy, physiology,
and embryology, and, if we add to this a study of its senses, its
behavior, and its place in nature, the field enlarges without limit.
The student of the honey bee realizes that a lifetime might be spent
in exploiting this one small insect.

The differences between animals are much greater on the outside
than on the inside. In the descriptions of the organs of the honey bee
anyone will know what is meant by the “alimentary canal,” the
“nervous system,” or the ‘respiratory system,” but the external
parts are so different from those of animals with which we are more
familiarly acquainted that no general reader could be expected to
know what is meant by the names applied. Moreover, the bee and its
allies are so modified externally in many ways that, at first sight,
their parts look very different even from those of other insects.
Hence, we shall give a preliminary account of the external structure
of insects in general, for it is hoped that the reader will then more
easily understand the special structure of the honey bee, and that the
application of the terms used will appear more reasonable to him.

Since all animals originate in an egg, the change into the adult
involves two different processes: One .is growth, which implies
merely an increase in size, the addition of material to material; the
other is development, which means change in shape and the produc-
12 THE ANATOMY OF THE HONEY BEE.

tion of a form with complex organs from the simple protoplasmic
mass of the egg. The part of development that takes place in the
eggshell is known as embryonic development; that which takes place
subsequent to hatching is known as postembryonic development. In
insects there are often two stages in the postembryonic development,
an active one called the larval stage and an inactive one called the
pupal stage. During the first of these the young insect is termed a
larva; during the second, a pupa. When there is no resting stage the
immature creature is often ‘called a nymph. The final and fully de-
veloped form is an adult, or imago.

Since this paper is to deal only with the anatomy of the adult, the
attractive fields of embryonic and postembryonic development must
be passed over, except for a few statements on
fundamental embryonic structure, a knowledge
of which is necessary to a proper understanding
of the adult anatomy.

When the embryo, in its course of development,
first takes on a form suggestive of the definitive
insect, it consists of a series of segments called
metameres, or somites, and shows no differentia-
tion into head, thoracic, and abdominal regions.
Typically, each segment but the first is provided
with a pair of latero-ventral appendages, hav-
ing the form of small rounded protuberances.
These appendages are of different sizes and take
on different shapes in different parts of the
body, for some of them are destined to form the
antennze, some the mouth parts, others the legs

and perhaps the cerci, while the rest of them
wre netalinct inet om remain very small and finally disappear. What
bryo, showing the see- we know of the embryology of insects is based

mentation of the head, :
thoracic, and abdom. ON the observations of a number of men who

 

inal egions, and the have worked mostly on the development of dif-
gmental appendages. i a c
ferent species. Their observations are not all
alike, but this is probably due in large part to the fact that the
embryos of different insects are not all alike. Embryos have a very
provoking habit of skipping over or omitting little and yet im-
portant things in their development, but fortunately they do not
all omit the same things. Therefore, by putting together all the
reliable information we possess, we can make up an ideal embryo
which would be typical of all insects. Such a generalized embryo is
represented diagrammatically by figure 2.
The first six or seven metameres very early begin to unite with
one another and continue to fuse until their borders are lost. These
consolidated embryonic segments form the head of the adult insect.
GENERAL EXTERNAL STRUCTURE OF INSECTS. 13

Observers differ concerning the fate of the seventh segment, but it
is most probable that a part of it fuses with the sixth segment, thus
taking part in the formation of the head, and that a part of it forms
the neck or some of the neck plates of the adult.

The appendages of these first seven segments form the antenn
and mouth parts, except one or two pairs that disappear early in
embryonic life. It is not certain that the first segment ever possesses
‘appendages, but from it arise the large compound eyes and appar-
ently also the upper lip, or labrum (Zm). The appendages of the
second segment form the feelers, or antenne (/Ant) of the adult,
those of the third (?Anz¢) disappear in insects, but they correspond
with the second antennse of shrimps and lobsters. The appendages
of the fourth segment form the mandibles (M/d). Those of the
fifth segment (Slin), when present, fuse with a median tonguelike
lobe (Zin) of the following segment, and the three constitute the
hypopharynx, or lingua of the adult. The next pair (dfx) form the
maxille, while the last (2M), or those of ‘the seventh segment,
coalesce with each other and constitute the adult labium, or lower lip.

The bodies of the head metameres fuse so completely that it is
impossible to say positively what parts of the adult head are formed
from each. The last, as already stated, possibly takes part in the
formation of both the head and the neck. Some embryologists at-
tribute the plates which usually occur in this region to the last em-
bryonic head segment, while others believe they come from the next
segment following. Sometimes these plates are so well developed
that they appear to constitute a separate segment in the adult, and
this has been called the microthorax. If this name, however, is
given to the embryonic segment from which these plates are said to
be derived, it must be remembered that it is not “thoracic” at all
and belongs partly to the head. The name cervicum has been ap-
plied to the neck region with greater appropriateness since it does
not imply any doubtful affiliation with adjoining regions. What
we really need, however, is not so much a name as more information
concerning the development of the rear part of the head and the
neck plates in different insects.

The next three segments remain distinct throughout life in nearly
all insects, but, since they bear the legs and the wings, they become
highly specialized and together constitute the thoraw. The indi-
vidual segments are designated the prothorax, the mesothoraz, and
the metathorax. The legs are formed from the embryonic ap-
pendages (fig. 2, 1Z, 2Z, 3L) of these segments, but the wings are
secondary outgrowths from the mesothorax and metathorax and
are, hence, not appendages in the strict embryological sense.

The remaining segments, nearly always 10 in number, constitute
the abdomen. The appendages of these segments, except possibly
14 THE ANATOMY OF THE HONEY BEE.

those of the tenth, disappear early in embryonic life in all insects,
except some of the very lowest species, in which they are said to form
certain small appendages of the abdominal segments in the adults.

An adult insect is often described as being “ divided” into a head, a
thorax, and an abdomen, but this is not true in most cases. -While all
insects consist of these parts, the divisions of the body are usually
not coincident with them. The prothorax in the adult is separated
from the head by the neck and is very commonly separated from the
mesothorax by a flexible membranous area. On the other hand, the
mesothorax and metathorax are almost always much more solidly at-
tached to each other, while, in most insects, the metathorax is solidly
and widely joined to the first abdominal segment, though in the flies
these latter two segments are usually separated by a constriction. In
such insects as ants, wasps, and bees a slender, necklike peduncle
occurs between the first and second segments of the abdomen, the
first being fused into the metathorax so that it appears to be a part
of the thorax. This is the most distinctive character of the order
Hymenoptera, to which these insects belong.

The body wall of insects is hard on account of the thick layer of
chitin which exists on the outer side of the true skin. Chitin is a sub-
stance similar to horn, being brittle, though tough and elastic. It
gives form and rigidity #o the body and affords a solid attachment for
the muscles within, since insects have no internal framework of bones
such as vertebrate animals have. The skin between the segments is
soft and unchitinized and thus forms a flexible intersegmental mem-
brane which is often very ample and, in the abdomen, allows each seg-
ment to telescope into the one in front of it.

The chitin of each segment is not continuous, but is divided into
plates called sclerites. The most important of these are a tergum.
above and a sternum below, but, in the case of the thorax, these two
plates are separated on each side by another called the plewrum, which
lies between the base of the wing and the base of the leg. Pleural
plates are sometimes present also on the abdominal segments. These
principal segmental plates are usually separated by membranous
lines or spaces, which permit of more or less motion between them.
Such lines are called sutures in entomology, though strictly this term
should be applied only to the lines of fusion between adjoining parts.

The terga, pleura, and sterna of each segment are furthermore
subdivided into smaller sclerites, which may be termed tergztes, pleu-
rites, and sternites, respectively. The sutures between them are
sometimes membranous also, but most frequently have the form of.
impressed lines or narrow grooves. In such cases they are generally
nothing more than the external marks of ridges developed on the
inside of the body wall to strengthen the parts or to give attachment
to muscles, Since these sutures are conspicuous marks on the outside
GENERAL EXTERNAL STRUCTURE OF INSECTS. 15

of an insect, they are usually regarded as morphologically impor-
tant things in themselves, representing a tendency of the tergum, pleu-
rum, or sternum to separate into smaller plates for some reason. The
truth about them would appear to be just the opposite in most cases—
they are the unavoidable external marks of an internal thickening
and strengthening of the plates. In a few cases they may be the
confluent edges of separate centers of chitinization. Hence, most of
the sutural lines in insects appear to signify a bracing or solidifying
of the body wall rather than a division of it.

Since the body wall of insects is continuous over all the surface it
contains no articulations of the sort that occur between the bones in
the skeleton of a vertebrate. Although insects and their allies be-
long to the class of animals known as the Articulata, yet an articu-
late articulation is simply a flexibility—two chitinous parts of the
exoskeleton are movable upon each other simply by the intervention
of a nonchitinized, flexible, membranous part. While there are often
special ball-and-socket joints developed, these are always produced
on the outside of the membranous hinge and simply control or limit
the movement of the articulation.

The head of an adult insect is a thin-walled capsule containing the
brain, the ventral head ganglion of the nervous system, the pharynx
and anterior part of the csophagus, the tracheal tubes, and the
muscles that move the antenne and the mouth parts. Its shape varies
a great deal in different insects, being oval, globular, elongate, or
triangular. In some it is flattened dorso-ventrally so that.the face is
directed upward and the mouth forward, but in most, including
the bee, it is flattened antero-posteriorly so that the face looks for-
ward and the mouth is directed ventrally. In a few it is turned so
that the face is ventral. The walls of the head are usually divided
by sutures into a number of sclerites, which in general are located
and named as follows: The movable transverse flap forming the
upper lip is the labrum. Above it is a sclerite called the clypeus,
which is a part of the solid wall of the head and carries the anterior
articulations of the mandibles. The clypeus is sometimes divided
transversely into an anteclypeus (“clypeus anterior,” “epistoma”)
and into a post-clypeus (“clypeus posterior”). Above the clypeus
is the front, a plate usually occupying the upper half of the face
between the compound eyes and carrving the antenne. The top of
the head is called the vertex, but does not constitute a separate scle-
rite. The sides of the head below the compound eyes are often sepa-
rated by sutures from the anterior and posterior surfaces and are
known as the genw. The back of the head is formed by the occiput,
which surrounds the large opening or foramen magnum that leads
from the cavity of the head into that of the neck. The parts pos-
terior to the gene, carrying the posterior mandibular articulations,
16 THE ANATOMY OF THE HONEY BEE.

are sometimes separated from both the occiput and the gene and are
known as the postgene. In a few insects, especially beetles, one or
two median plates occur in the ventral wall of the head posterior to
the base of the labium. These are the gular sclerites. Finally, small
plates are sometimes found about the bases of the antenne and be-
tween the bases of the mandibles and the genx. The latter have
been termed the trochantins of the mandibles. The term epicranium
is often used to include all the immovable parts of the head, but is
frequently applied only to the dorsal parts. Most of these sclerites
preserve a pretty definite arrangement in the different orders, and
they are probably homologous throughout the entire insect series,
though they are in some cases very much distorted by special modi-
fications and are often in part or wholly obliterated by the disap-
pearance of the sutures. Embryologists are coming to the conclu-
sion that the sclerites of the head have no relation to the primitive
segments. The latter very early consolidate into a head with a con-
tinuous wall, while the sutures defining the sclerites are formed
later. Some of the older entomologists were led, from a study of
the sclerites, to suppose that the head consisted of a number of seg-
ments, but it has been shown that these anatomical segments do not
correspond with the embryonic ones.

The appendages growing from the front of the face are the
antenne (fig. 9A, Ant) or “ feelers” and consist of a series of joints
or segments.

At the lower edge of the face is the front lip or labrum (fig. 9A,
Lm), behind which are the median epipharyna, the paired mandibles
(Md) and maville, the median hypopharynz, and the labium or under
lip. All these organs together constitute what are known as the
mouth parts or trophi. They vary greatly in shape and appearance
in different insects according to the nature of the food, but their
typical form is usually taken to be that shown by the lower insects
which feed on solid food and have biting mouth parts. Figure 3,
representing the jaws and lips of the common black cricket, is given
as an example of generalized insect mouth parts.

The labrum (fig. 9A, Zm) is usually a simple transverse flap in front
of the mouth, being developed, as already shown, from a similarly
situated lobe on the first segment of the embryo (fig. 2, Zm).

The epipharynx (fig. 19, Hphy) is a sort of dorsal tongue, and is
situated on the membrane leading into the mouth from behind the
labrum.

The mandibles (figs. 3A; 9A, Md) are typically formed for
biting, being heavy organs situated immediately behind the labrum
and working sidewise on a hinge articulation with the head. Their
cutting edges are usually notched and toothed, though smooth in the
worker bee.
GENERAL EXTERNAL STRUCTURE OF INSECTS. 17

The maxille (fig. 3 B and B) are complicated appendages in their
typical form. Each consists of a principal piece called the stipes (St),
which is hinged to the head by means of a smaller basal piece, the
cardo (Cd). Terminally the stipes bears an outer lobe, the galea
(Ga), and an inner lobe, the Jacinia (Lc). On the outer side, at the
base of the galea, it carries a jointed appendage called the mawillary
palpus (Pip).

The hypopharynx (fig. 3 C’and D, HpAy) is a median, ventral,
tonguelike organ, called also the ingua, situated either on the upper
surface of the labium or on the membrane between this organ and the
mouth. It is de-
veloped principally
from a median lobe
of the head of the
embryo behind the
mouth (fig. 2, Zin),
but some entomol-
ogists claim that it
is compounded of
this lobe and two
smaller lateral ones
developed from the
appendages of the
fifth embryonic
head segment (fig.
2, Slin), the super-
lingue.

The labium (fig.
3 C and D) consti-
tutes the under lip

 

J Fie. 3.—Example of generalized insect mouth parts, from
of the adult, but it common black cricket (Gryllus pennsylvanicus) : A, man-

dibles; B, B, maxillew, ventral view; C, labium or second

1s formed from the maxille, ventral view; D, labium, lateral view.

two appendages of

the seventh segment in the embryo, which fuse with each other. For
this reason it is often called the second mamwillw. It consists of a basal
submentum (Smt) bearing the mentum (J/t), which in turn carries
three parts, a median ligula (Zg) and two lateral palpigers (Pig).
The latter support the /abial palpi (Plp), while the ligula bears four
terminal lobes, of which the median ones are called the glosse (Gls)
and the lateral ones the paraglosse (Pgl). If we should cut the
labium into two parts along its midline we should see that even in
the adult stage each half is very similar to one maxilla. The only
discrepancy to be noticed in the example given (fig. 3) is that, there

22181—No. 1S—10-—2
18 THE ANATOMY OF THE HONEY BEE.

is no maxillary palpiger, but many insects possess a corresponding
part in the maxilla, frequently distinguished as the palpéfer.

The neck or cervicum is usually a short membranous cylinder which
allows the head great freedom of motion upon the thorax. In nearly
all insects its lateral walls contain several small plates, the cervical
sclerites, while, in many of the lower species, dorsal, ventral, and
lateral sclerites are present and highly developed. As already stated,
the origin of these plates is doubtful. Some entomologists would
derive them from the prothorax, others think they come from the
last head segment, while still others think that they represent a
separate segment. Only pure anatomists, however, entertain this
last view and call this supposed segment the “ microthorax,” for
embryologists have not yet reported a metamere between the labial
segment and the prothoracic segment. Most embryologists who have
studied the subject admit that some of the cervical sclerites may be
formed from the last embryonic head somite which carries the labium
and probably forms a part of the back of the head. Therefore, if
it is desirable to retain the word microthorax as a name for a true
segment, it can be applied only to this labial metamere.*

The thorax, as has already been stated, is a distinct anatomical
region of the body rather than a “ division” of the body, since it car-
ries both the legs and the wings and contains the large muscles for
each. Since the prothorax does not possess wings, it is not so highly
developed otherwise as the two wing-bearing segments, and is, indeed,
generally reduced in some ways, some of its parts being frequently
rudimentary. Therefore we shall base the following description of
a typical segment on the structure of the wing-bearing segments.

A typical thoracic segment, then, presents four surfaces, as does also
the entire body. These are a dorsum above, a venter below, anda
latus® on each side. From these names we have the terms “ dorsal,”

 

@Jn a former paper on the thorax of insects (Proc. U. 8S. Nat. Mus., XXXVI,
1909, pp. 511-595) the writer probably drew a too definite conclusion on the
subject of the “ microthorax.” The origin of the neck sclerites has probably
never yet been actually observed. Comstock and Kochi (Amer. Nat., XXXVI,
1902, pp. 18-45), in summarizing the segmentation of the head, accredited
the gular and cervical sclerites to the labial segment, but did not_recognize the
latter as taking part in the formation of the true head capsule. Riley, how-
ever, in his study of the development of the head of a cockroach (Amer. Nat.,
XXXVIII, 1904, pp. 777-810), states that in Blatta the labial segment does
form a part of the back of the head and that the posterior arms of the
tentorium are derived from it. Borner (Zool. Anz., XXVI, 1908, pp. 290-315)
and Crampton (Proc. Acad. Nat. Sci. Phila., 1909, pp. 3-54) believe that the
cervical sclerites are_derived principally from the prothoracic segment. The
notion that they constitute a separate segment, the “ microthorax,” equivalent
to the maxilliped segment of the centipedes, has been elaborated principally
by Verhoeff in his numerous writings on the Chilopoda and Dermaptera.

>The writer introduces this word here because he knows of no other term
applied to the side of the segment in this sense,
GENERAL EXTERNAL STRUCTURE OF INSECTS. 19

“ventral,” and “lateral.” The chitinous parts of the dorsum con-
stitute the ¢ergum, of the venter, the sternum; and of the latus, the
pleurum.

The tergum of the wing-bearing segments usually consists of
two plates—a front one or true notum (fig. 4, VY) carrying
the wings, and a posterior one, which the writer has termed the
postnotum or pseudonotum (PN), having no connection with the
wings. The first is often more or less distinctly marked into three
transverse parts called the prescutum (Psc), scutum (Sct), and scu-
tellum (Scl). In such cases the exposed part of the postnotum is
called the postscutellum (Pscl). From either the anterior or the pos-
terior margin of the tergum, or from
both, a thin transverse plate projects
downward into the interior of the
thorax for the attachment of muscles.
These plates are the phragmas (Aph
and Pph). The notum supports the
wing on each side by two small lobes,
the anterior and posterior notal wing
processes (ANP and PNP). Behind
the latter is the attachment of the
axillary cord (AxC) or basal ligament
of the wing. A large V-shaped ridge
on the under surface of the notum hav-
ing its apex forward is the “ entodor-
sum.” (A better name would be
entotergum.)

The pleurum consists principally of
two plates, the episternum (fig. 4, E'ps) Fic. 4.—Diagram of generalized
and the epimerum (Epm)' lying before thoracic segment, left side.
and behind a vertical groove, the pleural suture (PS), which extends
from the pleural cowal process (CxzP) below to the pleural wing
process (WP) above. The pleural suture marks the position of a
heavy internal ridge, the pleural ridge or entopleurum. The epi-
merum is connected with the postnotum (PV) behind the base of the
wing. These parts occur in almost all insects. In some of the lower
ones another plate is present in front of the episternum which may
be called the preepisternum (Peps).* Lying along the upper edge of

 

 

*Objection may be made to the use of the term “ preepisternum” on the
ground that it combines a Latin prefix with a word compounded of Greek ele-
ments. The same may be urged against “ prephragma,” “ postphragma,” “ pre-
paraptera,” and “ postparaptera,” words introduced by the present writer in a
former paper on the thorax (Proc. U. 8. Nat. Mus., XXXVI, 1909, pp. 511-595).
However, we are barred from making up equivalent terms with the Greek pre-
fixes pro and meta because these are used to designate the first and the third
20 THE ANATOMY OF THE HONEY BEE.

the pleurum and associated with the under surface of the wing base
are several small plates known as the paraptera (P).* Two lie above
the episternum in front of the pleural wing process and are the
episternal paraptera or preparaptera (1P and 2P), while one or
occasionally two are similarly situated behind the wing processes
and are the epimeral paraptera or postparaptera (3P and 4P). The
preparaptera afford insertion for the muscle concerned in the exten-
sion and pronation of the wing.

The cova (Cx), or basal segment of the leg, is hinged to the seg-
ment by a dorsal articulation with the pleural coxal process (CwP),
and by a ventral articulation (7nC’) with a plate called the trochan-
tin (Tn) lying in front of it and connected above with the lower
end of the episternum (ps). Hence, while the leg is of course con-
tinuous all around its base, by means of membrane, with the body-
wall, its movement is limited to a hinge motion by these two special
articulations of the chitin.

The sternum or ventral plate of the segment is not so complicated as
are the tergum and pleurum. It is often divided transversely into
three parts, however, and some authors say typically into four. These
parts have been named the presternum (Ps), sternum proper (8),

 

segments of the thorax or their respective parts. Entomologists have already
established the system of referring a part to the front or back of any individual
segment by the Latin prefixes pre (or pre) and post as used in “ prescutum,”
“ presternum,” “ postscutellum,” and “ poststernellum.” Furthermore, pre and
post are so indiscriminately used in English combined with Latin, Greek, and
even Anglo-Saxon words that they may be regarded as general property.
Hence, in order not to sacrifice an anatomical system, which certainly needs
to be fostered in every way, the writer has preferred to sacrifice strict gram-
matical rules by applying pre and post, regardless of the origin of the noun
in the case, to designate anterior and posterior parts of the same segment. We
already use such hybrid terms as “ presternum,” ‘‘ mesotergum,” and “ meta-
tergum.”

.The name “ preepisternum” has been applied by Hopkins (Bul. 17, Pt. I,
technical series, Bur. Ent., U. S. Dept. Agr., 1909) to a part of the mesepister-
num of Dendroctonus—a plate apparently not homologous with the preepisternal
element of the thorax in primitive insects.

@The name “parapterum” is taken from Audouin’s term paraptére (Ann.
des Sci. Nat., I, 1824, pp. 97-185, 416-432), and its application, as used by the
present writer, is based on Audouin’s definition given in his Chapter III,
“ Considerationes generales sur le Thoraw,” where he says (p. 122): “ Finally
there exists a piece but little developed and seldom observed, connected with
both the episternum and the wing. It is always supported by the episternum
and is sometimes prolonged ventrally along its anterior margin, or again,
becoming free, passes in front of the wing and may even come to lie above
the base of the latter. At first we designated this sclerite by the name of
Hypoptére but on account of its change of position relative to the wing base
we now prefer the name of ParaprTErE.” ‘The first part of his description leaves
no doubt that Audouin referred to the little pleural plate beneath the front
of the wing which is usually very inconspicuous except in carefully dissected
GENERAL EXTERNAL STRUCTURE OF INSECTS. 21

sternellum (Sl), and poststernellum (Pst). In some of the lower
insects a plate (#) occurs at each side of the presternum or of the
sternum which seems to fall in line with the preepisternum of the
pleurum. This has been variously called a part of the presternum,
the coxosternum, an accessory sternal plate, and the sternal laterale.
The inner surface of the
sternum carries a large
two-pronged process
called the furca or ento-
sternum.

This plan of structure
for the mesothorax and
the metathorax prevails
throughout all insects.
The honey bee probably
presents the greatest de-
parture from it, but even
here the modification consists principally of a suppression of the
sutures of the pleurum resulting from a condensation of the parts.

The leg (fig. 5) of an adult insect consists of a number of joints
or segments. It is attached to the body, as just described, by a thick

 

Fig. 5.—Typical insect leg.

 

specimens. In such preparations, however, one finds that there are in most
eases two sclerites here instead of one, and, furthermore, that one or ocza-
sionally two others are similarly situated beneath the rear part of the wing
base behind the pleural wing process. The present writer has, therefore,
made the term “ paraptera” cover this whole row of little plates, distinguish-
ing those before and those behind the pleural wing process by the designations
given above.

In the latter part of Audouin’s definition it would seem that he may have
confused the rudimentary tegula as it exists in some insects with the parapte-
rum, but even this is not probable since he says it is always connected with
the episternum, which is never true of the tegula. In his description of the
thorax of beetles, Dytiscus, Carabus, Buprestis, and Curculio, it is evident
that he regards the anterior upper part of the episternum as the parapterum
fused with the latter plate. In fact, in each case he definitely states that such
is the case and, in describing Dytiscus circumflerus, he says (p. 420): ‘“ The
episternum, the parapterum, and the epimerum all fuse dorsally and constitute
a support for the wings and tergum.” While Audouin is undoubtedly mis-
taken in this homology, especially in the mesothorax, he at least shows that
his “ paraptére” is a part of the pleurum. Hence modern writers such as
Packard and Folsom who make the term “paraptera”’ synonymous with
“tegule” are certainly wrong. The tegula is a dorsal scale or its rudiment
at the humeral angle of the wing, while the parapterum is a co-existent scle-
rite below this part of the wing base. The present writer agrees with Comstock
and Kellogg, who, in their Elements of Insect Anatomy (first edition), define
the little sclerite in front of the base of the wing in the locust, articulated to
the dorsal extremity of the episternum, as the “ parapteron,” though in this
insect there are here really two of these parapteral plates instead of one.
22 THE ANATOMY OF THE, HONEY BEE.

basal joint called the cova (Cx). Beyond this is a smaller joint
called the trochanter (Tr), this is followed by a long and strong
segment, the femur (/), which extends outward from the body, while
bending downward from its distal end is the long and slender tibia
(7b), followed finally by the foot, or tarsus (Tar). The tarsus itself
consists typically of five small segments of which the last bears a pair
of claws (Cla). The under surfaces of the tarsal joints are often
provided with small cushions or pads called pulilli. Those between
the claws are generally specially prominent and are called the
empodia (Emp). The leg varies greatly in shape in different in-
sects but usually preserves all of these parts. The segments of the
tarsus, however, are frequently reduced in number.

The adult wing is a thin expanse of membrane supported by hollow
branching rods called reins. It originates as a hollow outgrowth of
the body-wall, but soon becomes flattened out dorso-ventrally and the

 

   

   

Cu

 

4
1 ‘ x i
5A US Cu,

Fic. 6.—Diagram of generalized insect wing and its articulation to first plate (N) of
the tergum.,

contained trachew or air tubes mark out the courses of the veins.
These veins form various patterns in different insects, but they can all
be derived by modification from one fundamental plan. This plan is
shown diagrammatically by figure 6. The first vein, which usually
forms the anterior margin of the adult wing, is the costa ((). The
next vein is the subcosta (Sc), which in typical cases divides into
two branches (Sc, and Se,). The third and usually the principal
vein is the radius (R). It divides dichotomously into five branches
(R, to &,), the anterior brarich of the first fork remaining single.
The next vein is the media (Af), which forms four branches (J/, to
M,). The fifth is the cubitus (Cw), which again is two-branched.
The remaining veins are called the ana?s and are designated indi-
vidually as the first anal (1A), second anal (2A), ete.

Several cross-reins of common recurrence should be noted. The
first is situated near the base of the wing between the costal and
subcostal veins and is known as the hwmeral cross-vein. A second
GENERAL EXTERNAL STRUCTURE OF INSECTS. 98

occurs between the radius and the media near the center of the wing
and is called the radio-medial cross-vein. Another one, the medio-
cubital, is similarly located between the media and the cubitus,
while a fourth, called the median, occurs between the second and
third branches of the media. The areas of the wing surface inclosed
by the veins, the cross-veins, and the margins of the wing are known
as the cells.

A great many different names are applied by different entomolo-
gists to the veins of the wings, both of the same and of different
insects. The nomenclature here given is the one first consistently
applied by Comstock and Needham and now used by a large number
of entomologists working in different orders of insects.

The wing is articulated at its base (except in mayflies and dragon-
flies) to the anterior and posterior wing processes of the notum
(fig. 6, ANP and PNP) and to the wing process of the pleurum (fig.
4, WP) by several small articular sclerites called avillaries. Two
of these, the first (1Aa) and the fourth (4.17), form a hinge with the
anterior and the posterior notal wing processes, respectively, while
the second (2d) articulates below with the wing process of the
pleurum, constituting thus a sort of pivotal element. The third awit-
lary (Ax) intermediates between the bases of the anal veins and the
fourth axillary—except when the latter is absent (as it is in nearly
all insects except Orthoptera and Hymenoptera), in which case it
articulates directly with the posterior notal process. The thin mem-
brane of the wing base may be called the awillary membrane (lad).
On its anterior edge is a hairy pad, the tegula (Tq), which is some-
times a large scale overlapping the humeral angle of the wing. The
posterior margin of the axillary membrane is thickened and may be
called the axillary cord (Aw) or basal ligament of the wing.

The base of the costa is not directly associated with any of the
axillaries, but is specially connected by tough membrane below with
the episternal paraptera. The subcosta abuts against the end of
the curved neck of the first axillary. The radius is either attached
to or touches upon the anterior end of the second. The media and
cubitus are usually associated with each other at their bases and also
more or less closely with one or two median plates (m) in the wing
base. These plates, however, are not of constant shape and occur-
rence as are the articulating axillaries. The anals are generally
attached to the outer end of the third axillary, which acts as a lever
in the folding of the wing.

A few insects have a generalized wing almost identical with the
diagram (fig. 6), but most of them depart from it in varying degr ees,
Few go so far, however, as the honey bee, whose venation is very
different, but yet the funduimental basal structure is the same even
24 THE ANATOMY OF THE HONEY BEE.

here, as will be shown in the special description of the wing of the
bee.

The abdomen consists almost always of 10 segments. There are
never any more than this number well developed in adult insects, and
if there are fewer the reduction is due to a modification of the ter-
minal segments to accommodate the external organs of reproduction.
The posterior opening of the alimentary canal is at the end of the
tenth segment, which carries also two small appendages at the sides of
theanus. These are called the cerc? (fig. 8, Cer). In some insects they
are short, styletlike processes, in others they are long and many
jointed, while in many they are absent. The cerci are supposed to
be developed from the embryonic appendages of the tenth segment,
although, on the other segments, these appendages disappear before
the embryo hatches, except in some members of the lowest wingless
order of insects, which have a pair of cercuslike appendages on each
segment of the abdomen.

Each abdominal segment presents a tergum above and a sternum
below; the former usually also reaches far down on the sides and
overlaps the edges of the sternum. In some insects one or more small
pleural plates intervene between the tergum and the sternum, but
the abdominal pleura are never developed in any way suggestive of
a thoracic pleurum. Very frequently there is present an upper
pleural plate, or epipleurite, adjoining the edge of the tergum and a
lower, or hypopleurite, adjoining the edge of the sternum. The line
separating these two sclerites, however, is horizontal and can not
correspond with the vertical suture of a thoracic pleurum between the
episternum and the epimerum extending from the base of the leg
to the base of the wing.

The most complicated structures on the abdomen are the external
organs of reproduction. In the male these serve as clasping organs
and take on a great variety of forms in different species. The organs
in the female form an ovipositor and are of much more definite and
constant structure.

The ovipositor (fig. 8), in its most perfect development, consists of
three pairs of long, closely appressed bladelike processes called
gonapophyses (1G, 2G, 3G). These six pieces fit neatly together and
form an organ by means of which the female makes a hole in the
ground or in the bark of a tree, or punctures some other insect, and
then places her eggs in the cavity thus produced. An interesting fact
in this connection is that the sting of a wasp or bee is simply a modi-
fied ovipositor. This can be proved by a comparison of the organs
themselves or by a study of their development. Each is formed from
six little peglike processes that grow out from the sterna of the eighth
and ninth abdominal segments of the larva or young soon after hatch-
GENERAL EXTERNAL STRUCTURE OF INSECTS. 25

ing (fig. 7, 1G, 2G, and 3@). At first there is only one pair of these
processes on each of the two segments, but those on the ninth soon
split each into two, thus producing two pairs on this segment. The
opening of the oviduct (OvO) is on the
eighth segment between the bases of the
first gonapophyses.

The ovipositor of the longhorned grass-
hopper, shown by figure 8, may be taken as
a typical example of this organ. The
median pair of gonapophyses on the ninth
segment (2G) remain slender and fuse at yy ae
their bases into a small bulblike swelling
open below (SAB). The pair from the X oC
eighth segment (1G) form two long blade- fo
like pieces, which fit by sliding articula- An 2G
tions upon the lower edges of the corre- soe pide ae
sponding second gonapophyses (2G). The male insect and early stage in
first can therefore be worked back and ne ee ae
forth while they are braced and held in — which is formed the ovi-
position by the second pair. The third prety of mo on and asain
gonapophyses (3G), or the outer pair of
the ninth segment (the left one in figure 8 is shown as if cut off near
its base), form two long flat blades which are closely appressed
against the outer surfaces of the others. In the detailed study of
the bee it will be shown how closely the structure of the sting corre-
sponds in every way with that of this ovipositor.

  

   

hy | !
Sp 3G
Fig. 8.—Example of a swordlike ovipositor, from a longhorned grasshopper (Cono-

cephalus sp.), illustrating the fundamental similarity of structure with the sting of the
bee, fig. 36.

Some entomologists have supposed that the original two pairs of
gonapophyses represent the embryonic appendages of the eighth and
ninth segments, and they would thus establish a homology between
the ovipositor or sting and the legs and mouth parts. It has been
shown, however, that the true appendages of the abdominal segments
disappear in embryonic life while the gonapophyses appear much
later, during early nymphal or larval life. Furthermore, each pair
¥6 THE ANATOMY OF THE HONEY BEE.

of gonapophyses arises in a median depression on the ventral side of
the segment while the true appendages are latero-ventral. Hence,
the evidence is very much against this theory and the gonapophyses
appear to be special secondary processes of the body, wall.

All insects do not have ovipositors of the sort described above.
Flies, beetles, moths, and butterflies do not. Such insects simply
drop their eggs from the orifice of the oviduct or deposit them in
masses upon the external surfaces of'various objects. In some of
the flies, however, the terminal segments are long and tubular and
entirely telescoped into one another. They are hence capable of
being protruded in the form of a long tapering tube-having the open-
ing of the oviduct near the tip. This enables the insect to deposit its
eggs in deep crevices, but the structure is not a true ovipositor—it is
simply the abdomen itself stretched out.

Insects breathe through a series of small holes situated along each
side of the body. These breathing apertures are called spiracles and
they lead into a system of internal air tubes called trachew. There
are nearly always 10 spiracles present on each side of the body. Two
are located on the thorax, the first between the prothorax and the
mesothorax, the second between the mesothorax and the metathorax,
while the other eight are situated on the first eight abdominal seg-
ments. Some embryologists believe that the spiracles of the pro-
thorax move forward in early embryonic life and unite with each
other in front of the hypopharynx to form the salivary opening, their
trachee constituting the salivary ducts.

After this review of the general external structure of insects we
may proceed to a more detailed account of the parts and organs of
the honey bee.

III. THE HEAD OF THE BEE AND ITS APPENDAGES.

The head of an insect, as already explained, is a composite organ
formed of six or seven primitive segments, each of which, except the
first, typically bears a pair of appendages (fig. 2). The antenne are
developed from the embryonic appendages of the second segment,
the mandibles from the fourth, the maxille from the sixth, and the
second maxille, or labium, from the seventh. The appendages of
the third segment disappear in early embryonic life while those of
the fifth segment, when the latter is present, fuse with a median
tonguelike lobe of the next segment to form the hypopharynx of
the adult.

1. THE STRUCTURE OF THE HEAD.

The general appearance and outline of the head of a worker bee
are shown from before and behind by figure 9, A and B. In facial
view the head is triangular, with the apex below. The side angles
THE HEAD OF THE BEE AND ITS APPENDAGES. 27

are rounded and capped by the large compound eyes (#). In the
opposite direction the head is very much flattened, the greatest diame-
ter being crosswise through the middle of the eyes. The face is con-
vex, while the. posterior surface is somewhat hollowed out and fits
snugly upon the anterior end of the thorax.

The large lateral eyes (fig. 9 A, Z’) are called the compound eyes,
because each is composed of a large number of separate eye elements
forming the little hexagonal facets visible on the surface. All of
these facets together constitute the cornea, or the transparent outer
surface of the eye, which in the bee is densely clothed with long hairs.
The dark color of the eye is located in the deeper parts, but these will
be described in the section dealing with the nervous system. On the

 

Fic. 9.—A, front view of head of worker bee with mouth parts (Prb) cut off a short
distance from their bases; B, corresponding view of posterior surface of head.

top of the head between the compound eyes are the three simple eyes,
or ocelli (O), arranged in a triangle with the median ocellus in front.

Between the lower halves of the large eyes and near the center of the
face arise the antenne (Ant), each of which is inserted into a small,
circular, membranous socket of the head wall, and consists of a long,
basal, 1-segmented stalk carrying a terminal 11-jointed arm movably
articulated to the stalk and generally hanging downward from it.
(In the drone the terminal arm consists of 12 joints.)

The mouth parts are attached at the lower part of the head, and
consist of the mandibles (Md) laterally and the maville (Jz)
and labium (Lb) mesially. The latter two include the set of elongate
bladelike organs surrounding the protrusible “tongue,” which to-
gether constitute what is commonly known as the proboscis (Prb).
28 THE ANATOMY OF THE HONEY BEE.

When not in use the parts of the proboscis are bent back beneath
the head. By referring to figure 9B, giving a posterior view of the
head, it will be seen that the basal parts of both the maxille (S¢)
and the labium (J/¢) are suspended in a large hollow on the back of
the cranium. This may be called the cavity or fossa of the proboscis
(PrbFs). Between the mandibles on the front of the head (fig.
9A) is a transverse movable flap, the Jabrum (Lm), attached to the
lower edge of the front wall of the head and constituting the upper
lip. The mouth (Mth) lies behind the labrum and the mandibles
close beneath it.

Below the antennal sockets is a transverse, slightly arched suture
(a) which turns downward on each side and extends to the inner
angles of the bases of the mandibles. The area bounded by this
suture is the elypeus (Clp) and the suture itself may be called the
clypeal suture.

On the posterior surface of the head (fig. 9B) is seen the pen-
tagonal foramen magnum (For) by means of which the cavity of
the head communicates with that of the thorax and through which
pass the nerves, oesophagus, blood vessel, and tracheal tubes. A
small rod (en) inside the head arches transversely over the fora-
men magnum, cutting it into a dorsal and a ventral half. At each
side of the foramen is a large pit (c) which marks the base of an
internal chitinous beam of the head known as the mesocephalic pillar.
The opposite end of this pillar unites with the front wall of the
head on the clypeal suture below the antennz, where it produces
another smaller pit (0).

Below the foramen magnum and separated from it by a wide trans-
verse bridge of the cranial wall is seen the large fossa of the proboscis
(fig. 9B, PrbFs) having the shape of an inverted U. The side walls
of this cavity are chitinous and from their upper edges are suspended
the maxilla, while the base of the labium is contained in the mem-
. branous floor of the fossa. The base of the labium projects from the
-head beneath or behind the mouth opening and its dorsal surface
forms the floor of a preoral cavity surrounded by the bases of the
mouth parts and labrum.

Tt will be seen from the above description that the head wall of the
bee contains no suture except that bounding the clypeus and the one
which separates the labrum from the latter. Many of the higher
insects have the head wall completely continuous, showing no division
at all into sclerites, but, in such forms as a grasshopper or cockroach,
and, in fact, most of the lower insects, the head as well as the other
parts of the body is made up of a number of plates. Hence this may
be regarded as the primitive condition, and it is presumed that the
head of the bee has been produced from one whose wall was divided
by sutures into a number of distinct parts. Therefore the different
THE HEAD OF THE BEE AND ITS APPENDAGES. 29

regions of the bee’s head may be named according to the sclerites with

which they correspond in other insects.

Thus, the part of the face

above the clypeus and between the compound eyes may be called the
front (fig. 9A, Ft), the parts below the compound eyes the gene (@e),

and the top of the head the vertex
(Va). The area on the back of the
head around the foramen magnum
may likewise be termed the occipital
region (fig. 9B, Oc) and the parts be-
hind the gene and the lower halves
of the compound eyes the postgene
(Pge).

The worker, queen, and drone differ
conspicuously in the shape and size of
the head, as will be seen by comparing
A, B, and C of figure 10. In these
drawings the front has been removed
in order to show various internal
parts, which will be described later.
While the head of the worker (A) is
triangular in facial view, that of the
queen (B) is more rounded and wider

in proportion to its length. The head’

of the drone (C) is much larger than
that of the female and is nearly cir-
cular in outline. In shape the head
of the queen is intermediate between
that of the worker and that of the
drone, but in size it is somewhat
smaller than the head of the worker.
The eyes (#) of the worker and queen
are about equal, but those of the drone
are enormously enlarged and are
broadly contiguous on the vertex and
the upper part of the front. On this
account the ocelli (0) of the drone are
crowded down on the front nearer the
bases of the antenne and the front
itself is very much narrowed above.
The antenne of the drone consist of
13 segments, while those of the females

 

Fig. 10.—A, anterior view of head of
worker, with front, antennsy, and
proboscis removed ; B, correspond-
ing view of head of queen; C, same
of drone.

have but 12 segments. The mandibles are largest proportionately in
the queen and are very small in the drone. Those of the worker have
a smooth terminal edge, while this edge is notched in the queen and
the drone. The parts of the proboscis are much longer in the worker
30 THE ANATOMY OF THE HONEY BEE.

and capable of much more action than in the queen and drone, which
are almost entirely dependent upon the workers for their food.

The internal structure of the cranium may be studied best in a longi-
tudinal section of the head (fig. 11). In order to prepare a section
for this purpose imbed the head in paraffin and then carefully slice
off one side with a sharp knife or razor just outside of the bases of
the mandible and antenna. Holding the remainder in the block of
paraffin or fastening the whole in a dish of water or alcohol, care-
fully dissect away the soft parts from the head cavity so as to expose

 

Fic. 11.—A, longitudinal section through head of worker between the median plane and
outer edges of mandibles (Md) and antenne (Ant) of left side, all internal soft parts
removed; B, corresponding section through head of drone, except that the pharynx
(Phy) and cesophagus (d/) are not removed.

the internal chitinous parts shown in figure 11 A and B. These
figures, however, represent a slice of the head taken from between the
median plane and the outer edges of the antennal and mandibular
bases of the left side. Thus only the parts on one side of the mid-
line are shown. Figure A is from a worker and Figure B from a
drone. In the latter the pharynx and cesophagus are retained and
the neck is not removed. Figure 20 shows the head cut open from
above and the mouth parts removed. A specimen so cut and bviled
a short time in caustic soda or potash to remove the soft parts will
be found a valuable adjunct to this study.
THE HEAD OF THE BEE AND ITS APPENDAGES. 31

The principal parts of the internal skeleton of the head, or ento-
cranium, consist of two large,-oblique, strongly chitinous bars form-
ing a brace between the anterior and the posterior walls of the head
(fig. 11 A and B, Zen, showing the parts on the left side only, and
fig. 19, Zen). These bars have been named by Macloskie (1881) the
mesocephalic pillars. As already pointed out the base of each is
marked externally by a conspicuous pit (fig. 9 B, c) laterad of the
foramen magnum, and its facial end by a smaller pit (fig. 9 A, 0)
in the clypeal suture near the upper end of each side of the latter.
The bases of these pillars are connected by the slender bar (fig. 11 A,
ten), already noticed, arching over the foramen magnum (fig. 9 B,
ten). This bar and the two pillars represent what is called in other
insects the ¢entorium. In the embryo the tentorium is formed from
tubular ingrowths of the head wall which unite internally and
assume different shapes in different insects. Since the air tubes of
the body also first appear as tubular ingrowths of the body wall,
some entomologists have supposed that the hollow tentorial in-
growths of the head represent the spiracular tubes of the head
which are, otherwise, lacking. However, there is not sufficient evi-
dence to support such a view as this, and there is no reason why the
tentorium should not have been originally designed simply to give
greater rigidity to the walls of the head where the latter support the
appendages.

The usual form of the tentorium in the lower insects is that of an
X, with a large central body, situated like a brace across the lower
part of the head, having two of the arms directed anteriorly and
laterally and two directed posteriorly and laterally, and while the
former are said to be ingrowths from the mandibular segment, there
is some difference of opinion concerning the segment to which the
latter belong. Riley states that they are formed in the labial seg-
ment of the cockroach and Carriere and Burger describe the same
thing for the mason bee. Other authors have ascribed them to the
maxillary segment, but they may, in later stages, lie in this segment
and thus appear to belong to it, while they originated in the one
following, having moved forward on account of the condensation
of the back part of the head. The tentorium of the honey bee,
consisting as it does of the two great mesocephalic pillars (fig. 11
A and B, Zen) and the small arched bar (¢en) is so highly modified
that it is hard to see just how its parts are to be homologized with
the parts of an X-shaped tentorium. Probably the two pillars repre-
sent the separated halves of the X, while the slender arch is an addi-

tional structure. In any case we have not enough evidence to war-
"rant us in regarding the tentorial invaginations as modified trachee,
or their external pits as rudimentary spiracles. Similar processes
extend inward from the walls of the thorax to strengthen it or to
give attachment of muscles. Such processes in general form the
32 THE ANATOMY OF THE HONEY BEE.

entoskeleton and are individually called apodemes. Those of the
head constitute the entocranium, those of the thorax the entothoraz.

The side walls of the fossa of the proboscis form two high, thin,
vertical plates, as seen from the interior of the head (fig. 11), in
front of the mesocephalic pillars. The posterior edge (d) of each
of these plates is so much thicker than the rest of it in the worker
that it appears at first sight to be a separate rod. Its upper end
projects above the body of the plate as a free arm (e) to which is
articulated the basal piece of the maxilla (Cd). It thus constitutes
the maxillary suspensorium. (Macloskie includes under this term
both the arm of the cranial wall and the cardo of the maxilla.)

The head of the drone (fig. 11 B) presents, besides the parts de-
scribed, a thin plate (f) depending from the vertex of the cranium
along the line between the compound eyes.

Besides these apodemes of the cranial wall itself there are others
which project into the head cavity from the bases of the appendages
to afford points of insertion for their muscles. These are specially
developed in connection with the mandibles and will be described in
the discussion of these organs. Still other internal chitinizations are
developed in the walls of the pharynx, but these likewise will be
described later.

2, THE ANTENN2Z AND THEIR SENSE ORGANS.

The antenne of the bee are the two slender, jointed appendages
movably attached to the center of the face, where each is inserted
into a circular membranous area or socket just above the upper part
of the clypeal suture. Their general shape and position are shown
by figures 9 A, 11 A, and 19, Ant. Each is seen to consist of two
parts, forming a prominent elbow with each other, and usually so
held that the first or proximal part extends outward and upward
from its frontal attachment and carries the other in a pendent posi-
tion from its distal end. The first part thus forms a basal stalk,
called the scape (figs. 9 A; 19, Scp), consisting of a single joint
inserted into the antennal socket of the front by a prominent basal
condyle bent toward the face. ‘This articular knob is attached to
the rim of the socket by a circle of membrane, but it is also pivoted
on a slender peglike process projecting upward from the lower edge
of the socket. Hence, while the flexible membrane allows each
antenna to revolve freely in any direction, the latter is at the same
time held firmly in position by the pivot. The antenne are moved
by special sets of muscles inserted upon their bases within the head.
The second or distal division of the antenna is cylindrical and longer
than the first, forming a flexible flagellum (fig. 9 A; 19, #7) hanging
downward from the distal end of the scape. It is composed of 11
THE HEAD OF THE BEE AND ITS APPENDAGES. 33

small joints in the worker and queen and of 12 in the drone. The
male antenna thus consists of 13 joints in all, while that of the female
has but 12. The first joint of the flagellum is freely articulated to
the scape, but the others do not have much play upon one another,
though they give flexibility to the flagellum as a whole.

Each antenna is a hollow tube containing the large antennal nerve,
minute extensions of the tracheal system, and the small muscles which
move the segments upon one another.

Popularly the antenne of insects are known as the “ feelers,” be-
cause they are constantly moved about in all directions with a nervous
kind of motion as if the creature were feeling its way along by means
of them. In fact “ feelers” is a better name for these appendages
than the scientific term, for there can be no doubt that the sense of
touch is very highly developed in them and that by means of them
insects acquire a great deal of information concerning their surround-
ings and their companions. Moreover, a large mass of evidence
derived from experiments shows unquestionably that the organs of
smell also are located upon the antenne in a great many if not all
insects, while some investigators believe that in some species they
carry in addition the organs of hearing.

The study of the senses of insects is a most elusive subject, and
becomes more so the more we ponder on the results of experiments.
In the first place, it is manifestly impossible for us to acquire any
real knowledge of an insect’s sensations, for what is to us an odor,
a taste, a color, or a sound may be something quite different to such a
differently organized creature. We can, however, by experiments
determine that some things which give us the sensation of an odor
are perceived also by insects when placed near them. Also it can be
shown that some of them distinguish substances of different taste in
their food, and likewise that they perceive movement and distinguish
the colors and in a vague way the outlines of objects. Furthermore,
it is known that some of their perceptions are more delicate than ours,
and that some insects at least see color where we see none. They may
even possess senses of which we have no conception.

Hence, while it can be positively stated that insects perceive differ-
ences of touch, taste, smell, sound, and light, and act accordingly, we
can not say what the sensations they acquire are like. In fact we
do not know that they have conscious sensations at all. What looks
like an action due to intelligent perception may be purely a reflex one,
unaccompanied by any sensation. This of course involves the ques-
tion as to whether such creatures or insects are possessed of conscious-
- ness or not—a question which can not be answered one way or the
other.

Understanding, then, that our knowledge of insect senses amounts
only to this, that what gives us the sensation of light, sound, taste,

22181—No. 18—10—_3
34 THE ANATOMY OF THE HONEY BEE.

touch, or smell makes also some sort of an impression on the insect
and varies in degree and kind much as it does in us, we may go on to
a study of the senses located on the antenne.

Here, again, however, we are confronted by a difficulty, for while,
at first thought, it seems very easy to hold some strong-smelling sub-
stance near the antenne of a beetle, ant, or bee and observe the evident
displeasure with which the creature turns away, yet we may be en-
tirely wrong if we conclude that the insect “smells” the substance
that repels it. Strong-smelling, volatile liquids may simply produce
pain in some of the delicate nerve endings of the antenne. Some
other kind of a being, experimenting on ‘our senses, might close up
our nose and mouth and prove that we smell by means of our eyes
on observing the blinking we should perform when strong formalin
or ammonia was held close to the face. Furthermore, irritant gases
and volatile liquids affect the mucous membranes of our noses and
throats in a way quite independent from the odor that we perceive,
and there is no reason why the same. may not be true of insects. As
pointed out by Forel, experiments on the sense of smell should be
made with odorous substances that the insect meets with in a state of
nature, which would be principally the materials it feeds on. In-
sects are indifferent to almost every mildly odorous substance not
used as food, which, however, does not prove that they do not smell
them.

Again, in many cases, it would be difficult to decide whether the re-
sults of an experiment should be accredited to smell or sight. For
example, every bee keeper knows that hungry bees are attracted to
honey a long distance from their hives, and it would seem almost self-
evident that they are guided by a sense of smell. Yet one might con-
tend that they find the honey by sight, as, indeed, is claimed by a
number of entomologists who have made experiments on the olfactory
powers of bees. This question has been decided in some other insects
by painting the eyes with some opaque substance or by removing the
antenhse, but the evidence is not conclusive on either side in the case of
bees.

Experiments made by a large number of competent investigators,
including Lubbock, Schiemenz, and Forel, have proved conclusively
that the organs of the sense of smell in insects are located principally
on the antenne. The most interesting of these experiments are per-
haps those which Forel (1903) made on carrion-feeding beetles. He
found the dead and putrid bodies of a hedgehog and a rat infested by
a swarm of these beetles belonging to several genera. He collected
more than 40 specimens from the carcasses and removed their an-
tenne. Then he placed them all at one place in the grass and moved
the dead bodies to a distance of 28 paces from the beetles where he
concealed them in a tangle of weeds. Examination the next day
THE HEAD OF THE BEE AND ITS APPENDAGES. 35

revealed the fact that not one of the mutilated beetles had found the
carcasses. Repeated experiments gave the same results—no beetle
without its antenns was ever found on the dead animals, although at
each examination new individuals of the several species were present.
It might be supposed that the mutilation itself distracted the beetles
to such an extent that they did not care to eat. In order to test this
point Forel next cut off all the feet on one side of the body from a
dozen intact beetles and changed the location of the dead bodies again.
The next day five of this lot were found on the carcasses.

The same results have been obtained from experiments on other
insects. Ants distinguish between their comrades and enemies by
means of their antennal sense organs. Males of the silkworm moth
and many other moths and butterflies perceive the presence of
the females and are guided to them by an evident sense of smell
located on the antenne, for they fail completely to find them when
these appendages are removed, although one immediately recognizes
a female when placed in contact with her.

Similar experiments have been made on the bee, testing the ability
of the workers to find honey hidden from their sight. The results,
according to Forel, seem, curiously enough, to indicate that bees can
perceive odors but a very short distance from their heads. Forel
found that hungry bees in a cage would pass and repass hundreds of
times within a few millimeters of some honey concealed from their
sight by a lattice without discovering it. They ate it greedily, how-
ever, when the lattice was removed, though it had been perfectly
accessible to them all the time. Forel believes that “ bees guide them-
selves almost exclusively by vision,” and Lubbock holds the same
opinion. At the same time it would probably be a very difficult mat-
ter to convince many practical bee keepers that bees do not ‘ smell ”
from long distances. It is a well-known fact that at times when nec-
tar is scarce bees are attracted in large numbers to the houses of an
apiary where honey is stored, though, when the natural flow is suf-
ficient, they pay no attention to it. Tests of the olfactory sense should
undoubtedly be made under natural conditions. Bees inclosed in a
box with some honey concealed from their sight might not be able to
locate it in such close quarters though they might be smelling it all
the time. An odor in a room may so fill the air that it does not seem
to come from any particular direction and we ourselves would have
to exert our intelligence to discover its source.

While, then, it does not seem probable that bees have such limited
olfactory powers as some investigators claim their experiments indi-
cate, it may:be accepted as proved that the organs of smell are located
principally on the antennew. It has already been stated that the sense
of touch also is very highly developed on these organs, although in a
less sensitive degree it is distributed over most of the other parts of
36 THE ANATOMY OF THE HONEY BEE.

the body. It is again specially developed on the palpuslike append-
ages of the sting. (See figs. 36 and 37, StuPlp.) Sections of a bee's

A~Nyv

Fic. 12.—Antennal hairs and sense organs
(after Schiemenz). A, example of antennal
hairs (Hr) imbedded in cuticle (Ctl) but
having no nerve connection; B, hollow hair
containing prolongation of special cell (Cl) ;
C, D, straight and curved tactile hairs con-
nected with basal cells (Cl) and nerve fibers
(Nv); E, conical hair (Hr) sunken in a pit
(Pt) of the cuticle, probably an olfactory
organ; F, closed sac shut in by thin disc
(hr) on surface of antenna and containing a
delicately poised cell (Cl) with nerve con-
nection (Vv).

 

antenna show that there are
on its surface a great number
of minute structures of sev-
eral different kinds, though
all apparently are to be re-
garded as modified hairs,
which are undoubtedly the
sense organs. Now the difli-
culty arises of deciding which
of these to assign to the sense
of touch and which to the
sense of smell. Different au-
thors have made such differ-
ent interpretations of the
sense organs of insects that
the student attempting to get
information on the subject
from books must soon be dis-
couraged by their conflicting
statements. But it must be
realized that only intelligent
guessing is possible where
several senses are located on
the same part. In the case of
the bee some authors have
ascribed even a third sense,
that of hearing, to the an-
tenn, but there is little evi-
dence that bees possess the
power of hearing. The senses
of taste and touch are pos-
sessed by the mouth parts,
and some entomologists think
that they contain organs of
smell also. Thus, the organs
of sight are apparently the
only ones that can not be con-
fused with some other sense.

The best account of the
antennal sense organs of the

bee is that of Schiemenz (1883), whose drawings are here reproduced
(fig. 12) and whose text is the basis of the following descriptions.
The organs consist, as before stated, of modified hairs and their basal
THE HEAD OF THE BEE AND ITS APPENDAGES. 37

insertions which are connected with the ends of nerve fibers. Some
of them stand exposed on the surface of the cuticle while others
are sunken into, or entirely concealed within, pits of the integument.
In addition to these, there are two other kinds of special hairs on
the antenne which have no nerve connections, while, finally, the ordi-
nary hairs, such as are found on all parts of the body, occur also on
them, especially on the scape.

The special hairs not provided with nerve endings are of two
sorts. One is a solid curved or hooked hair (fig. 12 A, Hr) which
is simply articulated into a socket of the cuticle (Ct), while the
other (B) is hollow and is situated over a channel through the cuticle,
and contains a prolongation of a specially enlarged epithelial cell
(Cl) lying beneath it. These hairs can not be regarded as sensory,
since they have no communication with the central nervous system,
and it is not clear just what purpose they do serve.

The simplest sensory organ is a short, hollow, conical hair (C,
Hr) arising directly from the surface of the cuticle, over a wide
opening through the latter, and containing the end of a sensory cell
(Cl) connected with a nerve fiber (Vv), which goes into the main
trunk of the axial antennal nerve. A modified form of this organ
consists of a curved hair (D, H7) set into a small depression over
the cuticular channel. Such hairs are probably tactile in function;
that is to say, by means of them the bee can perceive that its antenn
are in contact with some surface. The general integument is too
thick and dense to allow of any sort of delicate touch sensation being
communicated through it, but if one of these movable hairs brushes
against an object the nerve within it must be at once stimulated.
Tactile or touch hairs are distributed especially over the outer sur-
face of the antenna and at its apex, but occur also scattered over
the other parts of the body and on the mouth parts.

Microscopic sections of the antenne reveal still other organs
which are not so apparent on the surface as the hairs just described.
One of these is shown at E of figure 12. It consists of a small pit
(Pz) in the integument, widened basally, and having a small papilla
on its floor, in whose summit is the opening of a still deeper cavity
which also expands toward its deeper end. This inner cavity is
almost filled up by a conical plug (H7) which arises from its floor
and ends just below the aperture into the outer pit. The plug con-
tains a thick nerve ending which arises from a ganglion cell con-
nected with the antennal nerve by a nerve’ fiber. Ten or more of
these sense organs occur on the terminal and the first three segments
of the flagellum. It is evident that each is simply a sensory hair
which has been doubly sunken into a cavity of the integument.
38 THE ANATOMY OF THE HONEY BEE.

As before stated, it has been conclusively proved by several investi-
gators that bees perceive odors, and it is said that if the antenne
are covered with shellac, bees can distinguish between distasteful
substances only by means of the proboscis. Schiemenz and most
other writers on the subject therefore conclude that the sunken cones
are the organs of smell, since, being below the surface, they could not
be organs of touch. Some other authors, however, among whom are
Cheshire, regard these inclosed cones as hearing organs. They sup-
pose that the sound waves of the air enter the pit, as into an ear
cavity, and these set up a vibration in the cone which stimulates the
attached nerve ending. However, the appearance of one of these
cones would suggest that it is too stable a structure to be affected
by sound waves, so the olfactory theory seems much more probable.

Finally, Schiemenz describes the most specialized of all the anten-
nal sense organs as a closed cavity (Pt) in the cuticle (Cé) extend-
ing into the hollow of the antenna as a long, curved, tapering sac.
This is shown at F of figure 12. A nerve (Nv) enters the lower
extremity of the pouch, expands slightly into a nucleated ganglion
cell (Cl), and then extends toward the top as a delicate spindle.
drawn out into a fine tapering point. The surface covering of the
pit is a thin layer of chitin presenting several cuncentric light and
dark rings surrounding a central disc (Ar). Sections show that this
appearance of rings is due to circular thickenings of the membrane,
and Schiemenz points out that the central disc is probably a modi-
fied hair, while the whole structure is to be regarded simply as a
modification of a tactile organ such as that shown at D with the
nerve-ending and its ganglion inclosed in a sac. These organs are
most abundant on the antennz of the drones, where they are situ-
ated, especially on the under surface, so close together that but little
space is left between them for the tactile hairs, while in the workers
and queens they are farther apart and are interspaced with many
tactile hairs. Hence, whatever sense they accommodate must be
much more highly developed in the males than in the females.
Schiemenz described these organs, as well as the sunken cones, as
organs of smell. He ascribed only the senses of touch and smell to
the antenne, and both Cheshire and Cowan concur in his view of the
closed pits. Arnhart (1906), however, argues that an organ of smell
must be open to the air in order to permit the ingress of odor par-
ticles. Such an organ is constituted by the sunken cones, but the
closed pits have nothing to recommend them for an olfactory func-
tion. Arnhart then further points out that the buried sacs, inclosing
a delicately poised nerve-ending and covered by an external tym-
panum, have all the mechanical elements of an organ of hearing.
He finally argues that bees must hear, since they produce special
sounds such as the piping of the queens, and that, since no possible
THE HEAD OF THE BEE AND ITS APPENDAGES. 39

organs of hearing have been discovered on any other part of the body,
some of the antennal sense organs must be auditory in function. His
conclusion from these premises is, of course, inevitable that the
closed sacs on the antennex are the hearing organs of the bee. What
invalidates the argument, however, is the fact that no one has yet
produced any actual evidence that bees perceive sound.

The following, then, may be stated as a general summary of the
evidence concerning the antennal senses and their sense organs in
the bee: (1) The antenne are highly sensitive to touch and are the
seat of the sense of smell. (2) They are covered by several kinds
of minute structures which are modified hairs containing special
nerve-endings. (3) By inference, it would seem certain that these
are the sense organs, but we can only form an opinion, based upon
their structure, as to which are tactile and which olfactory. (4) One
set of organs does not appear to belong to either of these categories
and their structure suggests an auditory function, but, in the absence
of evidence that bees hear, the purpose of these organs must be re-
garded as problematical.

3. THE MANDIBLES AND THEIR GLANDS.

The mandibles (fig. 9 A, J/d) are the dark, strongly chitinous
appendages of the head, commonly called the jaws, situated at each
side of the mouth, anterior to the base of the proboscis. In all in-
sects with biting mouth parts the jaws work sidewise, each being
attached to the head by an anterior and a posterior articulation.
They can thus swing in and out on a longitudinal axis in such insects,
as the bee, that carry the head with the mouth directed downward,
or in the same way on a vertical axis in those that carry the head
with the mouth forward.

Both mandibular articulations are of the ball-and-socket type,
although in the bee the socket is a very shallow one, the anterior
consisting of a condyle on the outer angle of the clypeus fitting
against a facet on the mandible, and the position of a facet on the
lower edge of the postgena receiving a condyle from the mandible.
The motion of the mandible is thus reduced to a hinge-joint move-
ment, and, on this account, insects can only bite and crush their
food; they can not truly chew it, since their jaws are incapable of
a grinding motion. Each mandible is, of course, as pointed out in
the introduction, really suspended from the head by a continuous
membrane between its base and the cranium, being simply a modified
saclike outgrowth of the head wall. The two articulations are pro-
ductions of the chitin on the outside of this membrane.

Figure 9 A shows the location and shape of the mandibles (.J/d)
of the worker as seen in a facial view of the head. Figure 11 A
40 THE ANATOMY OF THE HONEY BEE.

shows the appearance of the left mandible in side view, while the
right one is shown detached from the head in figure 13 A. The
mandibles differ conspicuously in size and shape in the three forms
of the bee as already described and as shown in figure 10 A, B, and C.
That of the worker is hollowed out somewhat on the distal half of
its inner face (fig. 18 A, Md) forming a spoon-shaped organ, the
edge of which is smooth and rounded. The mandibles of both the
queen (fig. 10 B) and the drone (C), however, are pointed at the
apex and have a conspicuous subapical notch. Those of the drone
are smaller than those of

      
   

RMcl
rn | either form of the female
a \ but: appear to be scpedially
Hi small on account of the
Vy

wl

vi

great size of the drone’s
head. The mandible of the
worker is undoubtedly to
be regarded as the special-
ized form, since the notched
mandible of the drone and
queen is of the ordinary
Hymenopteran type. Both
the drone and the queen
are, under normal circum-
stances, fed almost entirely
by the workers, and they
probably never have any

  
 

 

 
 
   

 

<a
wee Le Os
oe Sn

ay OY

    

ae
oe

 
     

Fic, 13.—A, right mandible of worker, anterior
view, with extensor and flexor muscles (HMcl
and RiJfci) and mandibular glands (1M@dGI1) at-
tached; B, corresponding view of mandible of
drone, with muscles cut off a short distance from
their bases.

use for their jaws as feed-
ing organs. The queen
needs her large, sharp-
pointed mandibles for bit-
ing her way out of the
thick wax cell in which
she is reared, but the
drone, on the other hand,

being reared in an ordinary cell resembling that of a worker, except
in size, is easily able to cut through the thin cell cap with his com-
paratively weak jaws. The workers, however, have numerous uses
for their mandibles, such as biting through the cell caps, eating
pollen, and modeling wax. The last is the especial function of
the worker mandible, and probably it is to accommodate this pur-
pose that it has acquired its specialized spoonlike shape.

Each mandible is moved by two sets of muscles within the head.
The outer one constitutes the extensor muscle (fig. 13 A, FAfcl) and
the inner the flexor muscle (RMcl). The latter is the stronger of
THE HEAD OF THE BEE AND ITS APPENDAGES. 4l

the two, since all the work of the mandible falls upon it, the extensor
being used simply to open the jaw. While these muscles have their
origins on the walls of the head, they are not inserted directly upon
the mandibles, but on large apodemes (fig. 13 A, Ap and RAp)
attached to the edges of the mandible.

A gland opens at the inner margin of each mandible between the
anterior articulation and the base of: the apodeme of the flexor
muscle (fig. 18 A and B, 7/MdG1). In the worker it consists of a
large sac covered with secreting cells lying within the front part of
the head between the clypeus and the compound eye (fig. 10 A,
1MdG1). These mandibular glands may be most easily studied by
removing the front as shown in figure 10 A, B, and C. In order to
do this, pull the head from the thorax and allow the prothoracic legs,
which will usually come off with the head, to remain attached to it.
Next melt a small hole in the bottom of a paraffin dish with a heated
needle and fasten the head face upward into this, the attached legs
helping to anchor the head in the paraffin. Cover the specimen with
weak alcohol and by means of sharp needles remove the part of the
front on either side between the clypeus and the lower half of the
compound eye in the worker and drone and the entire front of the
queen. In figure 10 the whole front is removed in all three forms in
order to expose other internal parts of the head.

The mandibular gland (14/dG1) is of greatest size in the queen
(fig. 10 B), though it is large in the worker (fig. 10 A and fig. 13 A),
but it is reduced in the drone (fig. 13 B) to a very small oval sac,
which is hidden by another gland (2@2) in front (fig. 10 C). It was
first described by Wolff (1875) as an olfactory mucous gland (Riech-
schleimdriisse) and was supposed by him to secrete a liquid which
was poured upon the roof of the mouth in order to keep this surface,
on which Wolff thought the olfactory organs were located, in a moist
condition capable of absorbing odor particles. There is absolutely
no evidence, however, of the presence of organs of smell in the mouth,
and furthermore, as pointed out by Schiemenz (1883), the gland
varies in the three forms of the honey bee according to the size of the
mandible, which is proportionately largest in the queen and smallest
in the drone. Of the three, we should expect the drone or the worker
to have the sense of smell most highly developed, and hence, even if
we did not know that the sense of smell is located in the antenna,
it would seem more reasonable to suppose that the glands of the
mandibles are connected in some way with the functions of these
organs themselves.

The mandibles, as already stated, are used for eating pollen and as
tools for manipulating and modeling wax. Therefore, according to
Arnhart (1906), since the queen does not eat raw pollen, the product
42 THE ANATOMY OF THE HONEY BEE.

of the mandibular glands must be intended for softening the wax
when it is worked in the jaws. The secretion of the glands is said
to be very volatile and strong smelling and to have an acid reaction.
It is probably entirely possible that it may have a solvent effect upon
the wax, or even, when mixed with it, change somewhat the chemical
composition of this substance; in fact, some investigators claim that
the wax of the comb differs chemically from that freshly taken from
the wax plates. Even this explanation, however, does not seem en-
tirely satisfactory, for the only occasions on which the queen has any-
thing to do with wax is when she gnaws her way out of her cell after
hatching or bites her way into the cells of young queens in order
to sting them. However, these occasional uses by the queen of her
mandibles appear to be important enough to maintain the large size
of these organs in the queen, and it may be reasonable to assume that
the demand upon their glands is likewise a large one when it does
occur. Yet the mandibles of the
queen are toothed and sharp
pointed, which should provide her
with sufficient cutting power both
to emerge from her own cell and to
enter the cells of other queens, and
so, on the whole, the opinion of
Schiemenz that the secretion of the
= mandibular glands is merely sali-
Ge 2MdCl vary in function would seem to be
Fie. 14.—Internal mandibular gland the simplest explanation and the

(2MdGl) of worker, lying against inner 4 5

‘wall of postgena (Pge) and opening most logical one. However, an
(Det) at inner edge of base of man- actual test should certainly be made

dible. é

to determine whether the worker’s
manipulation of the wax with her mandibles produces any change in
it, and to discover whether the queen simply bites her way mechan-
ically through the wall of the cell or at the same time softens the wax
by a secretion from her mouth. The male in any case has little use
for his mandibles, and the glands.are so small that they must certainly
be functionless. ‘

A second mandibular gland (fig. 14, 24/dG7) is present in the
worker. It consists of a delicate, flattened, racemose mass lying
against the internal face of the wall of the fossa of the proboscis,
whose duct opens into the mouth cavity at the posterior inner edge
of the mandible. This gland was first described by Bordas (1895) as
the internal mandibular gland. According to him, it corresponds
with a similar gland in the Bombidee (bumblebees) and in the Ves-
pide (yellow jackets) and to the maxillary glands of other Hy-
menoptera. Nothing is known of its secretion.

 
THE HEAD OF THE BEE AND ITS APPENDAGES. 43

4. THE PROBOSCIS.

The conspicuous group of mouth appendages in the honey bee,
forming what is commonly known as the proboscis (fig. 9 A, Prd),

 

Fie. 15.—Mouth parts of the worker: A, tip of glossa, showing labellum (LbIl), guard
hairs (Hr), and ventral groove (k); B, same, from above; C, small piece of glossal
rod (r) with adjoining parts of walls (q) of glossal canal attached, showing ventral
channel (7) guarded by rows of hairs. D, parts forming the proboscis, labium in middle
and maxille at sides, flattened out, ventral view; E, cross section of glossa showing its
invaginated channel (Lum) and position of rod (r) along its dorsal wall, and likewise
position of channel (7) of rod along median line within the glossal channel; F, end of
mentum (Mt) and bases of ligula (Ly) and labial palpi (LbPlp), showing opening
of salivary duct (SalDO), dorsal view; G, lateral view of proboscis showing parts on
left side; IH, lateral view of glossa (Gils) with its rod (r) torn away at base showing
attachment of retractor muscles (2RMcl).

by means of which the bee takes up liquid food, consists of what cor-
respond with the maxillee and the labium of insects that feed on solid
44 THE ANATOMY OF THE HONEY -BEE.

food alone. By separating the parts of the proboscis a little (fig.
9 B) it will be seen that, while there are five terminal pieces present,
three of them arise from one median basal sclerite (J/¢), the two
wider lateral appendages (.J/z) being carried each by a separate lat-
eral basal piece (S¢). The median group constitutes the Zabium and
the separate lateral parts the maville.

If the reader will now turn again to figure 3 C (p. 17), which may
represent any generalized insect labium, and compare with it the
drawing of the bee labium, forming the median series of parts in fig.
15 D, he will at once be able to identify the parts of the latter. The
principal elongate median basal plate is the mentum (J/t), the small
triangular plate at its base is the submentum (Sm), and the two
jointed lateral appendages of the mentum are the ladial palpi
(LbPip), each carried by ‘a basal palpiger (Pig). It is only the parts
of the bee’s labium that le between the palpi which are actually
different from those in the generalized diagram where they consist
of the four lobes of the Vivyula (Gls and Pgl}. But even here it will
be seen that the two small lobes (Pg) in the bee’s labium, partly con-
cealed within the bases of the palpi, correspond with the paragloss«.
Hence we have only the long median appendage to account for and it
is unquestionably the representative of the glossw (Gls) which are
here fused together and drawn out into this flexible tonguelike organ.
In fact, a comparison with the mouth parts of other Hymenoptera in
which the elements are much less modified leaves no doubt of this
being the true interpretation of the bee’s labium. It is simply an
example of how nature constantly prefers to modify an already exist-
ing part to serve some new purpose rather than to create a new organ.

If, then, we bear in mind that the slender median appendage of
the bee’s labium represents the glossee of other insects, we may for
convenience cal] it the “tongue,” as it is popularly termed, or, since
it is a single organ, there is probably no grammatical objection to
calling it the glossa. The word “tongue,” however, to use it prop-
erly, should be applied to the true /ingua or hypopharyna (fig. 3 C
and D, Hphy) which arises from the upper surface of the labium.
Many of the older entomologists, adopting the notion from Kirby
and Spence, who defined the term in 1826, regarded the glossa of
the bee as the homologue of the lingua in other orders. Even Pack-
ard in his Text-book of Entomology calls the glossa the “ hypo-
pharynx.” Cheshire named it the “ligula,” and his mistake has been
perpetuated by several other writers on bee anatomy, including Cook
and Cowan. The term /iguia properly includes both the glossa and
the paraglosse, or should signify the basal piece from which these
four lobes arise (fig. 8 C, Zg), so that it can not be applied to the
glossa alone.
THE HEAD OF THE BEE AND ITS APPENDAGES. 45

The derivation of anatomical names counts for nothing in their
application—this must be determined by scientific usage and priority.
Thus, glossa is the Greek word for “tongue,” but it was first applied
in entomology to the median lobes of the labium; //ngua is its equiva-
lent in Latin and was first given to the true tongue or hypopharynx
in insects; Uégudu is a diminutive derivative from “lingua” and has
come to be applied collectively to the terminal parts of the labium
beyond the mentum but not including the palpi. Hence, all these
words mean the same thing by their origins, but their anatomical
applications should be carefully distinguished. In this paper there-
fore the slender median appendage ((/s) of the labium will be
called the glossa, or, for convenience, the tongue, but with the strict
understanding that the organ in question is not the true tongue.
This latter should be called the “ hypopharynx,” but, as will be shown
later, it is absent in the bee.

The glossa of the bee (figs. 9 B; 11 A and B, and 15 D, F, and G,
Gis) is covered with long hairs which increase in length toward the
end. The tip is formed of a small spoon-shaped lobe, the /abellwm or
bouton (LbL), which is covered by short delicate processes branched
at their ends (fig. 15 A and B, Zb/). The long hairs of the glossa
are arranged in circles and the transverse rows of hair bases give
the tongue a multiarticulate appearance. Surrounding the dorsal
side of the base of the labella and forming two short subterminal
rows on the ventral side of the glossa are a number of stiff, out-
wardly curved, spinelike hairs (47). These hairs have been de-
scribed as taste organs, but their appearance would suggest that they
are simply protective spines guarding the delicate tip of the tongue.
Between the two ventral rows of these spines is the termination of
a groove (A, 4) which extends along the midline of the under sur-
face of the glossa (D, /:) to its base (fig. 9 B, &). The cleft of this
groove is covered by two fringes of converging hairs whose tips are
inclined also toward the tip of the tongue.

Let us now return to a study of figure 15 D. The series of lateral
pieces as already explained are the maxille. A comparison with
figure 3 B representing a generalized maxilla will show that these
organs in the bee have suffered a greater modification than has the
labium, but the parts can yet be quite easily made out. The main
basal plate (St) is the combined stipes, subgalea, and patpifer, the
basal stalk is the cardo (C’d), and the little peglike process (J/rPlp)
at the outer end of the stipes is the greatly reduced mawillary palpus.
Hence, we have left only the terminal bladelike lobe (J/2) to account
for, and it is evident that it must be either the galea or the lacinia
(see fig. 3 B, Ga and Le) or these two lobes combined. Here again
a comparative knowledge of the mouth parts of Ilymenoptera comes
46 THE ANATOMY OF THE HONEY BEE.

to our aid and shows clearly that the part in question is the outer
lobe or galea, ‘for the inner one becomes smaller and smaller in the
higher members of the order and finally disappears.

The base of the submentum is connected in the bee with the upper
ends of the cardines by a flexible, widely V-shaped band, the Zorum
(Zr). The posterior angle of the submentum rests in the apex of the
lorum, while the tips of the loral arms are movably articulated with
the distal ends of the cardines. The name “lora” was given to this
structure by Kirby and Spence, but “lorum” is more correct, since
this is the Latin form of the word (meaning a thong or lash). Some
recent entomologists have spoken of the structure as consisting of
two rods, thus making the word do duty as a plural, but the thing
itself is all one piece. Cheshire and some others have incorrectly
applied the name to the submentum.

The lorum is peculiar to the Hymenoptera, and the reason for it
is clear when we examine the attachments of the parts of the proboscis
to the head. As already stated, the maxille and labium are sus-_
pended in a large cavity on the back of the head which may be called
the fossa of the proboscis (fig. 9 B, PrbFs). The maxille are articu-
lated by their cardines (Cd) to the maxillary suspensoria (fig. 11
A, e) at the upper edges of the side walls of the fossa. The labium,
on the other hand, is not attached to the solid walls of the cranium
but is suspended in the membranous floor of the fossa. This is to
afford it freedom of movement during feeding, but, in order to
give it more substantial support and to make the regulation of its
motions possible, the submentum is slung to the ends of the cardines
by the lorum.

The terminal lobes of the labium and maxille when not in use
are ordinarily folded down beneath the head against the mentum
and stipites (fig. 19). When, however, the bee wishes to imbibe a
thick liquid such as honey or sirup in large quantity, these parts are
straightened out and held close together so as to form a tube between
them leading into the mouth, the terminal joints of the labial palpi
alone diverging from the rest (fig. 11 A).

The action of the mouth parts while feeding may be observed quite
easily if some bees are given a small amount of honey and then
watched through a lens while they are eating. A most convenient
method is to put a few workers in a small screen-covered cage, such
as are used for queen nurseries, spread a small drop of honey on the
wire, and then place the cage under a simple microscope. It will be
seen that the maxille are held almost stationary but that the base
of the labium slides back and forth between the maxillary bases
with a very regular to-and-fro movement as if the honey were being
either pumped or sucked up into the mouth. It is probable that there
is a sucking force exerted by the pharynx (fig. 11 B, Phy) but not
THE HEAD OF THE BEE AND ITS APPENDAGES. 47

by the honey stomach (fig. 44, WS), which latter, as Cheshire re-
marks, could no more suck honey through the cesophagus than a
balloon could suck gas from a pipe. The liquid undoubtedly runs
up the temporary tube between the blades of the mouth parts first
by capillary attraction, but it must be greatly assisted along its way
to the mouth by the retraction of the labium. The load brought up
when this is pulled back is then sucked .into the mouth by the
pharynx while the labium immediately goes out again after more.
It acts thus as a sort of mechanical feeder and this function is prob-
ably derived from the lapping motion of the under lip in wasps and
hornets.

The mentum (fig. 15 D and G, J/t) is hinged freely upon the
submentum (Smt), the latter, as already described, is set into the
socketlike angle of the lorum, while, finally, the arms of the lorum
are articulated to the distal ends of the cardines of the maxille.
Now, when the labium is retracted by means of muscles attached to
the mentum, the submentum turns in the loral socket and assumes a
position at right angles to the mentum while the lorum itself turns
somewhat on its articulations with the cardines. This great freedom
of motion is permitted by the loose membrane of the fossa in which
both the maxille and the labium are suspended.

The observer, however, can not fail to note that beside this motion
of the entive labium the tongue itself, or glossa (@/s), performs a
conspicuous independent movement of its own. It is by far the most
active member of the mouth parts during feeding, being actively
thrust out and retracted while its tip is constantly moved about in
a way suggestive of its being delicately perceptive of taste or touch
or perhaps to both of these senses. So great is the retractile power
of the tongue that its tip, which normally extends far beyond the end
segments of the labial palpi, can be drawn back entirely within the
latter. This contractile activity appears at first sight to be due to
elasticity, but a closer examination will show that the entire ligula,
i. e., the paraglosse (Pgl) as well as the glossa (Gls), moves back
and forth and that the action is due to a retraction of the base of the
ligula (fig. 15 F, Zg) into the anterior end of the mentum (.I/¢).
The ligula is supported on a membranous cone at the end of the
mentum whose walls are strengthened by three thin chitinous plates,
two above (F, p) and one below (D, 0). By the contraction of
muscles situated within the mentum (fig. 16, 7?J/c7) and inserted
upon the base of the ligula the latter is pulled into the end of this
cone whose walls, including the chitinous plates, simply turn inward.

But the tongue does possess also a contractile power of its own by
means of which it actually shortens its length. <A flexible rod arising
from the median ventral supporting plate (fig. 15 D, 0) of the ligula
extends throughout its length. The base of this rod is curved down-
48 THE ANATOMY OF THE HONEY BEE.

ward and has two muscles attached to it. This is shown by figure
15 H, where the rod (7) is torn from the glossa (Gls) basally so as
to show the muscles (2Rd/cl) inserted upon it and its connection
with the plate (0). By the contraction of the muscles the rod bends
at its base and is drawn back into the mentum. The glossa thus
shortens and becomes bushy just as does a squirrel’s tail when one
attempts to pull the bone out of its base.

The protrusion of the parts is due to the pressure of blood driven
into the ligula from the mentum, while probably the glossa extends
also by the straightening of its rod as the muscles relax. Wolff ”
described a protractor muscle at the base of the ligula. The rod of
the tongue is certainly not in itself contractile, as supposed by
Cheshire, who looked for evidence of muscular striation in it. It has
mostly a transparent and cartilaginous appearance, but is presumably
chitinous.

The mouth parts, their action in feeding, and the muscular mech-
anism by which they are moved have been elaborately described
and illustrated by Wolff (1875) in his monograph on the organs of
smell in bees. Most unfortunately, however, Wolff’s paper was
written to show that the seat of the sense of smell is in the mouth,
a most erroneous notion, and the title of his paper based on this
notion has caused little attention to be paid to this work on the mouth
parts of the bee, which is one of the best anatomical treatises ever
produced on the mouth parts of any insect.

It still remains for us to describe the details of the glossa and its
particular function in feeding. The tongue is not a solid appendage
nor yet is it truly tubular. A.compromise is effected by the longi-
tudinal groove (fig. 15 A and D, &) on its ventral surface which
expands within the tongue into a large cavity occupying half of its
interior (E, Zum). The glossal rod (7), which has already been
mentioned, lies in the dorsal wall of this channel and is, hence,
really not an internal but an external structure. The rod is itself
grooved along its entire ventral length (E, 7) and this groove again °
is converted into a tube by two rows of short hairs which converge
from its margins. The lips of the ventral groove of the glossa are
so deeply infolded that its cavity is almost divided along the midline.
Hence, the glossa might be described as containing three channels—
a small median dorsal one (2) and two large latero-ventral ones
(Lum).

The glossal rod (fig. 15 C, 7) is very flexible but not contractile, as
already stated, and is mostly clear and cartilaginous in appearance, ©
its ventral groove (Z) alone being lined by a deposit of dark chitin
(fig. 15 C and E). Its shape in section is sufficiently shown by the
figures. The walls of the large channels of the proboscis consist of
a delicate membrane (C and E, g) covered with very small hairs.
THE HEAD OF THE BEE AND ITS APPENDAGES. 49

The entire ventral cavity (Lum) with the rod (7) can be evaginated
through the ventral cleft (%) by blood pressure from within. As
Cheshire points out, this permits of the channels being cleaned in
case of clogging by pollen or any foreign matter.

It is supposed that these glossal tubes are of especial service to the
bee by enabling it to take up the smallest drops of nectar--quantities
that would be lost in the clumsy tube formed between the parts of
the jabium and the maxille. The suction must be in large part
capillary attraction, but here again the shortening of the glossa by
the retraction of its rod must squeeze the contained nectar out of the
upper ends of the channels where it is received upon the ventral flaps
of the paraglosse (fig. 15 F, Pgl), from which it runs around the
base of the tongue (Gis) within the paraglosse to the dorsal side of
the mentum (J/¢) and so on to the mouth. ;

The maxille and labium of both the queen and the drone (fig. 11
B) are smaller and weaker than those of the worker, and neither of
these two forms is capable of feeding itself to any extent. Ifa
hungry queen be given some honey she attempts to eat it and does
imbibe a small quantity, but at the same time she gets it very much
smeared over her head and thorax.

The mouth is hard to define in insects; practically it is the space
surrounded by the bases of the mouth parts, but strictly speaking it
is the anterior opening of the alimentary canal situated behind the
bases of the mouth parts (fig. 19, 17th). Yet the enlargement of the
alimentary canal (Phy) immediately following this opening is never
spoken of as the mouth cavity but is called the pharynx. On the
other hand the so-called epipharynx (Z’phy) and hypopharynx
(absent in the bee) are located in front of this opening and are con-
sequently not in the pharynx at all, the former being attached to the
under surface of the labrum and clypeus, while the latter is situated
on the upper surface of the base of the labium. These and numerous
other inconsistencies in the nomenclature of insect morphology have
to be endured because the parts were originally named for descrip-
tive purposes by entomologists who were not familiar with scientific
anatomy. In this paper the term mouth will be applied to the true
oral opening (fig. 19, Mth). The space in front of it between the
bases of the mouth parts may be called the preoral cavity.

The duct of the salivary glands of insects in general opens upon the
base of the labium in front of the hypopharynx. In the honey bee
the salivary opening is on the dorsal side of the base of the ligula
between the paraglosse (fig. 15 F, SalDO). This alone would show
that the glossa is not the hypopharynx of the bee, as many authors
have supposed, for otherwise the opening of the salivary duct should
be ventrad to the base of the glossa. In fact, this makes it clear that

22181—No. 18—10—_4
50 THE ANATOMY OF THE HONEY BEE.

the bee does not possess a hypopharynx. There is, however, a con-
spicuous chitinous plate located on the anterior part of the floor of the
pharynx (fig. 19, s) having two terminal points hanging downward
over the lower lip of the oral aperture, but, although this plate is truly
hypopharyngeal in position, it is not the homologue of the organ
called the hypopharynx in other insects. It is variously developed
in all Hymenoptera, being simply a chitinization of the floor of the
pharynx, and should be called the phar yngeal plate (Schlundbein of
Wolff). It will be more fully described in connection with the alli-
mentary canal. Ifa hypopharynx were present it should be situated
on the upper side of the labium (see fig. 3 D, phy) but there is here
present only a plain arched membranous surface in the honey bee
and other typical Hymenoptera.

The external location of the salivary opening enables the saliva
to be mixed with the food before the latter enters the mouth. This
is necessary in insects since the jaws are also on the outside of the

SalDO

TMcl

 

Fic. 16.—Median section through distal half of mentum (Mt) and base of ligula (Lg)
of worker, showing opening of salivary duct (SalDO), and muscles connected with
ligula and the ‘salivary syringe’ (¢).

mouth, and whatever chewing or crushing the food receives from

them is consequently done in the preoral cavity.

In some insects the saliva is used for other purposes than diges-
tion. For example, the saliva of some predaceous insects with pierc- '
ing mouth parts belonging to the order Hemiptera is poisonous, and
when one of these insects “bites,” the saliva is injected into the
wound by a special pump. The bite of the mosquito is made painful
likewise by an irritant secretion from a part of the salivary glands.
Bees appear to have the power of letting their saliva run down the
tongue when necessary to dissolve a hard substance like sugar and
render it capable of being taken up in solution, for they do not eat
sugar with their mandibles. Moreover, there is even a sort of pump
or so-called “salivary syringe” at the termination of the salivary
duct in the ligula, by means of which the secretion can be forcibly
ejected from the opening.

The salivary opening on the base of the ligula (fig. 15 F, SalDO)
leads into a deep transverse pit with collapsible cartilage-like walls
having its deepest part turned horizontally toward the base of the
THE HEAD OF THE BEE AND ITS APPENDAGES. 51

labium (fig. 16, ¢). The salivary duct (Sal?) bends downward in
the anterior part of the mentum (J/¢) and opens into the posterior
end of the pit (¢). When the retractor muscles ({@J/cl) of the
ligula pull the latter back into the mentum the lips of the salivary
pit must necessarily be closed. The simultaneous contraction of the
elevator muscle (w) attached to the roof of the horizontal part of the
pit must expand the latter and suck the saliva from the salivary duct.
When, finally, these muscles relax and the ligula is driven out by
blood pressure in the mentum, probably produced in part by the
contraction of its dorsal transverse muscles (7'Mcl), the saliva in
the temporarily formed bulb must be squirted out upon the base of
the tongue. Wolff (1875) calls each dorsal longitudinal muscle of
the mentum (/@iMcl)—the two inserted upon the basal hooks (n) of
the glossa (fig. 15 H and fig. 16)—the retractor lingue longus. The
large ventral retractor muscle of each side (2Rd/cl) he calls the
retractor lingue biceps since its anterior end divides into two parts,
one of which is inserted by a tendonous prolongation upon the base
of the glossal rod (fig. 15 H and fig. 16, 7) and the other upon the
base of the ligula. The use of the word “ lingua” in these names is
objectionable because, as already explained (page 45), the lingua is
properly the true tongue or hypopharynx. “ Ligule ” should be sub-
stituted for “ lingue.” The dilator muscle (fig. 16, v) of the salivary
pit (¢) is termed the protractor lingue by Wolff because, as he sup-
poses, when the ligula is pulled back into the mentum the position
of this muscle is reversed, so that a contraction of its fibers would
help to evert the ligula.

The glands that furnish the saliva lie within the head and the
thorax and will be described later in connection with the alimentary
canal and the process of digestion.

Ephy Lm

  

Fic. 17.—Epipharynx (Ephy) and labrum (Lm) of worker: A, ventral view; B,
anterior view.

5. THE EPIPHARYNX.

The epipharynx of insects in general may be described as a dorsal
tongue, it being a median lobe developed on the roof of the preoral
cavity from the under surface of the clypeus or labrum and situated
opposite the hypopharynx.
52 THE ANATOMY OF THE HONEY BEE.

The epipharynx of the bee is a large three-lobed appendage de-
pending from the roof of the preoral cavity just in front of the mouth
(fig. 19, Bphy). Seen from below it is triangular (fig. 17 A) with

, the apex forward. Its median lobe has the form of a
B A» high, vertical, keel-like plate, while the lateral lobes

" ; are rounded but have prominent elevated edges con-

?. iy verging toward the front of the keel. The appearance
y in anterior view is shown by figure 17 B. Situated
eons on the posterior parts of the lateral lobes are a num-

ably of taste, ber of sense organs, each consisting of a small cone

ce *P** with a pit in the summit bearing a small hair (fig. 18).

These are regarded as organs of taste.

Wolff (1875) made a most thorough study of the epipharynx,
which he called the “palate sail” (Gawmensegel) on account of the
high median crest. His drawing is the standard illustration of the
organ found in nearly all boule on the anatomy of the honey bee

 

he .
SS

tnt y~ LoPlp

Fic. 19.—Median longitudinal section of head of worker, but with entire labium attached,

showing internal organs except muscles and brain.

and in most works on general insect anatomy and the sense organs.
Wolff, however, regarded the sensory cones as having an olfactory
function, and this led him to erroneous conclusions regarding the
functions of several other organs. For example, he thought that
the mandibular glands poured a liquid upon the surface of the
J THE THORAX AND ITS APPENDAGES. 58

epipharynx which kept it moist and capable of absorbing odor
particles, while he ex- is
plained the inhalation ggg,
of the latter into the ~ Fee
preoral cavity as
brought about through
the contraction of the
air sacs situated about
the mouth. Wolff’s
anatomical researches
are without doubt
some of the best ever
made on the bee, and
it is due to his mis-
taken idea of the loca-
tion of the sense of
smell, which, as al-
ready explained, is on
the antenna, that we
have received from
him a most excellent
account and detailed
drawings not only of
the epipharynx but of
the mandibular glands,
the mouth parts, the y4
salivary “ pump,” and
the respiratory organs.

ten

 

IV. THE THORAX AND
ITS APPENDAGES.

1. THE STRUCTURE OF
THE THORAX.

The apparent thorax
of the bee (fig. 20,
T,-IT, and fig. 21)
and of most other
Hymenoptera is not
exactly the equivalent
of the thorax in other
insects. The middle
division of the body,
so conspicuous in this
order, consists not only of the three leg-bearing segments, which alone

Fic. 20.—Dorsal view of ventral walls and internal skele-
ton of body of worker.
54 THE ANATOMY OF THE HONEY BEE.

constitute the thorax of all other insects, but also of the first ab-
dominal segment. The conspicuous necklike constriction posterior to
the base of the hind legs (fig. 21, Pd) is, therefore, between the first
and the second abdominal segments (fig. 1, 77 and JIT).

The thorax of the honey bee at first sight looks entirely different
in structure from that of all other insects except related Hymenoptera,
in the higher families of which group it is more highly modified than
in any other order of the whole series of insects. When, however, we
examine the thorax of one of the lowest members of the Hymenop-
tera, such as a sawfly, we are surprised to find that, in each segment,
the structure agrees very closely with our ideal diagram of a general-

ized thoracic

segment (fig. 4).
The three seg-
ments are per-
fectly distinct,

  
    

 
     
  
    
   

WP.
3 and the first
IT abdominal seg-
geod ment, while it
S= Z may be clearly
Vig EN eZ | dt
(SSS separated from
CE pb ST > Ps the rest of the

 
 

\ abdomen, is not
fused into the
thorax so as to
appear to be a
part of it. Tf,
now, we exam-
ine representa-
tives of several
families inter-
mediate between
the sawflies and
the bees, the line of specialization that has produced the bee thorax
becomes perfectly evident. The principal features in these modifi-
cations are the following:

(1) The lateral and ventral parts of the prothorax (figs. 20 and 21,
Eps, and S,) are suspended loosely in a large membranous area
which is continuous anteriorly as the neck. They thus form a sort
of suspensorium for the front legs, which appears detached from the
rest of the thorax. (2) The protergum (7,) is solidly attached to
the anterior edge of the mesothorax and its lateral parts extend
downward till they meet on the venter behind the prosternum (figs.
20 and 21). (3) The postnotum (postscutellum) of the mesothorax
(figs. 22, PV; 28 A, PN.) is entirely invaginated into the cavity of
the thorax and is reduced to the form of two lateral arms of the large

Fic. 21.—Thorax of worker, left side, with intersegmental lines
somewhat exaggerated, showing prothorax (71, Eps, Ca),
mesothorax (T2, Eps,, Epmez, Se, Caz), metathorax (Ts, Pls,
pls, Cas) and propodeum or first abdominal segment (IT).
THE THORAX AND ITS APPENDAGES. 55

internal postphragma (Pph) which has no median tergal connection
at all. (4) The metatergum (figs. 21 and 23 A, 7,) consists of a
single narrow plate. (5) The metapleurum (fig. 21, Pl, and pl,)
shows no trace of a division into episternum and epimerum, but is
divided into an upper (P2,) and a lower (pl,) pleural plate. (6)
The first abdominal tergum (fig. 21, 77) is solidly attached to the
metathorax and forms an intimate part of the thoracic mass.

We shall now proceed with a more detailed account of the thorax,
and the reader should occasionally turn back to figure 4 (p. 19) in
order to keep clearly in mind the parts that make up a generalized
thoracic segment.

The parts of the prothorax are so separated from each other that
they appear to belong to different segments. The protergum (fig. 21,
7,) forms a collar completely encircling the front of the mesothorax.
On each side a large lobe (w) projects posteriorly as far as the base
of the front wing and constitutes a protective shield over the first
thoracic spiracle. The tergum presents a median transverse groove,
dividing it into an anterior and a posterior part, which parts may
be called the scutum (fig. 23 A, 7',, Sct) and scutellum (Sel). The
propleurum (figs. 20, 21, #ps,) consists of a large plate presenting
both a lateral surface (fig. 21) and a ventral surface (fig. 20). On
account of the position of the coxal articulation (fig. 21) this plate
would seem to be the anterior pleural plate alone (see fig. 4), which
is the episternum. In some Hymenoptera the epimerum is repre-
sented by a very small plate on the rear edge of the episternum.
The anterior ends of the two episterna form knobs which loosely
articulate with the occipital region of the head (figs. 11 B, 20, and
91). Lying just ventrad of each is a slender cervical sclerite (fig. 21,
mt). The prosternum (S8,) is shown by figure 20. It carries a large
entosternum (/’u,), forming a bridge over the nervous system behind
the prothoracic ganglion (fig. 52).

The mesotergum, as seen in its natural position (fig. 21, 7’,), consists
of a large anterior scutum (Sc?¢,) and of a smaller but very prominent
posterior scutellum (Scl,), separated by a very distinct suture (7).
The scutellum has two latero-anterior areas partially separated from
the median area by sutures. When the mesotergum is detached from
the rest of the thorax (fig.22) it is discovered that there is attached
laterally to the scutellum a large posterior internal part, which does
not show on the sutface at all. This is the representative of the
postscutellum (Psel) and its phragma (Pph) constituting the post-
notum (PV) of our diagrammatic segment (fig. 4). The proof of
this, again, is to be derived from a study of the lower Hymenopteran
families. In some of the horntails (Siricide) the postnotum or
postscutellum is a prominent plate on the surface of the dorsum be-

hind the scutellum. In Sérev (Siricide) this plate is sunken below
4
56 THE ANATOMY OF THE HONEY BEE.

the general surface and mostly concealed between the mesothorax
and the metathorax. In higher families such as the Pompilide the
postnotum of the mesotergum is entirely concealed by invagination,
but it still carries a very large phragma. When, now, we come to
the highest members of the order we find that the median part of the
postnotum in the mesothorax is gone entirely and that it is repre-
sented only by the lateral arms (figs. 22, PV, 23 A, PN.) carrying
the large, purely internal postphragma (Pph).

The mesopleurum is large and consists principally of the episternum
(fig. 21, Z’ps.), which, however, is continuously fused with the meso-
sternum (figs. 20 and 21, S,). The pleural suture (fig. 21, PS,) is
short and sinuous and does not reach more than half way from the
wing process to the base of the middle leg. The epimerum is reduced
to a small double plate lying above the episternum and posterior to
the wing process (figs. 21, Ypm,, and 24 A, Hpm and Epm). The
pleural ridge (fig. 24 B, PR)
is weak, but the wing process
(WP) is well braced by a num-
ber of accessory internal ridges.
One preparapterum (2P) and
one postparapterum (3P) are
present. Lying behind the
postparapterum is another
larger sclerite (fig. 24 A and
B, pn), whose anterior end is
Fig 22 tater, vey of uentewon, of articulated to the edge of the

show large internal postscutellum (post- @pimerum and whose posterior

net, 73), and i phraeme, (Pet) et tapering end is loosely asso-
ciated with the terminal arms
of the postnotum (fig. 22, PN and pn). This sclerite might be
regarded as the fourth parapterum, but it is much more probably
the representative of a small terminal bar of the postnotum present in
other Hymenoptera, such as Pepsis, which connects this tergal plate
with the epimerum, though in this genus it is not detached from the
main postnotal sclerite.

Both the mesosternum (fig. 20, S,) and the metasternum (S,) con-
tribute to the formation of a large entosternum (fu, ), which forms
a protecting bridge over the combined mesothoracic and metathoracic
ganglia (fig. 52) and affords attachment for theeventral longitudinal
muscles of the thorax (fig. 27, dmel).

The metathorax consists of a very narrow series of plates (fig. 21,
7',, Pl,, and pl,) compressed between the mesothorax and the first
abdominal tergum (/7’). Its back plate is a single, narrow, transverse
sclerite (figs. 21 and 238A, 7,) widening on the sides, where it carries
the wings by the two wing processes’ (fig. 283 A, AVP and PVP). The

 
THE THORAX AND ITS APPENDAGES. 57

ordinary tergal divisions seem to be entirely obliterated. The meta-
pleurum consists of a dorsal plate (fig. 21, PZ,) supporting the hind
wing and of a ventral plate (pl,) carrying the hind leg. These two
functions certainly identify these two plates as constituting together
the metapleurum, but there is absolutely no trace of a division into an
episternum and an epimerum. Once more, therefore, we have to go
back to the generalized Hymenoptera to find out what has happened.

psvct

qm OTT

eS

 
  

           

 

Fic. 23.—A, thoracic terga of worker separated from one another, showing protergum
(71), mesotergum (7',) and its internal postscutellum (postnotum PN,) and phragma
(Pphe), metatergum (73) and propodeum or first abdominal tergum (IT) ; B, ventral
view of principal or notal plate of mesotergum.

The answer is simple. Sirew has a typical metapleurum consisting of
an episternum and epimerum separated by a complete pleural suture.
In the higher forms this suture simply disappears, and consequently
the pleurum shows no traces of its original component plates. The
division into a wing-bearing and a leg-bearing plate is, therefore, a
purely secondary one.

None of the Hymenoptera has separate trochantinal sclerites (see
fig. 4, Zn), but, since the coxe are articulated ventrally to knobs
58 THE ANATOMY OF THE HONEY BEE.

(figs. 20 and 21, z) apparently belonging to the sterna, it might be
supposed that the trochantins have fused with the latter plates.

The posterior part of the thoracic mass (fig. 21) consists of the
first abdominal tergum (/7), which fits into the deeply concave pos-
terior edges of the metathorax and forms the peduncle (Pd) that
carries the rest of the abdomen (fig. 32). It consists of a single large,
strongly convex sclerite (figs. 21 and 23 A, /7) bearing the first
abdominal spiracles laterally (JSp) and having its surface divided
into several areas by incomplete sutures.

Many entomologists find it difficult to believe that this plate, which
so apparently belongs to the thorax, is really derived from the abdo-
men. But the proof is forthcoming from a number of sources. In
the first place, the thorax is complete without it and the abdomen is
incomplete without it, the latter having otherwise only nine seg-
ments. Again, if the plate is reckoned as 2 part of the thorax we

 

Fic, 24.—A, upper part of left mesopleurum of worker, external; B, inner view of same.

should have the anomaly of a thorax with three pairs of spiracles—
there being the normal two on each side situated, as they always are,
between the true thoracic segments. Furthermore, comparative anat-
omy shows us that in some of the sawflies (Tenthredinide) the first
abdominal tergum, while separated by a wide membranous space
from the second, is not at all incorporated into the thorax. In a horn-
tail such as Sire (Siricidee) the entire first abdominal segment is
fused to the posterior edge of the metathorax and is only loosely
joined to the next abdominal segment by membrane. This insect
affords, therefore, a most complete demonstration of the transference
of this segment from the rest of the abdomen to the thorax. Finally,
we have absolute proof of its abdominal origin based on a knowledge
of development, for it has been shown by Packard from a study of the
bumblebee that the first abdominal segment of the larva.is trans-
ferred during the pupal metamorphosis to the thorax and forms the
THE THORAX AND ITS APPENDAGES. 59

part under discussion. We hence see that not only the first abdomi-
nal tergum but the entire segment has undergone transposition,
though the ventral part has disappeared in all the higher families.
This transferred part has been named both the median segment and
the propodeum by writers who recognize it as belonging to the abdo-
men and not to the thorax.

The names current among systematists for the back plates of
Hymenoptera afford an excellent example of the errors that ento-
mologists may be led into through an ignorance of the comparative
anatomy of insects. They recognize the protergum as such and then,
knowing that there are yet two segments to be accounted for, they
call the mesoscutum the “mesonotum,” the mesoscutellum the
“scutellum,” the metatergum the “ postscutellum” (being unaware
that the true postscutellum is deeply concealed within the thorax),
while the first abdominal tergum is called the metathorax. Such
a nomenclature assigns both pairs of wings to the mesothorax. Too
many systematists working in only one order of insects do not care
whether their names are applied with anatomical consistency or not.

2. THE WINGS AND THEIR ARTICULATION.

In the study of insects the wings always form a most interesting
subject because by them insects are endowed with that most coveted
function—the power of flight. It has already been stated that the
wings are not primary embryonic appendages, but are secondary out-
growths of the body wall from the second and third thoracic seg-
ments. Therefore it is most probable that the early progenitors of
insects were wingless, yet for millions of years back in geological time
they have possessed these organs in a pretty well developed condition.
. Nearly all of the insect orders have some characteristic modifica-
tion of the wing-veins and their branches. None of them, however,
departs nearly so far from the normal type as do the Hymenoptera,
even the lowest members of this group possessing a highly specialized
venation. Before beginning a study of the Hymenopteran series
which leads up to the bee the student should first turn back to figure
6 (p. 22) and again familiarize himself with the generalized condi-
tion of the veins and the articular elements of the wing. By com-
paring, now, with this diagram the basal parts of the wing of a
sawfly (Itycorsia discolor, fig. 26 A) it will be easy to identify the
parts of the latter. Vein C has two little nodules (C, C) cut off from
its basal end which lie free in the axillary membrane. Yein Sc articu-
lates by an enlarged and contorted base (Sc) with the first axillary
(1A@), while vein # is continuous with the second (247). The next
two veins that come to the base and unite with each other are appar-
ently not the media and cubitus but the first and third anals (1:1 and
60 - THE ANATOMY OF THE HONEY BEB.

8A), since they are associated with the third axillary (3.lv). In this
species the subcosta (Sc) is entirely normal, but in the related horntail
(Sirex flavicornis, fig. 26 B) the enlarged basal part of the subcosta is
almost separated from the shaft of the vein, while the latter (fig. 25.A,
Sc) is short and weak. A study of the venation of this wing leads
us to believe that the vein which arises from the radius a short dis-
tance from its base is the cubitus (Cw). Therefore the basal part

 

D

Fig. 25.—Wings of Hymenoptera and their basal articular sclerites (1da@—-4A%): A, Sirer
favicornis, front wing; B, Pepsis sp., front wing; C, honey bee, front wing; D, honey
bee, hind wing.

of the media is either gone or is fused with the radius. Since we dis-
cover its branches in the distal field of the wing, arising from the
trunk of the radius, we conclude that the latter is the case. By this
sort of reasoning we may arrive at the Comstock and Needham inter-
pretation of the wing illustrated at A, fig. 25. From this it is evident
that the branches of both the radius and the media have been bent
back toward the posterior margin of the wing.
THE THORAX AND ITS APPENDAGES. 61

 

 

Fic. 26.—Basal elements of wings of Hymenoptera: A, base of front wing of a sawfly

(Itycorsia discolor) showing comparatively generalized arrangement of veins and
axillaries; L, bases of anterior veins of front wing of a horntail (Sirex flavicornis)
showing detachment of base of subcostal vein (Sc) from its shaft; C, corresponding
view of anterior veins in front wing of a tarantula-killer (Pepsis sp.), showing com-
plete absence of shaft of subcosta, but presence of basal part (Sc) fused with base of
radius (R); D, axillaries of anterior wing of honey bee worker; E, tegula of worker ;
I, base of anterior wing of worker showing absence of shaft of subcosta but’ presence
of scale (Sc) derived from its base; G, axillaries of hind wing of worker, the fourth ab-
sent in bee ; H, base of hind wing of worker, showing absence of costal and subcostal veins
and fusion of bases of subcosta (Sc) and radius (R) into large humeral mass; I, attach-
ment of front wing to scutum (Sctz) and scutellum (Scl2) of mesotergum; J, under view
of end of mesoscutellum (Scl.) showing attachment of both first (14@) and fourth
axillaries (J4a) to posterior wing process (PNP), an unusual connection for first axillary.
62 THE ANATOMY OF THE HONEY BEE.

Taking this wing of Sirex as a foundation let us proceed a little
higher and examine the wing of a Pompilid, such as Pepsis (figs.
26 C and 25 B). We observed that in Sirex (fig. 26 B) the basal
part of vein Sc is almost separated from the distal shaft. In Pepsis
(fig. 26 C) it is entirely a separate piece, to which is fused also the
base of vein &. Moreover, the shaft of Sc has disappeared entirely
(fig. 25, B). Thus there is at the humeral angle of the wing a large
chitinous mass (fig. 26 C, Sc and R) representing the fused bases
of both the subcosta and the radius, which is associated with
both the first axillary (7x) and the second axillary (2Az).

If now we proceed to a study of the front wing of the bee we
find that its basal characters (fig. 26 F) are more similar to those of
Strex (B), while its venation (fig. 25 C) resembles more closely that
of Pepsis (B). The subcostal scale at its base (fig. 26 F, Sc) is
not fused with the base of the radius, but the distal part of the
subcosta is gone (fig. 25 C), as in Pepsis. In the hind wing of the
bee (fig. 26 H) the bases of the subcosta and radius are fused into
one large humeral mass articulating with the first two axillaries
(1Av and 2Awv). The third axillary (34x) is well developed but
the fourth is absent. The venation (fig. 25 D) is reduced to a very
simple condition, but to one just the opposite from primitive.

The details of the axillaries in the two wings are shown by figure
26 D and G. The fourth (4.4) is well developed in the front wing
(D) and has a large accessory sclerite (y) connected with it, upon
which is inserted a long slender muscle (fig. 28, cc). A very small
accessory sclerite (az) occurs close to the muscle plate of the third
axillary (3.la). These are called “accessory” sclerites because
they are of irregular occurrence in the wing bases of insects generally
and are developed in connection with the muscle attachments. Simi-
lar ones occur in the hind wing (G, aa) in connection with the
second (Aa) and third axillaries (3Az).

The front wing is attached to the posterior half of the side of
the mesonotum. The anterior notal wing process is bilobed (figs.
22, 23 A, T,, ANP) and is carried by the scutum, while the pos-
terior process (PVP) is carried by the scutellum and is mostly
hidden beneath the anterior wing process. The two wing processes,
in fact, are so close together that the first axillary articulates not
only with the first but also with the second (fig. 26 J). The axillary
cord (fig. 26 F, 1#C) arises from a lobe of the scutellum overlapped
by the lateral margin (I and J, Aw(). In the hind wing, where the
fourth axillary is absent, the third articulates directly with the
posterior notal wing process of the metatergum (fig. 23 A, 7,, PNP).

The base of the front wing is overlapped by a large scale (fig. 26,
E and I, 7g) called the tegula. It is carried by the axillary mem-
THE THORAX AND ITS APPENDAGES. 63

brane, to which it is attached between the humeral angle of the wing
base and the edge of the notum. The tegule are present in most in-
sects, generally on the base of each wing, but they usually have the
form of small inconspicuous hairy pads, as shown in the diagram
(fig. 6, 7g). In the flies, moths, butterflies, and Hymenoptera,
however, the tegule of the front wings develop into large conspicu-
ous scales overlapping the humeral angles of the bases of these
wings.

The motion of the wing in flight consists of both an up-and-down
movement and a forward-and-backward movement, which two com-
bined cause the tip of the wing to describe a figure-eight course if
the insect is held stationary. Corresponding with these four move-
ments are four sets of muscles. In the dragonflies nearly all of the
wing muscles are inserted directly upon the base of the wing itself,
but in other insects, excepting possibly the mayflies, the principal
muscles are inserted upon the thoracic walls and move the wing
secondarily. In the lower insects, such as the grasshoppers, crickets,
stoneflies, net-winged flies, etc., the two wing-bearing segments are
about equal in their development and each is provided with a full
equipment of muscles. In these insects the wings work together by
coordination of their muscles, although each pair constitutes a sepa-
rate mechanism. In such insects, however, as the true flies and the
wasps and bees the metathorax, .as we have seen in the case of the
bee, is greatly reduced, and what is left of it is solidly attached to
the mesothorax. In the flies the hind wings are reduced to a pair
of knobbed stalks having no function as organs of flight, while in
the bees the hind wings, which are very small, are attached to the
front wings by a series of hooklets on their anterior margins (fig.
25 D, Hk) which grasp a posterior marginal thickening of the
front wings. Moreover, when we examine the interior of the bee’s
thorax we find that the muscles of the metathorax are greatly
reduced or partly obliterated and that the great mesothoracic mus-
cles serve for the movement of both wings, thus assuring a perfect
synchrony in their action. Hence, it is clear that the union and
consolidation of the thoracic segments in the higher insects is for
the purpose of unifying the action of the wings.

The muscles of flight in the bee may be very easily studied by cutting
the thorax of a drone into lateral halves. The cavity of the thorax
is occupied almost entirely by three great masses of muscles. One
of these is longitudinal, median, and dorsal (fig. 27, ZMcl,), extend-
ing from the mesoscutum (Scé,) and the small prephragma (.1ph)
to the large mesothoracic postphragma (Pph,). A small set of
muscles (ZMc/,) then connects the posterior surface of this phragma
with the lower edge of the propodeum (/7). On each side of the
64 THE ANATOMY OF THE HONEY BEE.

anterior end of this great longitudinal muscle is a thick mass of
dorso-ventral fibers (Vd/cl) extending from the lateral areas of the
mesoscutum (Sct,) to the lateral parts of the mesosternum (S,). A
contraction of the vertical muscles must depress the tergal parts,
at the same time expanding the entire thorax in a longitudinal direc-
tion and stretching the longitudinal muscles. A contraction, then,
of the latter muscles (ZMcl) restores the shape of the thorax and
elevates the tergul parts. Remembering, now, that the wings are
supported from be-

LMcl, low upon the

Seta ON pleural wing proc-

S SS “Sel, esses and that each
is hinged to the

back by the notal

 

¥; As wing processes, it

is clear that a de-

! IT pression of the

# dorsum of the

Aph \-- \Y_}Peh2 = thorax must. cle-

VMele ay vate the wings and

ve Sane 4 Mel; that an elevation

hael’” Gor of the dorsum de-
mel

presses them—the

5) WORE ETE i pleural wing proc-
/ OS ’ i esses acting as the
VMel z Cx, : fulcra. Hence, the

Fic. 27.—Median section through thorax of drone, showing chief up-and-down
longitudinal muscles (LMcle) of mesothorax going from
mesotergal scutum (Sctz2) and small anterior phragma movements of the
(Aph) to posterior phragma (Pphz) of internal postscutel- wings are pro-
lum (postnotum) of same segment, also showing vertical
mesothoracic muscles (VMcl), and ventral longitudinal mus- duced by these
cles (Imel), and longitudinal muscles of metathorax great thoracicmus-
(LMcls) going from postphragma of mesothorax (Pphe) to é.
posterior edge of propodeum or first abdominal tergum (7). cles acting upon
By alternate contraction of dorsal longitudinal muscles and the shape of the
vertical muscles, roof of thorax is elevated and depressed,
causing wings to beat downward and upward respectively, thorax as a whole
being supported on fulcra formed by pleural wing processes pnd not directl
(fig. 28, WP.) of side walls of thorax. y

 

 

 

 

upon the wings
themselves. The vertical muscles are the elevators and the longi-
tudinal the depressors.

But besides being moved up and down the wings can also, as before
stated, be extended and flexed, i. e., turned forward and backward in
a horizontal plane upon the pleural wing process. The muscles
which accomplish these movements lie against the inner face of the
pleurum (fig. 28), and each wing is provided with a separate set.
The extensor muscle (Pifcl) is the most anterior and is inserted by
a long neck upon the preparapterum (2P). The latter is closely
THE THORAX AND ITS APPENDAGES. 65

connected with the anterior part of the base of the wing so that a
contraction of the muscle turns the wing forward and at the same
time depresses its anterior margin. For this reason the parapterum
and the extensor muscle have been called the pronator apparatus, and
the muscle is known also as the pronator muscle. In some insects
which fold the wings back against the body this muscle is a great.
deal larger than in the bee. The flexor muscle (RMcl) consists of
three parts situated upon the anterior half of the pleurum and in-
serted upon the third axillary ($47) by long tendonlike necks.
These muscles are antagonistic
to the extensor and by their
contraction pull the wing
back toward the body.

The mechanism which pro-
duces the wing motion thus
seems to be a very simple one
and may be summarized as
follows: Each wing rests and
turns upon the wing process
of the pleurum (figs. 24 and
28, WP) by means of the
pivotal sclerite or second axil-
lary in its base (figs. 26 F and
28, 2Am). It is hinged to the
back by the first and fourth
axillaries (fig. 26 F, 1Aa and
4Ax) which articulate with
the anterior and _ posterior

    
 

 
 
 

fips cl as
a

Fig. 28.—1nternal view of right pleurum of

notal wing processes (fig. 238
A, 7,, ANP and PNP), re-
spectively. The large vertical
muscles (fig. 27, Vifcl) of
the thorax depress the ter-
gum, which pulls down with
it the base of the wing and

mesothorax of drone, showing muscles in-
serted upon parapteral plates (2P and 3P)
and upon third axillary (3417). The wing
rests upon wing process of pleurum (WPe2)
by second axillary (24a); it is turned for-
ward and downward by the pronator muscle
(PMcl), inserted upon anterior parapterum
(2P) which is attached to costal head of
wing, and is turned back toward body by
flexor muscle (RMcl) inserted upon third

: ill Aw).
hence elevates the distal part— =“ "” pot

the fulcrum being the pleural wing process. The dorsal longitudinal
muscle (Zdfcl) restores the shape of the thorax, elevates the tergum,
and consequently depresses the wing. Extension and flexion of the
wing are produced by special muscles (fig. 28, PJ/cl and RJfcl) acting
upon its base before and behind the pleural wing process, respectively.

Besides these muscles there are several others (fig. 28) associated
with the wing whose functions are less evident. Most conspicuous
of these is a muscle occupying the posterior half of the mesopleurum
(aa) and inserted upon the outer end of the scutellum. This may

22181—No. 18—10——5
66 THE ANATOMY OF THE HONEY BEE.

be simply accessory to the large vertical sterno-scutal muscle (fig. 27,
VMcl). Another is a long slender muscle (bb) attached to the upper
end of the mesocoxa and inserted upon the postparapterum (3P).
This is sometimes termed the covo-axillary muscle. A third (cc) is
inserted upon the tip of the accessory sclerite (y) of the fourth
axillary and is attached ‘to the lateral arm of the large entosternum
of the mesothorax and metathorax.

3. THE LEGS.

The legs of the honey bee are highly modified for several special
purposes besides that of walking, but they are so well known and
have been so often described that it will not be necessary to devote
much space to them here.

The front legs (fig. 29 A) have a structure formed by the adjoining
ends of the tibia and the first tarsal joint, which is called, on account ,
of its use, the antenna cleaner. It consists (fig. 29 C) of a semi-
circular notch (dd) in the base of the first tarsal joint provided
with a comblike row of bristles. A specially modified, flat, movable
spur (ee), shown in ventral view at B, is so situated on the end of
the tibia (7b) that it closes over the notch when the tarsus is bent
toward the tibia. By grasping an antenna between the notch and
the spur and drawing it through the inclosure the bee is able to re-
move from this sensitive appendage any pollen or particles of dirt
that may be adhering to it.

The middle legs (fig. 29 D) present no special modifications of any
importance. It will be observed, however, that they, as well as the
other legs (A and F), have the first joint of the tarsus (17'ar) very
greatly enlarged.

The hind legs of all three forms, the worker (F), the queen (E), and
the drone (H), have both the tibia and the large basal segment of
the tarsus very much flattened. In the queen and drone there seems
to be no special use made of these parts, but in the worker each of
these two segments is modified into a very important organ. The
outer surface of the tibia (F, 7b) is fringed on each edge by a row of
long curved hairs. These constitute a sort of basket (Cb) in which
the pollen collected from flowers is carried to the hive. The struc-
tures are known as the pollen baskets, or corbicula. The inner sur-
face of the large, flat, basal segment of the tarsus (17ar) is pro-
vided with several'rows of short stiff spines (G) forming a brush by
means of which the bee gathers the pollen from its body, since it
often becomes covered with this dust from the flowers it visits for
the purpose of getting nectar. When a sufficient amount is accumu-
lated on the brushes it is scraped off from each over the edge of the -
tibia of the opposite hind leg and is thus stored in the pollen baskets.
Hence the worker often flies back to the hive with a great mass of
THE THORAX AND ITS APPENDAGES, 67

 

Fig. 29.—A, left front leg of worker, anterior view, showing position of notch (dd) of
antenna cleaner on base of first tarsal joint (1Tar) and of closing spine (ee) on end
of tibia (Tb); B, spine of antenna cleaner (ee) in flat view; C, details of antenna
cleaner ; D, left middle leg of worker, anterior view; E, left hind leg of queen, anterior
or outer view; F, left hind leg of worker, anterior or outer view, showing the pollen
basket (Cb) on outer surface of tibia (Tb); G, inner view of first tarsal joint of hind
leg of worker showing rows of pollen-gathering hairs and the so-called ‘‘ wax shears”
(ff) ; H, left hind leg of drone, anterior or outer view,
68 THE ANATOMY OF THE HONEY BEE.

pollen adhering to each of its hind legs. The pollen baskets are
also made use of for carrying propolis.

Between the ends of the hind tibia (70) and the first tarsal joint
(1Tar) is a sort of pincerlike cleft (F and G, f#) guarded by a row
of short spines on the tibial edge. This is popularly known as the
“wax shears” and it is supposed to be used for picking the plates
of wax out of the wax pockets of the abdominal segments. The
writer, however, has watched bees take the wax from their abdomen
and in these observations they always poked the wax plates loose

 

Fic. 30.—A, dorsal view of end of last tarsal joint of first foot (Tar), the claws (Cla),
and empodium (Hmp) of worker; B, ventral view of same; C, lateral! view of same,
showing empodium in ordinary position when not in use.

 

with the ordinary hairs or spines of the tibie or tarsi and then by
means of the feet passed them forward beneath the body to the
mandibles.

The last tarsal joint of each leg bears a pair of claws (E, Cla) and
a single median empodium (Emp). Each one of the claws is bi-
lobed, consisting of a long tapering outer point and a smaller inner
one (figs. 30 and 31). The claws of the worker (fig. 31 A) and the
queen (B) are only slightly different in details of outline, although
the claws of the queen are much greater in size than those of the
THE ABDOMEN, WAX GLANDS, AND STING. 69

worker, but the drone’s claws (C) are large and very strikingly
different in shape from those of either the worker or the queen.

The empodium (fig. 30 A, B, and C,_Zmp) consists of a terminal
lobe bent upward between the claws (C) and deeply cleft on its
dorsal surface (A), and of a thick basal stalk
whose walls contain a number of chitinous
plates. One of these plates is dorsal (A and
C, hh) and bears five very long, thick, curved
hairs projecting posteriorly over the terminal
lobe, while a ventral plate (B and C, #) is
provided with numerous short thick spines.
A third plate (A, B, and C, gg) almost
encircles the front of the terminal lobe, its
upper ends reaching to the lips of the cleft.

When the bee walks on any ordinary sur-
face it uses only its claws for maintaining a
foothold, but when it finds itself on a smooth,
slippery surface like glass the claws are of no
avail and the empodia are provided for such
emergencies as this. The terminal lobe is y,4 91-4, outer view of
pressed down against the smooth surface and hind claw of worker; B.
its lateral halves are flattened out and adhere —“2e._Of queens CG, same
by a sticky liquid excreted upon them by *
glands said to be situated in front of them. . On the relaxation of
the muscle that flattens the empodial lobes the latter spring back
into their original position by the elasticity-of the chitinous band
(gg) in their walls. oa

 

V. THE ABDOMEN, WAX GLANDS, AND STING.

The abdomen of the worker and queen appears to consist of six seg-
ments (figs. 1, 82, 33, 77-VZZ), but it must be remembered that, as
has already been explained, the thoracic division of the body in the
Hymenoptera includes one segment, the propodeum or median seg-
ment, which really belongs to the abdomen and is its true first seg-
ment according to the arrangement in all other insects. Hence,
counting the propodeum (figs. 21 and 32, 7/7) as the first, we find
seven exposed abdominel segments in the worker and queen and
nine in the drone. Each one except the first consists of a tergum
(7) and a sternum (8), the former reaching far down on the side
of the segment, where it carries the spiracle (Sp) and overlaps the
edge of the sternum. The two plates of the last or seventh segment
in the worker and queen are separated by a cleft on each side, and
if they are spread.apart it is seen that the tip of the abdomen
70 THE ANATOMY OF THE HONEY BEE.

incloses a cavity which lodges the sting and its accessory parts. The
end of the abdomen of the male (fig. 56 D) is quite different from
that of the female, while in it parts at least of nine segments are

          
      

Fic, 32.—Lateral view of abdomen of worker, showing the propodeum (Jf) as a part
of the abdomen, of which it is the true first segment.

\ Y

visible, the last is very much modified and is exposed only on the
sides and below.
An internal view of the ventral plates and the lateral parts of the

     

Clip
2 XK
2
2Clsp~
Fic. 33.—Ventral view of abdomen of Fig. 84.—Dorsal view of ab-
worker, showing tip of sting (Stim) and dominal sterna of drone,
palpuslike appendages (StnPlp) pro- showing clasping appendages
jecting from sting chamber within (1Clsp and 2Clsp) of ninth
seventh segment (VIJ). segment.

terga in the worker is shown by figure 20, while a corresponding
view of the male sterna is shown by figure 34. It will be seen that
each sternum is very widely underlapped (viewed from above) by the
THE ABDOMEN, WAX GLANDS, AND STING. 71

one next in front of it and that the intersegmental membrane (J/d)
is reflected from the middle of the dorsal surface of each to the
anterior edge of the following sternum. By removing an individual
plate (fig. 835 A) this is more easily shown. It is also clearly seen
that the transverse line of attachment of the membrane (J/d) divides
the sternum into a posterior part (2d), which is merely a prolonged
reduplication underlapping the following sternum, and into an an-
terior part underlapped by the preceding sternum. The posterior
half is, hence, purely external while the anterior half forms the true
ventral wall of the segment, its dorsal face being internal and its
ventral face external. The anterior part is also very smooth and
shiny and somewhat bilobed and for this reason it is sometimes called
the “ mirrors.” Its edge is bounded by a thickened ridge giving off a
short apodeme (Ap) on each side. The mirrors of the last four
sterna are also, and more appropriately, called the wax plates because
the wax is formed by a layer of cells lying over them. It accumu-
lates on the ventral side in the pocket between the wax plates and the
posterior underlapping prolongation of the preceding sternum. Wax
is formed only on the last four visible segments, i. e., on segments
IV-VII, inclusive.

In studying any part of the body wall of an insect it must always
be borne in mind that the chitin is originally simply an external cutic-
ular layer of a true cellular skin or epidermis (erroneously called
‘“‘hypodermis” in insects), but that in the adult stage the latter
almost everywhere disappears as a distinct epithelium. Thus the
chitin comes to be itself practically the entire body wall, the cell layer
being reduced to a very inconspicuous membrane. However, in cer-
tain places the epithelium may be developed for special purposes.
This is the case with that over the wax plates which forms a thick
layer of cells that secrete the wax and constitute the so-called wax
glands. The wax is first secreted in a liquid condition and is ex-
truded through minute pores in the wax plates of the sterna, harden-
ing on their under surfaces into the little plates of solid wax with
which every bee keeper is acquainted.

The secretion of the wax has been studied by Dreyling (1903), who
made histological sections through the glands at different times in
the life of the bee. He found that in young, freshly emerged workers
the epidermis of the wax plates consists of a simple layer of ordinary
epithelial cells. As*the activities of the bee increase, however, these
cells elongate while clear spaces appear between them and, when the
highest development is reached, the epithelium consists of a thick
layer of very long cells with liquid wax stored in the spaces between
them. In old age most of the cells become small again and in those
bees that live over the winter the epithelium degenerates to a simple
sheet of nucleated plasma showing no cell boundaries. It is thus
evident that the secretion of wax is best performed during the prime
72 THE ANATOMY OF THE HONEY BEE.

of life, which in bees is at about 17 days of age or before, and that
old bees can only gather honey and pollen. Bees do not normally
secrete wax while performing the other more ordinary duties of their
life. When comb is needed a large number of young bees or bees
that have not passed their prime hang together in vertical sheets
or festoons within the hive and are fed an abundance of honey. After
about twenty-four hours they begin to construct comb. During this
time the wax is excreted through the wax plates and accumulates in
the external wax pockets below.
It is poked out of these pockets by
means of the spines on the feet
and is passed forward beneath the
body to the mandibles. By means
of these organs it is manipulated
into little pellets and modeled
into the comb. Dreyling describes
the pores of the wax plates as ex-
cessively fine, vertical, parallel
canals only visible in very thin
sections and under the highest
power of the microscope.
Corresponding abdominal sterna
present quite different shapes in
the three forms of the bee (fig. 35
A, B, and C). In the queen (B)
the sterna are much longer than in
the worker (A), while in the
drone (C) they are shorter and

 

   

Cc have very long lateral apodemes
Fic. 35.—Dorsal surface of sixth abdominal (Ap) .
sternum: A, worker ; B, queen; C, drone; The last three abdominal seg-

showing division of plate by line of at- Si .
tachment of intersegmental membrane ments—the eighth, ninth, and

(Mb) into anterior part with polished tenth—are very different in the

eral suas fn weer tering 2 two sexes on account of thelr

part (Rd) underlapping anterior half of modification in -each to accom-

eee modate the external organs of re-.
production and egg laying. In the female these segments are entirely
concealed within the seventh, but, in the male, parts of both the
eighth and ninth segments are visible externally.

The seventh segment of the drone (counting the propodeum as
the first) is the last normal segment, i. e., the last one having a com-
plete tergum and sternum resembling those of the anterior part of
the abdomen (fig. 56 D, V/J7 and V/JS). Behind the seventh ter-
gum and partly concealed within it is the eighth tergum (V///7)
carrying the last abdominal spiracles (Sp). The eighth sternum is
THE ABDOMEN, WAX GLANDS, AND STING. 73

almost entirely concealed within the seventh. It is very narrow
below, but is expanded at the upper parts of its sides (VJI/S), where
it is partly visible below the eighth tergum and behind the seventh
sternum. The dorsal part of the ninth segment is membranous except
for a small apodeme-bearing plate on each side hidden within the
eighth tergum. The ninth sternum, on the other hand, is a well-
developed semicircular band (JX 8) forming the ventral and ventro-
lateral parts of the ninth segment. It bears on each side two con-
spicuous lobes—one a small, darkly chitinized, dorsal plate (1CJsp)
carrying a large bunch of long hairs, the other a large, thin, ventral
plate (2Clsp). Between these four appendicular lobes is ordinarily a
deep cavity, which is the invaginated penis (fig. 56 E), but in
figure D this organ is shown partly evaginated (Pen). While the
penis is really an external organ, the details of its structure will be
described later in connection with the internal organs of reproduction.
The tenth segment is entirely lacking in segmental form. The anal
opening is situated in a transverse membrane beneath the eighth ter-
gum (VIZIT), and below it is a thin chitinous plate, which may
belong to the tenth segment.

In many insects the modification of the terminal segments of the
males in connection with the function of copulation is much greater
than in the bee. The ninth segment often forms a conspicuous
enlargement called the hypopygium, which is usually provided with
variously developed clasping organs in the form of appendicular
plates and hooks.

The development of the external genital parts of the drone has been
described by both Michaelis (1900) and Zander (1900). A small
depression first appears on the under surface of the ninth segment of
the larva shortly after hatching. Soon two little processes grow
backward from the anterior wall of this pouch and divide each into
two. The part of the larval sternum in front of the pouch becomes
the ninth sternum of the adult, while the two processes on each side
form the upper and lower appendicular lobes (the valva externa and
the valva interna of Zander). The penis at first consists of two little
processes which arise between the valve interne, but is eventually
formed mostly from a deep invagination that grows forward between
them. These four processes arising on the ventral side of the ninth
segment of the male larva are certainly very suggestive of the similar
ones that are formed in the same way on the same segment of the
female and which develop into the second and third gonapophyses
of the sting. If they are the same morphologically we must homol-
ogize the two clasping lobes of the ninth sternum in the male with
the two gonapophyses of this segment in the female. Zander (1900)
argues against such a conclusion on the ground that the genital pouch
is situated near the anterior edge of the segment in the female and
74 THE ANATOMY OF THE HONEY BEE,

posteriorly in the male, while the parts in the two sexes develop
later in an absolutely different manner. These arguments, how-
ever, do not seem very forcible—in the earliest stages the processes
certainly look alike in the two sexes.

The sting of the bee is situated in the sting cavity at the end of the
abdomen, from which it can be quicklyeprotruded when occasion de-
mands. This sting chamber contains also the reduced and modified
sclerites of the eighth, ninth, and tenth abdominal segments. In
fact, the sting chamber is formed by an infolding of these three seg-
ments into the seventh. It is consequently not a part of the true in-
terior of the body or body cavity which contains the viscera, but is
simply a sunken and inclosed part of the exterior, in the same sense
that the oven of a stove is not a part of the real inside of the stove.
Consequently the parts of the sting, though normally hiddert from
view, are really external structures.

A very gentle pull on the tip of the sting is sufficient to remove it
from its chamber, but a sting thus extracted brings along with it the
ninth and tenth segments, most of the eighth segment, the poison
glands, and the terminal part of the alimentary canal. This is due
to the fact that the inclosed segments are attached to the surround-
ing parts by very delicate membranes. For the same reason they so
easily tear from the living bee as the latter hurriedly leaves-its victim
after stinging. The worker thus inflicts a temporary wound and
pain at the cost of its own life. Undoubtedly, however, nature re-
gards the damage to the enemy as of more importance to the bee
community as a whole than the loss of one or a dozen of its members.
The entire stinging apparatus with a bag of poison attached is thus
left sticking in the wound while the muscles, which keep on working
automatically, continue to drive the sting in deeper and deeper and
at the same time pump in more poison. Such a provision certainly
produces much more effective results than would a bee giving a thrust
here and another there with its sting and then rapidly flying away
to escape from danger.

The sting itself, when extracted from its chamber, is seen to con-
sist of a straight tapering shaft with its tip directed posteriorly and
its base swollen into a bulblike enlargement. In superficial appear-
ance the shaft appears to be solid, although we shall presently show
that it is not, but the bulb is clearly hollow and is open below by
a distinct median cleft. Several plates of definite shape and arrange-
ment always remain attached to the sting and overlap its base. The
entire apparatus, including the base of the large poison sac, is shown
somewhat diagrammatically in side view by figure 36. The bulb of
the sting (SAB) is connected with the lateral plates by two arms
which curve outward and upward from its base. (Only the left side
is shown in the figure.) Between these arms the two poison glands
THE ABDOMEN, WAX GLANDS, AND STING. 75

(PsnSc and BGI) open into the anterior end of the bulb. From the
posterior ends of the plates two whitish fingerlike processes (StnPlp)
project backward. When the sting is retracted these lie at the sides
of the shaft (figs. 33 and 37), but in figure 36 the sting is shown in a
partly protracted position. These appendages, often called the sting
palpi, undoubtedly contain s#hse organs of some sort by means of
which the bee can tell when her abdomen is in contact with the object
upon which she desires to use her sting.

A close examination of the sting shows that it is a much more com-
plicated structure than it at first sight appears to be. The shaft, for
example, is not a simple, solid, tapering, spearlike rod, but is a hollow
organ made of «three pieces which surround a central canal. One of
these pieces is dorsal (fig. 36, SAS) and is the true prolongation of
the bulb (SAB), while the other two (Zct) are ventral and slide
lengthwise on tracklike ridges of the dorsal piece. Moreover, each
basal arm of the
sting is double, con-
sisting of a dorsal
or posterior piece
(SAA), which is like-
wise a prolongation
of the bulb, and a
ventral or anterior
piece (Zct), which is
continuous with the
ventral rod of the

shaft on the same Fic. 36.—Semidiagrammatie view of left side of sting of

side. Hence the sting worker, accessory plates (Tri, Ob, Qd), sting palpus
b l . (StnPlp), alkaline poison gland (BGI), and base of large
may be ana yzed into poison sac (PsnSc) of acid gland.

three elements, which
are characterized as follows: The dorsal piece, known as the sheath,
consists of a prominent basal swelling or bulb (SAB) containing a
large cavity, of a terminal tapering shoft (SAS), and of two curved
basal arms (ShA). The ventral part consists of two long slender
rods, called the lancets or darts (Zct), which slide freely upon two
tracks on the ventral edges of the sheath and diverge upon continua-
tions of these tracks along the basal arms of the latter (ShA). The
_ bulb is hollow, containing a large cavity formed by invagination
from below, where it is open to the exterior by a lengthwise cleft.
This cavity continues also through the entire length of the shaft of
the sting as a channel inclosed between the dorsal sheath and the
latero-ventral lancets. This channel, as will be explained later, is
the poison canal of the sting.

Each arm of the sheath (ShA) is supported at its end farthest
from the bulb by an oblong plate (fig. 36, Ob), which normally over-

 
    

StnPlple 56).
: ;
76 THE ANATOMY OF THE HONEY BEE.

laps the side of the bulb, and which carries distally the palpi of the
sting (SinPlp). Each lancet is attached at its base to a triangular
plate (Tri) which lies latero-dorsad to the base of the oblong plate
and articulates with a knob on the dorsal edge of the latter by its
ventral posterior angle. By its dorsal posterior angle the triangular
plate is articulated to a much larger guadrate plate (Qd) which
overlaps the distal half of the oblong plate. A thick membranous
lobe (JX), concave below, where it is thickly set with long hairs,
overlaps the bulb of the sting and is attached on each side to. the
edges of the oblong plates. All of these parts are shown flattened out
in ventral view by
figure 37.

The presence of
the two basal arms
of the sheath might
suggest that this
part is to be re-
garded as made up
of fused lateral
halves. In this case
we should have six
appendicular _ ele-
ments, viz, the two
lancets, the two
halves of the sheath,
and the two pal-
puslike organs. If
now we turn back to
figure 8, showing

 

the component parts
ZB of the ovipositor of
ar a longhorned grass-
Fic, 37.—Ventral view of sting of worker and accessory parts,
flattened out. . uy ' hopper, we can not
py Sree Ces | ee fail to be struck at

once by the great similarity between this organ and the sting of
the bee (fig. 36). The first gonapophyses (/G) of the ovipositor are
identical with the lancets (Zct) of the sting, and their sliding connec-
tion, by means of longitudinal tracks, with the second gonapophyses
(2@) suggests at once that the latter represent the sheath of the
sting (SAS). The identity is still more strongly suggested when we
observe the small bulb (SAB) formed by the fused bases of these
gonapophyses. The third gonapophyses (3G), which inclose between
them the other parts of the ovipositor, represent the palpi of the
sting (SinPlp). If, finally, we study the development of the parts of
the sting we are convinced that this similarity between the sting and
an ovipositor means something more than an accidental resemblance
THE ABDOMEN, WAX GLANDS, AND STING. ar

between two different organs—in fact we can not doubt that the sting
is simply an ovipositor which, being no longer needed for egg-laying
purposes, has been modified into a poison-injecting apparatus. Zan-
der (1899, 1900) and others have shown that the sting of the bee
arises from six little abdominal processes of the larva, two of which
arise on the eighth segment and four on the ninth. Those of the first
pair develop into the lancets, those of the middle pair on the ninth
segment fuse to form the sheath, while those of the outer pair. be-
come the palpi. The ovipositor, it will be remembered, develops in
the lower insects from two pairs of processes arising on the eighth
and ninth abdominal sterna, the second pair of which very soon
splits into four processes. The simultaneous appearance of six on
the bee larva is simply an example of the hurrying process or accelera-
tion that the embryos and young of most higher forms exhibit in
their development.

It is only the higher members of the Hymenoptera, such as the
wasps and the bees and their close relatives, that possess a true sting.
The females of the lower members have ovipositors which closely re-
semble those of such insects as the katydids, crickets, and cicadas, but
which, at the same time, are unquestionably the same as the sting of
the stinging Hymenoptera. It is said that the queen bee makes use
of her sting in placing her eggs in the cells, but both the wasps and
the bees deposit their eggs in cells or cavities that are large enough to
admit the entire abdomen, and so they have but little use for an egg-
placing instrument. But the females of the katydids and related
forms like Conocephalus (fig. 8) use their ovipositors for making a
slit in the bark of a twig and for pushing their eggs into this cavity.
The cicada and the sawfly do the same thing, while the parasitic
Hymenoptera often have extremely long and slender piercing oviposi-
tors for inserting their eggs into the living bodies of other insects.

An examination of the sting in place within the sting chamber, as
shown by figure 41, will suggest what the accessory plates represent in
other less modified insects. It has already been explained that the last
external segment of the female abdomen (fig. 32, VZ/) is the seventh.
Within the dorsal part of the sting chamber is a slight suggestion of
the eighth tergum (fig. 41, V//Z7), which laterally is chitinized as a
conspicuous plate bearing the last or eighth abdominal spiracle (Sp).
The triangular plate (77rd), as Zander has shown by a study of its
development, is a remnant of the eighth sternum, and the fact that it
carries the lancet (Zct) shows that even in the adult this appendage
belongs to the eighth segment. The quadrate plate (Qd), since it is
overlapped by the spiracle plates of the eighth tergum, might appear
to belong to the eighth sternum, but Zander has shown that, by its
development, it is a part of the ninth tergum. In many other adult
Hymenoptera, moreover, the quadrate plates are undoubtedly tergal,
78 THE ANATOMY OF THE HONEY BEE.

for they are sometimes connected by a bridge behind the eighth
tergum. The oblong plate (Ob) and its stalk represent the ninth
sternum, and since it carries both the arm of the sheath (SAA) and
the palpus (Pip) it still maintains its original relationships to the
gonapophyses. The membranous lobe arising from between the
oblong plates and overlapping the bulb of the sting (figs. 36 and 37,
ZXS) must belong to the median part of the ninth sternum.

The tenth segment (fig. 41, X) consists of a short, thick tube having
the anus (An) at its tip. It takes no part in the formation of the
sting, but is entirely inclosed in the dorsal part of the sting chamber
beneath the seventh tergum.

In the accessory plates of the bee’s sting we have a most excellent
illustration of how the parts of a segment may become modified to
meet the requirements of a special function, and also an example
of how nature is ever reluctant to create any new organ, preferring
rather to make over some already existing structure into something
that will serve a new purpose.

There are four glands connected with the sting, two of which
are known to secrete the poison, which is forced through the canal
between the sheath and the lancets and ejected into the wound made
by the latter. It is this poison that causes the pain and inflammation
in the wound from a bee’s sting, which would never result from a
mere puncture. The other two glands have been described as “ lubri-
cating glands,” being supposed to secrete a liquid which keeps the
parts of the sting mechanism free from friction. They lie within
the body cavity, one on each side against the upper.edge of the
quadrate plate, where they are easily seen in an extracted sting, each
being a small oblong or ovate whitish cellular mass. Transverse
microtome sections through this region show that each of these
glands opens into a pouch of the membrane between the quadrate
plate and the spiracle-bearing plate of the eighth tergum. Each
gland cell communicates with this pouch by a delicate individual
duct. The secretion of the glands is thus poured upon the outer sur-
faces of the quadrate plates and might easily run down upon the
bases of the lancets and the arms of the sheath, but, for all that, the
notion that it is lubricative in function is probably entirely conjectural.

The large, conspicuous poison sac (figs. 36, 37, 41, and 57, PsnSc)
that opens by a narrow neck into the anterior end of the bulb of the
sting is well known to everyone at all acquainted with bees. The
poison which it contains comes from the delicate branched thread
attached to its anterior end (fig. 57), a minute tube which, if traced
forward a short distance from the sac, will be seen to divide into two
branches, which are long and much coiled and convoluted, each ter-
minating finally in a small oval enlargement (AG). These terminal
swellings are generally regarded as the true glands and the tubes
THE ABDOMEN, WAX GLANDS, AND STING. 79

(AGID) as their ducts, but the epithelium of the tubes appears to be
of a secretory nature also, and, if it is not, it is hard to see any reason
for their great length. It also does not look
probable that the two little end bodies could B
form all the poison that fills the comparatively
enormous sac.. Nu---

The walls of the poison sac (fig. 38) are lined
by a thick coat of laminated chitin (/n¢) thrown Epth
into numerous high folds. In the neck part of
the sac the folds are arranged very regularly in
a transverse direction and form interrupted
chitinous rings, holding the neck rigidly open.
The epithelium (£pth) contains nuclei (Vz),
but the cell boundaries are very slightly marked. A
There is a distinct basement membrane (BJ/), ric.
forming a tunica propria externally, but there — small piece of wall of

poison sac of sting.
are no muscle fibers of any sort present except
a few which are inserted upon the sac from some of the surrounding
organs and which apparently act as suspensoria.

The poison found in the sac has an
acid reaction and is supposed to consist
principally of formic acid. Hence its
gland is known as the acid gland (AGL)
of the sting.

The other sting gland is a short, very
inconspicuous, and slightly convoluted
whitish tube (figs. 36, 87, 41, and 57,
BG) opening directly into the base of
the bulb ventrad to the opening of the
poison sac. Its walls consist of a thick
epithelium of distinct cells (fig. 39,
Hpth) lined with a thin chitinous in-
tima (/nt) and surrounded by a distinct
basement membrane (BJ/), but, as in
the other gland, there are no muscles
present. The secretion of this gland is
said to be alkaline and the gland is
therefore known as the alkaline gland
(BGl) of the sting.
¢ Experiments made by Carlet (1890)
Fie, 89.—Sections of alkaline gland show that it is only the mixture of the

of sting. A
products from the two poison glands
that is fully effective in stinging properties. Carlet’s experiments were
made upon houseflies and blowflies, He shows (1) that flies stung by a
bee die almost instantly, (2) flies artificially inoculated with the secre-

 

 
80 THE ANATOMY OF THE HONEY BEE.

tion of either gland alone do not die for a long time even in spite of
the necessary mutilation, while (3) successive inoculations of the
same fly first from one gland and then from the other produce death
in a much shorter time than when inoculated from one gland alone—
presumably as soon as the two liquids mix within the body.

The two secretions, one acid and the other alkaline, are poured
together into the base of the sting bulb and mix within the cavity
of the latter. The resulting poison is then driven through the chan-
nel in the shaft to near the tip of the latter, where it makes its exit
into the wound. Since the large poison sac is not muscular, the poison
is not forced through the sting by it, as is often supposed. A glance
at figure 57 (see p. 135) will show that the accessory plates of the sting
support several very compact sets of muscles on their inner faces.
These muscles so act during the process of stinging that the triangular
plates (figs. 36 and 37, 7rz) turn upon their hinge-joint articulations
with the oblong plates (Ob). By this motion of the triangular
plates the attached lancets (Zct) are moved back and forth along
the tracks on the lower ‘edges of the sheath and its arms (SAA).
Each of these tracks consists of a ridge with a constricted base which
dovetails into a correspondingly shaped groove on the dorsal surface
of the lancet. This structure, as seen in cross sections through the
shaft and bulb of the sting, is shown by fig. 40 A, B, and C. The
lancets are thus held firmly in place, while at the same time they may
slide back and forth with perfect freedom. The figures show also
that all three parts of the sting are hollow, each containing a pro-
longation (dc) of the body cavity. Between them, however, is in-
closed another cavity through which the poison flows. This is the
poison canal (PsnC). In the bulb (fig. 40 C) the body cavity is
reduced to a narrow cleft (bc) by the great size of the invaginated
poison canal (PsnC).

It will now be most convenient to describe the apparatus by means
of which the poison is ejected from the sting. As before pointed out,
the large poison sac can have no functions in this connection because
its walls are entirely devoid of muscle fibers. On the other hand,
there is an actual pumping apparatus situated within the bulb. This
consists of two pouchlike lobes, having their concavities directed
posteriorly, attached to the upper edges of the lancets (fig. 40 D and
G, Viv) on the anterior ends of the parts of the latter which slide
within the lower edges of the bulb chamber. The lobes lie side by
side within the bulb (fig. 40 C, Viv), when the lancets are in the same
position,-and each has an accessory lamina against its own inner wall.
When the lancets are pushed backward the walls of the lobes flare
apart against the poison contained in the bulb and drive this liquid
before them into the channel of the shaft, while at the same time they
suck more poison into the front of the bulb from the glands, When,
THE ABDOMEN, WAX GLANDS, AND STING. 81

on the other hand, the lancets are retracted the pouches collapse so
that they may be drawn back through the poison-filled bulb without
resistance, but they are ready for action again as soon as the move-
ment of the lancets is reversed. The whole apparatus thus consti-
tutes an actual force pump in which the lobes on the lancets alter-
nately act as a piston and as valves. The lancets need not work
together; in fact,
they more often
perhaps work al-
ternately, the lobes
being of such a
size as to be ef-
fective either when
acting together or
separately.

The reader ac-
quainted with
other works on
the anatomy of
the bee, such as
those of Cheshire
(1886), Cook
(1904), Cowan
(1904), and Arn-
hart (1906), will
see often repeated

the statement that
the poison leaves Fic. 40.—Details of sting of worker: A, section through tip of
sting showing lancets (Let) and shaft of sheath (SnS) sur-

 

the sting both iby rounding central poison canal (Psn('), and each containing

a ventral opening a prolongation of the body-cavity (bc); B, section of same

5 near base of bulb; C, section of sting through basal bulb,

between the lan- showing poison canal as large invaginated cavity (PsnC)

cets near their tips in bulb of sheath (ShB) containing the two valves (Viv)

of lancets (Let) ; D, part of left lancet carrying valve (Viv),

and by several lat- dorsal view; E, tip of lancet showing pores opening on

eral pores near the bases of barbs (00) coming from body-cavity (bc) of lancet—

not from poison canal; F, dorsal view of shaft of sheath

ends of the lancets showing lateral series of pores (00) from prolongation of

opening from the body-cavity (be); G, lateral view of left valve and part of
lancet.

poison canal upon

the bases of the barbs. The writer, however, has never been able
to observe the exit of the poison from any such lateral pores, while,
on the other hand, it is very easy to watch it exude from between
the lancets on the ventral side of the sting near the tip. If an
excited bee is held beneath a microscope and the tip of the sting
observed, the poison will be seen to accumulate in little drops near
the tip on the ventral side. If, also, the bulb of an extracted sting

22181—No. 18—10-—6
82 THE ANATOMY OF THE HONEY BEE.

be squeezed gently between a pair of forceps the poison will be seen
to emerge in the same way. In fact, it can be actually squirted out
by a sudden compression when the bulb is well filled with poison, but
there is never any evidence of its escape through the sides.

An examination of the end of each lancet does reveal a number of
oblique pores (fig. 40 E, 00) which have been figured by other writ-
ers, and they certainly open on the bases of the barbs as described,
but their inner ends apparently communicate with the body cavity
(oc) of the lancet instead of passing clear through the lancet and
opening into the poison canal. Furthermore, a paired series of
exactly similar pores extends the entire length of the shaft of the
sheath (fig. 40 F, 00), opening on its dorsal surface from the body
cavity (bc). No one could possibly claim that the poison emerges

 

S Tri Ob kk
Fic. 41._Tip of abdomen of worker with left side removed, showing right halves of sev-
enth tergum (VJIT) and sternum (VJJS), containing the sting chamber (kk) cut open
along the line bw, exposing the eighth tergum (VJIIT), the rudimentary tenth segment
(X) carrying the anus (An), and the sting and accessory parts shown by fig. 36.

also through these pores, which, very curiously, do not appear to
have been described before, although they are even more conspicuous
as well as more numerous than those of the lancets. The writer has
not been successful in preparing histological sections of the sting
which show these pores, but they probably constitute the ducts of
some kind of subcuticular glands.

A cross-section through the sting a short distance in front of its
tip shows that the lancets are here separated by a narrow cleft (fig.
40 A), while elsewhere (B and C) they are contiguous. This cleft
between the ends of the lancets forms the exit for the poison from the
channel.

The sting of the queen is much longer than that of the worker
and is more solidly attached within the sting chamber. Its shaft is
THE ABDOMEN, WAX GLANDS, AND STING. 83

strongly decurved beyond the bulb. The lancets have fewer and
smaller barbs than those of the worker, but the two poison glands
are well developed (fig. 57, AGl and BGI), while the poison sac
(PsnSc) is especially large.

A number of minute unicellular glands open upon the interseg-
mental membrane between the seventh and eighth terga of the ab-
domen. These are sometimes called the glands of Nassanoff, after
their discoverer. Nassanoff suggested that they are sweat glands,
while Zoubareff thought that they form small drops of liquid said
to be excreted by bees during flight derived from the excess of water
in the newly collected nectar. Their function, however, has been
much more carefully investigated by Sladen (1902), who found that
they are scent organs producing a strong odor-even when the part
of the back to which they are attached is removed from the rest
of the abdomen. He furthermore identified this smell as the same
that bees give off when a lot of them are shaken from a frame on
the ground close to the front of the hive. Under such circumstances
also, as in natural swarming or during the first flights in the spring
or after a period of bad weather, bees are well known to produce a
peculiar sound called the “joyful hum.” Sladen observed that this
was produced, in the case of bees shaken before the hive, by those
individuals who first found the hive entrance, then by those next to
them, until very soon all the others were informed of the location
of the entrance and proceeded to make their way in. Also, when a
swarm loses sight of its queen, those*that find her first set up this
“joyful hum” and immediately the rest of the swarm is attracted
to the spot. In the springtime the young bees seem to be guided
in their flights by this same hum of the old ones. Sladen, however,
observing the odor emitted at the same time, thinks that this and
not the sound is the real means of information, the sound being
simply incidental to the special movement of the wings produced
for the purpose of blowing the odor away from the body. He argues
that we have no evidence of an acute sense of hearing in bees, while
it is well known that they possess a delicate sense of smell located on
the antenne. This argument certainly seems reasonable, and we
may at least accept Sladen’s theory as the best explanation of the
function of the glands of Nassanoff.
84 THE ANATOMY OF THE HONEY BEE.
VI. THE ALIMENTARY CANAL AND ITS GLANDS.

1. THE GENERAL PHYSIOLOGY OF DIGESTION, ASSIMILATION, AND
EXCRETION.

It is no exaggeration to say that eating is the most important thing
that any animal does and that its alimentary canal is the most im-
portant organ it possesses. The entire system suffers when there is a
deficiency in the food supply or an impairment in the digestive appa-
ratus. Every other function is either subservient to or dependent
upon that which furnishes nourishment to the cells. The senses of
sight, smell, and taste are all more or less concerned in the acquisition
of food. The muscular system enables the animal to hunt for it, to
dig for it, to climb for it, or to chase living prey either on the ground,
in the water, or in the air, and to kill, tear, and chew it when ob-
tained. The blood is the servant of the stomach, for its entire func-
tion in insects is to carry the products of digestion to the body cells.
The heart furnishes the motor power of the blood. The respiratory
function is accessory to that of digestion, inasmuch as it furnishes the
oxygen which unites with the waste materials ejected from the cells
and renders them capable of being removed f the blood. This
removal is accomplished partly by the respiratory system itself and
partly by special excretory organs. Thus we see that the sense organs
and the muscular system are the agents that cooperate in obtaining
the raw food, the digestive tract is the kitchen of the body in which
the food is prepared for use, the blood is the waiter that distributes
it, while the respiratory and excretory systems are the refuse gath-
erers that remove waste products. The nervous system holds the con-
trolling power over all these organs. It regulates them in the per-
formance of their duties and coordinates their actions so that they
all work together. It makes a unified organism out of what would
otherwise be simply a complex mass of variously specialized cells.

The reproductive function alone contributes nothing to the indi-
vidual. In fact, the production of spermatozoa by the male and of
eggs by the female and the nourishing of the embryo and the young
create a demand upon all the other organs for material which is
separated from the individual that produces it. But this is what the
organism exists for; this is its reason for being. At least this is
what it amounts to in the case of the individual, though from a wider
philosophical standpoint the real truth is probably just the reverse,
viz, any species exists because its individuals reproduce themselves.

The writer has already made frequent use of the word “ cell,”
assuming that the reader is familiar with the meaning of this word
as used in anatomy and physiology. The entire body of an animal
or plant is made up of ced/s or their products. The word, however, is
misleading, for a cell is not a small sac or empty space, as was at
THE ALIMENTARY CANAL AND ITS GLANDS. 85

Phy

G AOE MG KREMER Sin . i SEB DS

 

mL

Fig. 42.—Alimentary canal of worker (Phy—Rect), together with pharyngeal glands (1G@1),
and salivary glands of head (2G1) and of thorax (8G1), as seen by cutting body open
from above and pulling the ventriculus (Vent) out to left.
86 THE ANATOMY OF THE HONEY BER.

first supposed from the study of plants, but is a little protoplasmic
body or corpuscle, visible only under the microscope, surrounded by
a membranous cell wall and containing a small internal body called
the nucleus. The different cells of the body are specialized in groups
to do some one particular thing—the salivary cells secrete saliva, the
muscle cells contract, the excretory cells pick out waste substances
from the blood, and sg-on. But this specialization does not signify
that each cell does not perform itsown vital processes in addition to
its specialty. The fact that it remains alive and works means that
the complex chemical components of its body substance or protoplasm
are constantly being reduced to simpler compounds which are ex-
pelled, while new protoplasm is built up: from the supply of food
material brought by the blood. This double process of destruction
and reconstruction is known as metabolism, while its two phases, the
breaking-down process and the building-up process, are known as
katabolism and anabolism,.respectively.

Now, while all the cells of the body must have nourishment, none
of them, except those of the alimentary canal, is capable of utiliz-
ing the raw food materials that an animal obtains in a state of nature.
These materials must therefore be changed into some other form in
order that they may be assimélated by the cells. This change is called
digestion.

The single cell composing the body of a Protozoan, living free in
nature, digests its own food and then assimilates the products of its
own digestion. But, of the cells constituting the body of any mul-
ticellular animal, only those of the alimentary canal are capable of
digesting raw foodstuffs, and, moreover, as digestion is the specialty
of these cells, they have also to digest the food for all the other cells |
of the body. ;

The two most important changes that must be brought about in
the natural food by digestion are those which make it soluble in the
blood and which render it capable of passing through animal tissues.
In the first place, the food must diffuse through the walls of the
alimentary canal as a liquid which mixes with the blood, for there
are no pores or openings of any sort from the alimentary canal into
the body cavity; and in the second place, it must pass through the
walls of the cells themselves. The digestive changes result chiefly in
a breaking down of the complex molecules of the raw food materials
into more simple chemical substances. These are taken up by the
cells and reconstructed into complex protoplasmic molecules which
can not escape through the cell membrane until they are again broken
down into simpler forms.

The waste products of the cells consist principally of carbon, hy-
drogen, and nitrogen. These are converted by the oxygen supplied
by the respiratory system into carbon dioxid, water, and compounds of
THE ALIMENTARY CANAL AND ITS GLANDS. 87

urea. The first, being a gas, mixes with the air in the tracheal tubes
and so reaches the exterior during exhalation. Much of the water is
also given off through the tracheal system in the form of vapor which
exhales from the spiracles, but, since insects are covered by their
hard chitinous shell, it is probable that they do not “sweat.” The
compounds of urea, and probably also some water, are separated
from the blood by the excretory glands, called Malpighian tubules
in insects, which empty their products back into the alimentary
canal, whence they are discharged with the feces from the intestine.

Digestion is brought about by substances called enzymes which are
contained in the various liquids mixed with the food in the alimentary
canal. These liquids are secreted by the salivary glands and by the
cellular walls of the stomach.

2. THE SALIVARY GLANDS.

The opening of the salivary duct on the base of the proboscis has
already been described (see pp. 49-51). The true salivary glands, or
those corresponding with the salivary glands of other insects, are
arranged in two pairs, one situated within the head (figs. 19 and 42,
2@1) and the other within the thorax (fig. 42, 3@7). The four ducts
unite into one median tube, which enters the base of the labium (fig.
19, SalD) and opens upon the upper surface of the ligula (fig. 15 F,
and fig. 16, SalDO). The large and conspicuous glands lying within
the anterior and upper parts of the head and opening into the
pharynx will be described later in connection with this organ. They
are special pharyngeal glands in no way homologous with the salivary
glands of other insects, and are by many supposed to secrete the
brood food instead of a digestive liquid like saliva.

The salivary glands of the head (System No. 2 of Cheshire, post-
cerebral glands of Bordas) lie against the posterior walls of the
cranium. In the worker each consists of a loosely arranged mass of
pear-shaped follicles or acini whose individual ducts unite irregu-
larly with one another and eventually form a common duct on each
side (figs. 19, 42, and 43 F, 2G7). Their two ducts unite with the
median duct from the thoracic glands just before the bases of the
mesocephalic pillars (fig. 19). In the drone these glands have a
quite different appearance from those of the female, each consisting
of a compact mass of very small follicles connected by minute ducts
and flattened against the posterior walls of the head (fig. 43 B and C,
2Gl). A large lobe of this gland in the drone extends forward on
each side against the face, between the compound eye and the clypeus
(fig. 10 C, 2G), thus occupying the position of the large mandibular
gland in the worker (A, /J/dG@/) and in the queen (B, 1MdG1).
There is also a prominent triangular mass of glandular cells in the
drone situated just above the ocelli (fig. 10 C, 2G72) which has been
88 THE ANATOMY OF THE HONEY BEE.

described. by Bordas (1895) as a separate gland opening by two ducts
into the cesophagus just behind the pharynx. The writer, however,
has been utterly unable to discover any such ducts, though two sus-
pensorial ligaments of the anterior end of the cesophagus are at-
tached to the wall of the head at the posterior ends of these glands
(fig. 11 B, g) and might easily be mistaken for ducts. These “ post-
ocellar glands” of Bordas, moreover, appear to be simply detached
lobes of the postcerebral glands. They are prominent also in the
queen (fig. 10 B, 2G@7) and are represented by a few follicles in the
worker.

 

Fic. 43.—A, small piece of large lateral pharyngeal glands in head of worker; B, piece of
postcerebral salivary glands in head of drone; C, postcerebral glands (2G1) in normal
position against posterior wall of head in drone; D, pharyngeal plate (s) of worker,
ventral view, showing bases of lateral pharyngeal glands (7G) and their receptacula
(mm), and median ventral pharyngeal gland (4Gl) ; E, corresponding view of pharyngeal
plate of drone, showing entire absence of lateral pharyngeal glands, and greater devel-
opment of small median glands (4G1) ; F, part of postcerebral gland of worker.

Bordas describes the follicles of the postcerebral glands in the
worker as hollow sacs, each having a large lumen lined with a chiti-
nous intima. Their secretion, he says, is a thin viscid liquid, pale
yellow in color and having a slightly alkaline reaction. According to
Schiemenz (1883) each gland is developed as an outgrowth from the
common duct of the thoracic glands.

The salivary glands of the thorax in the bee (System No. 3 of
Cheshire, thoracic salivary glands of Bordas) are the ones that cor-
respond with the ordinary salivary glands of other insects. They
are described by Schiemenz (1883) as being formed inside of the
THE ALIMENTARY CANAL AND ITS GLANDS. 89

outer covering (tunica propria) of the first part of the larval silk
glands. But it is of common occurrence in insects that the salivary
glands are temporarily specialized as silk-producing organs in the
larva. In the adult worker these glands lie in the ventral part of
the anterior half of the thorax (fig. 42, 3Gl). The two are widely
separated anteriorly, but their posterior ends are contiguous. Each
consists of a mass of small, many-branched, glandular tubes opening
into several collecting ducts which empty into a sac near the ante-
rior end of the gland (21). From each of these reservoirs, then, a duct
(Det) runs forward and fuses with the one from the opposite side
just within the foramen magnum of the head. The common duct
thus formed turns downward within the head, receiving the two ducts
of the postcerebral salivary glands and then enters the base of the
mentum (figs. 19 and 48 C, SalD), to open as already described on the
upper side of the ligula at the root of the glossa and between the
bases of the two paraglosse (fig. 15 F and 16, SalDO). The
secretion of the thoracic glands is said also to be weakly alkaline.
Therefore the entire salivary fluid poured out upon the labium is
alkaline, and it must be designed to act especially upon the food
taken through the proboscis. This action, furthermore, on account of
the location of the salivary opening, may take place before the food
enters the mouth.

The food of the bee consists normally of pollen, nectar, and honey.
The first is eaten entirely with the mandibles, while the other two are
taken through the proboscis. The pollen is to the diet of the bee what
meat is to ours; that is to say, it contains the proteid or nitrogen-
containing ingredient of the food which is necessary to the sup-
port of any animal, and also substances comparable with fat, called
in general hydrocarbons. The nectar and honey consist principally
of grape sugar, fruit sugar, and carie sugar, which belong to the class
of chemical substances known as carbohydrates. Now, all of these
foodstuffs, except the grape and fruit sugars, have to be changed
chemically by the digestive process before they can be absorbed into
the blood. The pollen, which contains the proteids and hydrocarbons
of the food, is taken directly into the mouth by means of the man-
dibles and apparently is not digested until it reaches the small in-
testine, and therefore it would seem that it is the cane sugar which
must be affected by the saliva. The change, or inversion, as it is
called, of cane sugar, which has a very large molecule (C,,H,,0,,),
consists of its reduction to grape and fruit sugars which have smaller
molecules (C,H,,0,). Starch (C,H,,O,) must also be reduced to
simpler and more soluble compounds before it is capable of absorp-
tion. Its inversion is effected in us partly by the saliva, but starch
appears to form a very inconsiderable element in the bee’s diet.
90 THE ANATOMY OF THE HONEY BEE.

3. THE ALIMENTARY CANAL.

The alimentary canal is a tube which extends through the entire
length of the body and, on account of being more or less coiled, it is
generally considerably longer than the length of the body in insects.
It has no openings of any sort into the body cavity. The internal
organs are packed closely about it, and the interstices are filled with
the blood, there being no special arteries or veins in insects. The
amount of space occupied by the alimentary canal varies according to
the amount of food it contains, and for this reason it seldom looks
exactly alike in any two individuals examined.

The part of the canal immediately following the mouth forms an
enlargement (fig. 42, Phy) called the pharynw. Succeeding this is
a slender tube which leaves the head by the foramen magnum above
the small transverse tentorial bar and traverses the entire length
of the thorax. This is the esophagus (@). In the-anterior part of
the abdomen the cesophagus expands into a large thin-walled sac
which is ordinarily called the crop or ingluvies, but which, in the
bee, is known as the honey stomach (7S). Behind this is a short,
narrow, necklike division, with rigid walls constituting the pro-
ventriculus (Pvent). Then comes a large U-shaped part, with thick,
spongy-looking walls containing numerous annular constrictions.
This is the ventriculus (Vent), or stomach, of the bee, frequently re-
ferred to as the “chyle stomach.” Following the ventriculus is a °
short, narrow, coiled small intestine (SInt) having a circle of about
one hundred long, greatly coiled, blind, threadlike tubes opening into
its anterior end. These latter are called the Malpighian tubules
(Mal). Functionally they do not belong to the digestive tract, since
they are excretory organs, corresponding with the nephridia of other
invertebrates and with the kidneys of vertebrates. Following the
small intestine is the large intestine, or rectum (Rect), which is often
distended by its contents into a great sac occupying a large part of
the abdominal cavity. Six whitish bands on its anterior end are
called the rectal glands (RG). The rectum opens to the exterior
through the anus, which is situated, as already described, at the end of
the rudimentary tenth or last segment of the abdomen (fig. 41, An).

After this brief general survey of the parts of the alimentary
canal, we shall proceed with the description of each in detail, and at
the same time give what is known of the réle each plays in the
process of digestion. What is known, however, about digestion in
the bee, or in any insect, for that matter, really amounts to nothing,
but the views of various writers on the subject must be discussed
briefly, in order to show how little has actually been demonstrated.

The pharynx (figs. 11 B, 19, and 42, Phy) lies in the anterior part
of the head close behind the clypeus, extending from the mouth
THE ALIMENTARY CANAL AND ITS GLANDS. 91

dorsally to above the antenne, where it turns posteriorly and con-
tracts into the much narrower esophagus (@). Attached to its
walls are numerous suspensorial muscles, whose contractién must
expand the pharyngeal cavity, while the latter may be contracted
by the sheet of muscles surrounding its walls. In this way the
pharynx is undoubtedly able to perform a sucking action, by means
of which the liquid foods are taken into the mouth. Its lateral
walls are strengthened by two long, chitinous rods (figs. 11 B and
19, h), which arise from a median anterior plate in its floor (fig. 19,s).
The anterior end of this plate is prolonged into two free, tapering
lobes which hang down over the lower rim of the mouth. The plate,
in the worker, and the bases of the rods are shown in ventral view,
removed from the pharyngeal wall, in figure 43 D. Near where the
rods join the plate are two long, chitinous pockets (mm), opening
above, which receive the ducts of the two large glands (/@/) lying
within the anterior part of the head. Between these two pockets is a
transverse row of cells (4G7), which have been described by Bordas
(1895) as the “sublingual glands,” but this name is not appropriate
in insects, for, while the gland in question may be suggestive of the
sublingual salivary gland of vertebrates, it does not lie beneath the
tongue or lingua of the bee. Although the pharyngeal plate lies
upon the floor of the true mouth, it is not, as already explained (p.
44), the equivalent of what is properly called the tongue, lingua, or
hypopharynx in other insects—this organ being absent in most
Hymenoptera. The only suggestion the writer can make, however,
is to call this group of cells the ventral or median ventral pharyngeal
gland in distinction to the large lateral glands. A comparative view
of the pharyngeal plate and its accessory parts in the drone is given
in figure 43 E. The plate itself (s) is shorter than in the worker,
and its anterior lobes are smaller. The lateral glands and their
receptacula are entirely absent, but the median glands (4@/)_.are
much larger than those of the worker, Bordas says that each acinus
of the latter glands in both the worker and the drone is provided
with a fine, sinuous canaliculus, and that these tiny ducts open
separately in two bundles on the lateral parts of the pharyngeal
plate. The lateral glands are present in the queen, but are very small
and rudimentary.

Especial interest attaches to the large lateral pharyngeal glands of
the worker (System No. 1 of Cheshire, the supracerebral glands
of Bordas), because they are regarded by many as the source of the
brood food and the so-called “ royal jelly,” which is fed to the larve
and to the adult queens and drones by the workers. Each consists
of a long coiled string of small ovate follicles attached to one median
duct (fig. 48 A) and the two are intricately packed into the anterior
and upper parts of the head (figs, 10 A, 19, and 42, 1G). Each
92 THE ANATOMY OF THE HONEY BEE.

acinus consists of a solid mass of several small cells, which are pene-
trated by a large number of fine, chitinous ducts, arising in the neck
of the acinus from the common duct of the gland. These follicular
ducts can be very clearly shown by treating a part of the gland with
weak caustic potash, which dissolves the protoplasm of the cells
and brings out the bunch of ductules very clearly.

The fact that these glands are entirely absent in the drone and at
best rudimentary in the queen shows that they must in some way be
connected with the special functions of the worker. Schiemenz (1883)
and Cheshire (1886) have shown that their development in the dif-
ferent species of bees is in proportion to the social specialization.
They vary from a group of cells opening by separate ducts upon the
pharyngeal plate to the highly developed condition they present in
the honey bee. The writer questions, however, whether these authors
did not mistake the median pharyngeal glands of these lower genera
of bees for rudimentary representatives of the lateral glands. Bordas
states that the former occur in all Hymenoptera, but Schiemenz and
Cheshire did not seem to recognize them. The bumblebees (Bombus)
have them almost as well developed as the honey bee (Apis), espe-
cially the large females. In the genus Psythirus they are similar to
those of Bombus but are smaller, while in such genera as Andrena
and Anthophora they are rudimentary or consist of a few scattered
cells. Both Schiemenz and Cheshire have thus argued strongly that
these glands of the pharynx are the organs that produce the brood
food. On the other hand, Schénfeld (1886) has made an equally
strong plea in favor of the ventriculus as the producer of this impor-
tant material. He believes that the brood food, especially royal
jelly, is regurgitated chyle. Both Schénfeld and Cook (1904) fed
bees in a hive some honey containing powdered charcoal and later
found this in the brood food in the comb cells, thus apparently con-
firming its ventricular origin. However, the charcoal that got into
the cells might have come from the mouth, the cesophagus, or the
honey stomach. It, of course, could not have gone through the
stomach walls and entered the pharyngeal glands, as proved by Dr.
J. A. Nelson, of this Bureau, from microtome sections of bees fed on
lampblack. The arguments, then, in favor of the stomach and the
pharyngeal glands seem equally strong, and perhaps the truth is, as
occurs in so many such cases, that both sides are right—that the brood
food is a mixture of chyle from the stomach and of secretion from
the pharyngeal glands.

Arnhart (1906) seems to adopt the position that the brood food
is chyle which has been acidified by the addition of an acid from the
glands. He states that the acid reaction of the royal jelly is due to
the presence of three-fourths of 1 per cent of tartaric acid. The
contents of the ventriculus, on the other hand, and for that matter
THE ALIMENTARY CANAL AND ITS GLANDS. 93

of all the parts of the alimentary canal, are alkaline. Hence, it
seems very logical to suppose that if the brood food comes from the
stomach, its acid constituent is furnished by the glands in the head.
But the difference between the brood food found in the cells and the
contents of the ventriculus is so great that it would seem as if a very
substantial addition of something more than a mere preservative acid
must be made to the latter.

The brood food given to the queen larve, known as royal jelly, is a
gummy paste of a milky-white color when fresh, but when taken out
of the cell it soon acquires a darker tone with a yellowish tint. Under
the microscope it appears to be a homogeneous, very minutely granu-
lar mass. It is very acrid and pungent to the taste, and must be
strongly acid. Samples examined by the writer taken from cells
containing queen larve two and four days old contained a number of
fresh undigested pollen grains but no bits of hairs such as occur in
the stomach.

The possible ventricular origin of a part of the brood food and its
regurgitation will be further discussed when we treat of the stomach

(page 98). The writer does not advocate any personal view regard-
ing the origin of this larval food—the fact is, there is not enough
known about it to enable one to formulate any opinion worth while.
We know only that the whitish paste comes out of the mouths of the
workers, but we know nothing of where it is made or of how it is
made. Hence we can but await the evidence of further investigation.

The brood food is fed to the larve by the workers and is produced
im greatest abundance by the younger individuals. The larve of the
queens are said to receive nothing but pure royal jelly throughout
their entire developmental period, while the larve of the drones and
the workers are given the pure product only during the first three
days of their life. From the beginning of the fourth day on, honey
is said to be mixed with the diet of the drones and workers and, in
the case of the former, undigested pollen also. Moreover, the adult
queens and the drones receive a certain amount of prepared food
throughout their lives; if they do not get it they become weak. While
they can feed themselves with honey they apparently can not eat
pollen, and consequently are not able to obtain the proteid element of
diet unless fed this in a predigested condition by the workers. Dur-
ing egg-laying activity the queen especially demands this food, and
by furnishing or withholding it the workers probably have the power
of stimulating or inhibiting her production of eggs. Arnhart (1906)
says that the workers feed it to weak or starved members of their own
class, the material being accumulated upon the upper surface of the
mentum of one bee whence it is sucked up through the proboscis by
the other. All of these statements, however, concerning the feeding
of the brood and the differences in the diet need to be verified. They
94 THE ANATOMY OF THE HONEY BEE.

are based chiefly on the work of Planta, published in 1888. Cheshire
(1886) states that the stomachs of queens contain a substance which
is “ microscopically indistinguishable from the so-called royal jelly,”
scarcely a pollen grain being discoverable in it. If this is so, it would
. seem to prove that the queen is fed this substance by the worker, for
the stomach of the latter is invariably filled with a dark-brown slime
containing a vary-
ing amount of pol-
len and in no way
resembling royal
‘jelly. Cheshire
further says that
before impregna-
tion the stomachs
of the queens al-
ways contain pol-
len, the royal jelly
being found in
them two or three
days after impreg-
nation, when all
traces of pollen
have disappeared.
The narrow
esophagus (fig. 42,
@’)isa simple tube
with a thick chiti-
nous lining and

 

 

i
ay muscular walls.
Mm The epithelium (fig.
2y 45) is very rudi-

uf

s mentary, its cell
Dé boundaries being

Fic. 44.—A, honey stomach (HS) of worker with posterior end lost and its nuclei
of esophagus (G?), proventriculus (Pvent), and anterior :
end of ventriculus (Vent); B, same of queen; C, honey (Wu) appearing as
stomach (HS) of worker mostly cut away exposing the if imbedded in the
stomach-mouth (nn) of proventriculus (Pvent) leading into
ventriculus (Vent) ; D, honey stomach of drone. lower layers of the
thick transparent

intima (/nt). The muscles are disposed in an outer layer of trans-
verse fibers (7Mcl) and an inner layer of longitudinal ones (Zdfcl).

The honey stomach (fig. 42, ZS) is simply an enlargement of the
posterior end of the csophagus lying within the anterior part of
the abdominal cavity. It is best developed in the worker (fig. 44 A),
but is present also in the queen (B) and in the drone (D). The
organ should perhaps have been named the nectar stomach, for its

Hh
'
THE ALIMENTARY CANAL AND ITS GLANDS. 95

principal function in the bee is to hold the nectar as it is collected
from the flowers and to allow the worker to accumulate a consider-
able quantity of this liquid before going back to the hive. Hence,
since the honey stomach is a sac with very distensible walls, its
apparent size varies greatly. When empty it is a small flabby pouch,
but when full it is an enormous balloon-shaped bag with thin tense
walls. The histological structure of the honey stomach (fig. 45, ZS)
is exactly the same as that of the esophagus. The numerous high
folds into which its epithelium (pth) is thrown permit the enor-
mous expansion of which the sac is capable. When a worker with
its honey stomach filled with nectar reaches the hive, the nectar is
either stored directly in a cell or is given up first to some other
worker, who places it in a cell.

It would appear that all the food swallowed by a bee must go first
into the honey stomach, and since the bee’s diet consists of pollen and
honey as well as nectar, one would suppose that in regurgitating the
latter the bee would also disgorge the pollen it might have recently
eaten. Honey which is made from the regurgitated nectar does
indeed contain some pollen, but most of the pollen eaten by the bee
is undoubtedly retained in the stomach as food. The apparatus by
means of which the pollen is supposed to be separated from the nec-
tar belongs to the following division of the alimentary canal, but it
is not known that the worker takes nectar, and pollen for food, into
its honey stomach at the same time.

The proventriculus (figs. 42 and 44, Pvent) forms the necklike stalk
between the honey stomach (48) and the true stomach or ventricu-
lus (Vent), but a very important part of it also projects up into the
honey stomach (fig. 44 C). If the honey stomach be slit open, a
short, thick, cylindrical object will be seen invaginated into its pos-
terior end and having an X-shaped opening at its summit (fig. 44 C,
nn). This opening is the mouth of the proventriculus, and its four
triangular lips, which are thick and strong, mark four longitudinal
ridges of the proventricular tube. This structure is commonly known
as the “stomach-mouth” and is supposed to be an apparatus de-
signed especially to enable the worker to pick out pollen grains from
the honey stomach and swallow them on down into the true stomach
or ventriculus, while the nectar is left to be stored in the hive.
Cheshire says: “While the little gatherer is flying from flower to

-flower her stomach-mouth is busy separating pollen from nectar.”
This notion is so prevalent among bee writers in general that it
passes for a known truth. Yet it has really never been shown that
the worker eats pollen while she is gathering nectar. Probably no
more pollen is ever mixed with the nectar in the honey stomach than
is found in the honey itself. Furthermore, under normal conditions
pollen never accumulates in the honey stomach, even when the bee
96 THE ANATOMY OF THE HONEY BEE.

is not collecting nectar—or, at least, the writer has not observed it—-
while, finally, both the proventriculus and its mouth are just as well
developed in the queens and drones as in the workers, though neither
of the former are known to eat pollen, and they certainly do not
gather nectar.

If the honey stomach be cut open in a freshly killed bee, the
proventricular mouth may be seen still in action.. The four lips
spasmodically open wide apart with a quivering motion and then
tightly roll together and sink into the end of the proventricular
lumen. This, of course, suggests their picking pollen out of the
nectar, but it is probably simply the ordinary process by means of
which the proventriculus passes any of the food in the honey stomach
on to the ventriculus. Nearly all insects have some such proventricu-
lar apparatus, which simply takes the stored food from the crop as
it is needed by the stomach. In some insects it forms apparently a
straining apparatus, which prevents coarse, indigestible fragments
from entering the stomach, while in some the proventriculus may be
a triturating organ comparable with a bird’s gizzard. Bees, how-
ever, do not crush the pollen either in their mandibles or in the
proventriculus, for it occurs in perfect condition in the ventriculus.

Hence, before the current notion that the “ stomach-mouth ” is
for the special purpose of taking pollen out of the nectar in the
honey stomach can be accepted it must be first demonstrated that
the workers eat pollen while the honey stomach contains nectar to
be stored in the cells, i. e., any more than is disgorged along with
the nectar; and, secondly, a reason must be shown why the queens
and drones should have a ‘“stomach-mouth ” as well developed as
that of the worker. In the meantime it appears most logical to
regard the proventricular mouth as simply the ordinary apparatus,
“possessed by insects in general, by means of which all of the food is
passed from the crop to the stomach.

A longitudinal section through the honey stomach, the proventric-
ulus, and the anterior end of the ventriculus is shown in figure 45,
which is made from a queen. The proventriculus does not differ from
that of a worker, but the honey stomach is smaller and not so much
turned to one side (cf. fig. 44 A and B). The two muscle layers of
the cesophagus continue down over the walls of the honey stomach
(TMecl and Licl). The outer layer of transverse fibers, however,
ceases at the posterior end of this organ, while the longitudinal fibers
continue posteriorly over the proventriculus and the ventriculus as
an external layer (Zdfcl). A new layer of internal transverse fibers
begins on the proventricular walls and extends backward on the
ventriculus (7Mcl) beneath the longitudinals. Hence the muscles
on the esophagus and crop are in reverse order from those of the
proventriculus and ventriculus. The proventriculus is deeply in-
THE ALIMENTARY CANAL AND ITS GLANDS. 97

vaginated into the posterior end of the honey stomach. Each lobe
of its mouth forms a thick triangular ridge on the walls of its
lumen, in which lies a special mass of longitudinal muscle fibers
(LMcl). The epithelium of the lumen is lined by a thick, smooth,
chitinous intima (Jnt), while the lobes of the mouth (nn) are pro-
vided with bristles point-
ing inward and backward
into the mouth opening.
The posterior opening
of the proventriculus into
the ventriculus is guarded
by a long tubular fold
of its epithelium (fig. 45,
PventVlv), the proventric-
ular valve. This would
appear to constitute an
effective check against the
escape of any food back
into the proventriculus, It
looks like one of those traps
which induces an animal to
enter by a tapering funnel
but whose exit is so small
that the captive can not
find it from the other side.
Yet Schonfeld has elab-
orately described experi-
ments by means of which
he induced the ventriculus
to discharge its contents
through the proventriculus
into the honey stomach and SFI) “Fe
even into the end of the Le PlemViy Ve
cesophagus. He says that pe
he did this by gently tap- th Pp
ping on the honey stomach pre. 45.—Longitudinal median section of base of
and the ventriculus at the cesophagus (G),honey stomach (HS), proventricu-

sametime. The experiment lus (Pvent) and ventriculus (Vent) of a queen.

was repeated many times with unvarying results and Schénfeld de-
scribes so minutely what happened that we can not disbelieve his
statements. From these experiments he argues that the larval food-
stuff is prepared in the stomach and regurgitated through the proven-
triculus directly into the cesophagus by a contraction of the honey
stomach which brings the stomach-mouth against the base of the esoph-

22181—No. 18—10——7

 
98 THE ANATOMY OF THE HONEY BEE.

agus. We shall have to postpone a further discussion of this subject
to page 99, after the ventriculus and its contents have been described.

The ventriculus (fig. 42, Vent) is the largest part of the alimentary
canal in the bee and is bent into a U-shaped loop of which the pos-
terior arm is dorsal. It is cylindrical and does not vary so much in
shape and diameter according to its contents as do the other parts of
the canal, although the numerous transverse constrictions which give
it a segmented appearance are not at all constant. When examined
under alcohol the ventriculus has an opaque whitish appearance, but
in the natural condition—that is, as seen when examined in a freshly
killed or asphyxiated bee—it is of a dark-brown color with lighter
rings corresponding to the constrictions. The latter represent in-
ternal folds where the walls are really thicker than elsewhere, the
color being due to the contents which naturally show more plainly
through the thin parts.

The contents of the ventriculus invariably consist of a dark brown
mucilaginous slime and generally also of a varying amount of pollen.
The latter is most abundant in the posterior arm of the ventricular:
loop and is often densely packed in its rear extremity, while the an-
terior arm may be almost entirely free from it. The pollen in the
ventriculus is always fresh-looking, the native color showing dis-
tinctly through the enveloping slime while most of the grains yet re-
tain all of their contents. The writer has examined many samples
of pollen from the stomachs of workers and, in all, the great mass of
it showed no evidence of digestion, the color being fresh and the
contents perfect—only a few had the latter shrunken and seldom was
an empty shell observed. On the other hand, the pollen contained
in the small intestine has invariably lost its bright color, the contents
of the majority of the grains are more or less shrunken, while a num-
ber of empty shells are to be found. That in the rectum, finally, con-
sists in large part of empty shells or of grains having the contents
greatly shrunken and apparently mostly dissolved out, although a
few perfect and bright-colored.grains are always present, looking as
if entirely unaffected by the digestive liquids. From these observa-
tions the writer would conclude that the digestion of pollen takes
place principally in the intestine. In all parts of the alimentary
tract there occur numerous bits of feathered bee-hairs, but these seem
to be especially numerous in the ventriculus.

We are now in a position to discuss the possibility of the production
of the brood food in the stomach. Schénfeld (1886), as has already
been stated, argues that this substance is regurgitated “chyle” from
the ventriculus. Arnhart (1906) adopts this view and elaborates
considerably upon the chemical process by means of which the trans-
formation of “chyle” into this larval food is effected through the
addition of tartaric acid from the pharyngeal glands of the head.
THE ALIMENTARY CANAL AND ITS GLANDS. 99

The ventricular contents do become slightly milky when treated with
a solution of tartaric acid, but they are not changed into anything
at all resembling royal jelly. Moreover, a transformation of the
brown slimy contents of the ventriculus into the white gummy paste
on which the larve are fed does not seem possible without the addi-
tion of much other material. In fact the added material must make
up the conspicuous part of the larval foodstuff and, from a purely
argumentative standpoint, it would not seem necessary to assume that
it contains any “chyle” at all. Again, if it were not for Schénfeld’s
experiments one could not easily believe that the food could be dis-
gorged through the proventricular valve. The conspicuous action of
the proventricular mouth is a swallowing motion, and the writer has
not been able to induce the ventriculus to disgorge its contents
through it in the way that Schénfeld describes, although perhaps
sufficient care was not observed in exposing the organs. Cheshire
states that.the proventricular tube (fig. 45, PventV7v) in the ventricu-
lus ‘rather makes regurgitation improbable than impossible,” while
he argues that the down-pointing bristles of the stomach-mouth would
further interfere with this process. Cowan adopts the view of
Dufour and Schénfeld that the brood food is of ventricular origin,
and says in this connection: “Although saliva from the glands
(especially System I) is probably added to the food, this can not,
from its great variability, be entirely a secretion, as stated by
Schiemenz. The work of Doctor Planta, we think, conclusively proves
that the food is not a secretion, and that the nurses have the power
of altering its constituents as may be required for the different bees.”
If the variation of the food is under the control of the workers pro-
ducing it, it does indeed look impossible that it should be produced
entirely by glands. Cowan illustrates by a diagram how regurgita-
tion through the proventriculus may be possible in spite of the pro-
ventricular tube projecting into the ventriculus. Since this tube is
simply a cylindrical fold its walls, as shown in figure 45, PventVlv,
consist of two layers, and Cowan says that “ when the bee wishes to
drive the chyle food from the chyle-stomach (Vent) into the cells
it forces the stomach-mouth (nn) up to the esophagus (@) and the
prolongation (PventVlv) unfolds, extending the chyle-stomach to the
cesophagus, making a direct communication through which the food
is forced by compression of the chyle-stomach by its muscles.” The
‘honey-stomach of the worker is much larger than that of the queen,
shown by figure 45, in which there is not enough space for the unfold-
ing of the proventricular tube. This mechanism suggested by Cowan
looks simple and conclusive in a diagram, but when one attempts to
unfold the proventricular tube by grasping the stomach-mouth in a
pair of fine forceps and pulling the top of the proventriculus upward
it is found that, while the tube can be entirely straightened out, doing
100 THE ANATOMY OF THE HONEY BEE.

so involves the tearing of all the fine muscle fibers and tracheal
branches uniting the honey-stomach to the upper end of the ventricu-
lus (fig. 45). If, then, the organ itself can not be made to work
according to this scheme, it might be supposed that the inner wall of
the proventriculus andthe tube are evaginated through the stomach-
mouth (nn), but the walls of the former certainly appear to be en-
tirely too rigid to permit of any such performance as this. Finally,
it is not clear how any eversion of the tube could be produced by the
proventricular muscles as they exist.

The various facts and arguments bearing on the origin of the
hrood food may be summarized as follows:

1. The brood food itself is a milky-white, finely granular, and
gummy paste having a strong acid reaction said to be due to the
presence of tartaric acid.

2. The pharyngeal glands of the head are developed in proportion
to the social specialization of the various species of bees; they are
always largest in those individuals that feed the brood, and they
reach their highest development in the workers of the honey bee.
Front this it would seem that they are accessory to some special
function of the worker.

8. The contents of the stomach in the workers consist of a dark
brown, slimy, or mucilaginous substance in no way resembling the
brood food, even when acidulated with tartaric acid. Pollen is
present in varying quantity, mostly in the posterior end of the
stomach, and shows little or no evidence of digestion. Since the
brood food is highly nutritious, it must contain an abundance of
nitrogenous food material which is derived only from pollen in the
‘bee’s diet. Therefore it is not clear how the stomach contents can
alone form brood food.

4. The constituents of the food given to the different larvae, at
different stages in their growth, and to the adult queens and drones
show a constant variation apparently regulated by the workers pro-
ducing it. A variation of this sort can not be explained if it is
assumed that the brood food is produced by the glands alone.

5. Powdered charcoal fed to a hive of bees appears after a short
time in the brood food in the cells, and this has been urged as proof
that the latter is regurgitated “chyle.” But it is certainly entirely
possible that the charcoal found in the food might have come only
from the honey stomach or even from the cesophagus or mouth.

6. We have Schénfeld’s word for the statement that a regurgita-
tion of the stomach contents may be artificially induced by irritation
of the honey stomach and ventriculus in a freshly dissected bee, but
all explanations offered to show: how this is mechanically possible
in spite of the proventricular valve are unsatisfactory when the
actual anatomical structure is taken into consideration.
THE ALIMENTARY CANAL AND ITS GLANDS. 101

The only conclusion, then, that we are really warranted in draw-
ing concerning the origin of the royal jelly or of any of the larval
food paste is that we do not know anything about it. Cheshire is
probably responsible for the widespread opinion that it is formed
by the pharyngeal glands, though Schiemenz (1883) published a
large paper containing this theory three years before Cheshire’s
book was printed. The “chyle” theory, which also has many advo-
cates, originated with Dufour but was principally elaborated by
Schénfeld. Arnhart would derive the brood food from both the
stomach and the glands. But we are still absolutely in the dark,
since we lack definite and conclusive information. A satisfactory
study of the subject would involve the chemical investigation of
very minute quantities of substances, and it may be a long time before
any interested person is found capable of undertaking a work of this
sort. The writer of the present paper is professedly preparing an
account only of the structure of the organs, but is doing this with
the hope that it may furnish a basis for some future investigator who
shall have time to devote himself to a study of the chemistry and
physiology of the digestive organs and their glands.

In vertebrate animals the digestive secretion of the stomach is acid
and its enzymes bring about especially the digestion of proteids. The
resulting acid mixture is called chyme. In the intestine the contents
are flooded with various alkaline liquids whose enzymes then take up
the digestion of the other food elements. The final prepared product,
which is absorbed by the lacteals, is called chyle. These names have
been applied to the contents of the alimentary canal in insects—espe-
cially by Arnhart (1906), who speaks of the material undergoing
digestion as “chyme” and the completed products as “chyle.” But
absolutely nothing is known of the digestive process in insects beyond
the fact established by Plateau (1874) that the contents of all parts of
the alimentary tract are alkaline during digestive activity and either
neutral or weakly alkaline at other times. Hence, if we make use of
these words in insect physiology, it must be with the understanding
that no chemical significance is implied. The ventriculus is very
commonly called the “ chyle stomach ” but there is probably no reason
for calling it a “ chyle stomach” any more than a “ chyme stomach,”
and likewise there is no reason for supposing that the intestine does
not contain chyle—in fact, it almost certainly does. The word
“chyle” may be used with entire propriety in insect physiology to
signify the completed products of digestion, but to designate a part
of the alimentary tract as the “ chyle stomach ” is applying the term
without an adequate basis of facts.

The contents of the ventriculus are surrounded by several concen-
tric layers of thin filmy membrane which form an interior tube ex-
tending the entire length of the stomach and reaching down into the
102 THE ANATOMY OF THE HONEY BEE.

anterior end of the intestine. This tube can be very easily seen by
carefully cutting open the outer walls of the ventriculus, but it is
best demonstrated by transverse microtome sections of a specimen
prepared for histological purposes. Such a section is shown by figure
46 A. A small amount of-solid food matter (gq) is seen in the cen-
ter of the specimen, surrounding which are numerous irregular con-
centric rings of membrane (Pmb), some adhering to each other in
places, others entirely free, most of them structureless, but others
partly cellular. These are known as the peritrophic membranes
(Pmb). They keep the solid contents of the stomach away from the
epithelial walls, from which, as will be presently explained, they are
given off from time to time.

The walls of the ventriculus (fig. 46 A) are thick and consist of
numerous cells (Zpth) apparently very irregularly arranged. On
their inner surfaces is a thin intima (/n¢) and on their outer surfaces
a still finer basement membrane (BJ/). Outside of the last are two
layers of muscles, the external layer consisting of longitudinal fibers
(ZMcl) and the inner of transverse ones (7'Jfcl). Numerous an-
nular depressions of the walls form internal folds (fig. 45), but any
part of the ventricular wall can be stretched out into a flat sheet,
which is then seen to be full of little pits, giving the whole a screenlike
appearance. Sections show that the pits result from circular invagi-
nations of the basement membrane (fig. 46 B, BA/), and that at the
bottom of these pockets the cells are very small and convergent, while
those on their lips are very large. Figure 46 B is a very perfect
example of this structure of the epithelium, which is usually more
or less obscured, as in figure 46 A, by a great proliferation of small
cells from the lips of the cups—and then a large section seldom gives
a symmetrical view of all the parts. The cups are all filled to over-
flowing by a gelatinous mass (pp) which fuses over their edges into
a continuous coating beneath the intima over the entire inner surface
of the epithelium. This mass appears to be formed mostly by the
cells at the bottoms of the cups, for the outermost of these (fig. 46 B,
ar) often insensibly fade into it.

Figure 46 E shows an opposite condition of the epithelial cells.
Here the lip cells of the cups appear to be very actively dividing,
and proliferating a great number of small cells (Zz) which float
off into the gelatinous covering. These discharged cellules are all
nucleated, but their protoplasm does not stain in preparations and
consequently they appear clear and transparent as compared with the
cells they apparently come from. The writer has not been able to find
any of these cells actually in the process of division, but a comparison
of figures B and E (which are camera lucida drawings and not dia-
grams) would certainly suggest that the condition of the cells in E
has resulted from a very active division of the cells of the walls and
THE ALIMENTARY CANAL AND ITS GLANDS. 1038

lips of the cups, which are quiescent in B. Comparing this with
what is known to take place in other insects during digestion, there
is every reason for believing that the proliferated cellules are filled
with the digestive secretion, and that E represents a stage immedi-

 

Fig. 46.—Histological details of alimentary canal of worker: A, cross section of ventriculus
showing peritrophic mémbranes (Pmb); B, section of wall of ventriculus showing
epithelial cups with cells in resting condition and covered by gelatinous mass (pp) 3;
C, section of Malpighian tubule; D, cross section of small intestine; E, section of
ventricular epithelium after formation of numerous small digestive or enzyme cells
(Enz) given off into gelatinous matrix (pp); F, section of anterior end of rectum
through rectal glands (RG@I) ; G, part of slightly oblique section through posterior end
of ventriculus and anterior end of small intestine, showing openings of Malpighian
tubules (Mal) into the latter.

ately subsequent to one of greatest secretive activity, in which there
is a large number of little cells (Znz) highly charged with the
enzyme-containing digestive juices imbedded in a gelatinous matrix
covering the inner surface of the epithelium. This matrix next
104 THE ANATOMY OF THE HONEY BER.

separates itself from the ends of the remaining epithelial cells, which
at the same time secrete a new intima over their inner surfaces. The
lower part of figure 46 A shows this indisputably. «Lhe whole thing,
then, finally contracts about the food and, as the digestive cellules
give up their contents, shrivels and shrinks and becomes a peritrophic
membrane. In figure A the outermost peritrophic layer is still in
both conditions—its dorsal part is shrunken to a thin membranous
form, while its lower part is gelatinous and filled with secretion
cellules, though it is separated from the epithelium by a new intima
and is detached at intervals from the latter. Beneath the new intima,
furthermore, is seen at places the formation of a new gelatinous mass.
Some of the inner peritrophic layers shown in A also retain remnants
of cells.

Figure 46 A is drawn from a specimen which is typical of all in
several series of sections through the ventriculus. The peritrophic
layer partly adhering to the epithelium is no artifact, because the
same condition may often be directly observed in dissections of fresh
specimens. In the opposite end of the series from which the specimen
was selected this layer is entirely free from the epithelium.

The peritrophic membrane has been described in some insects as
being a prolongation from the intima of the proventriculus, the ven-
triculus itself being supposed never to secrete an intima. It is per-
fectly conceivable that the anterior end of the membranes might be
generated by the outer cellular layer of the proventricular funnel and
remain attached to it after the rest of it had become free from the
ventricular wall, and thus give the appearance of belonging to the
proventriculus. The writer, however, has several sets of longitudinal
sections through these parts in the bee, but none of them nor any dis-
sections made show such a condition.

Absorption is commonly supposed to take place largely in the ven-
triculus. If so, the food must pass through the several peritrophic
membranes and then through the thick epithelium. It is entirely
possible that it may do so, but the pollen contained in the ventriculus,
as already stated, shows little or no evidence yet of digestion and does
not begin to do so until it reaches the small intestine. On the other
hand, the dark mucilaginous slime of the ventriculus does not appear
in any quantity in the much drier contents of the small intestine.
Therefore it may be supposed that this slime contains the sugar ele-
ménts of the food and that the latter are principally digested in, and
absorbed from, the ventriculus. The absorption of the proteids and
hydrocarbons must take place in the intestine and rectum since these
food elements in the bee’s diet are derived only from the pollen.
However, these conclusions are purely tentative, being based on the
writer’s observation of the contents of the different parts of the ali-
mentary tract, which, while fairly extensive and continued through
THE ALIMENTARY CANAL AND ITS GLANDS. 105

most of a year, are confessedly not nearly adequate to serve as a
basis for conclusive statements on the digestive process. They are
sufficient, however, to show the utter lack of a basis in facts for many
other opinions on this subject.

Cheshire (1886) describes two kinds of cells in the ventricular
epithelium, “one secreting a digestive fluid (gastric juice) from the
surrounding blood into the stomach, so that the pollen grains may be
made fit for assimilation by a transformation not unlike that lique-
fying gluten in our own case; the other absorbing the nutrition as
prepared and giving it up to the blood.” Though Cheshire refers
to his figures to show these two kinds of cells, he does not point out
which are which—in fact, he does not even designate two different |
kinds in his drawings nor even represent two ignds:

The small intestine (fig. 42, S/nt) forms ‘a loop upon itself and con-
stitutes a narrow tube comme came the stomach (Vent) with the large
intestine or rectum (fect): Its anterior end is somewhat enlarged
and carries the circle of malpighian tubules (Jfal). Its epithelium
(fig. 46 D, Zpth) is very simple and is thrown into six longitudinal
folds that project into its lumen. On the outside is a thick sheath
of transverse muscle fibers (7d/cl) with distinct nuclei (Vu). The
latter are designated by Cheshire (1886) as “longitudinal muscles”
(see his figure 14 D), but this is a very evident mistake—the small
intestine has no longitudinal muscles at all. It is evident that the
folds of the epithelium permit the ordinarily narrow tube to expand
very considerably when necessary to allow the passage of a large
amount of food. The contents of the small intestine are usually
drier than those of the ventriculus, consisting principally of masses
of partly digested pollen, that is to say, the contents of the grains are
partly dissolved out—presumably signifying that they are under-
going digestion. There is usually only a small amount of the brown
slime present such as fills the ventriculus.

The Malpighian tubules (fig. 42, M/a/) are wrapped and coiled about
one another and about the viscera of the abdominal cavity. There
are about 100 of them in the honey bee and they all open separately
into the anterior end of the intestine. Each is a very long thread-
like tube consisting of a single layer of epithelial cells provided with.
a very delicate basement membrane aud intima (fig. 46 C). The ends
of many of the cells are clear and bulge into the lumen. Figure
46 G shows a section through the junction of the ventriculus and the
intestine where the tubules open by narrow necks penetrating the
epithelium. The wall of the ventriculus forms a short double-layered
fold (VentVlv) projecting backward into the anterior end of the
intestine, behind which are the orifices of the Malpighian tubules.
The section from which figure G was drawn is cut somewhat obliquely
and takes in this fold only on one side.
106 THE ANATOMY OF THE HONEY BEE.

The Malpighian tubules are regarded as excretory in function and
are supposed to remove from the blood the nitrogenous waste prod-
ucts resulting from metabolism. Minute crystals of urates are often
to be found in them and they probably perform the work of the
kidneys in vertebrate animals.

The large intestine (fig. 42, Rect), called the rectum in insects, is
an enormous sac which may lie limp and flabby in the rear part
of the body or it may be so immensely distended by the amount of
its solid and liquid contents as to occupy a large part of the abdomi-
nal cavity. The recognizable elements of the material within it
consist mostly of the empty shells of pollen grains or of grains hav-
ing their contents greatly shrunken and distorted—presumably as
a result of the absorption of the protoplasm, although a considerable
number are usually present which are only slightly digested, while
there are always to be observed a few perfect and fresh-looking
grains showing no evidence at all of digestion. The rest of the in-
definite mass of solid rectal material consists of some unrecognizable,
finely triturated substance, probably derived in part from fragments
of the peritrophic membranes. There are always present a few bits
of feathered bee hairs.

The epithelium of the rectum is, like that of the oesophagus, rudi-
mentary, being distinguishable only by the nuclei (fig. 46 F, M2)
remaining in the outer layer of the thick transparent intima (Jnt).
Outside of this is an external layer of longitudinal muscle fibers
(Z4Mcl) and an inner layer of transverse fibers (7'J/cl). The intima
(Znz) is thrown into numerous folds whose edges converge, forming
pocketlike grooves between them in which are lodged small masses
of the rectal contents. This is very suggestive that absorption takes
place in this part of the alimentary tract, although it is not com-
monly supposed to do so, but if the pollen is not fully digested until
it reaches the rectum, how can it be absorbed by the anterior part
of the alimentary canal?

The so-called rectal glands (fig. 42, RG2) consist of six hollow
epithelial tubes (fig. 46 F, GZ) and are the only parts of the rectal
epithelium in which the cells are well developed. The cells on the
outside of each “ gland” are small, but the inner ones are very large
and are covered by a thick layer of dark chitin (Jnt). The lumen
is intercellular and does not communicate with that of the rectum.
When the rectum is distended the “ glands” bulge out on the surface
as six short opaque ridges (fig. 42, G7), but when it is empty they
sink into the walls as in figure 46 F. Nothing is known of the
function of these organs, and their glandular nature is entirely con-
jectural. If they are glands, it is not clear why the intima should
be so especially dense on their inner faces.
THE CIRCULATORY SYSTEM. 107

VII. THE CIRCULATORY SYSTEM.

The liquid medium that distributes the digested food from the
alimentary canal to the cells of the body tissues is called the blood,
and the contractile organ that keeps the blood in motion is the heart.
In vertebrate animals the blood is contained entirely within tubes
called arteries and veins, but in insects and most other invertebrate
animals the blood simply fills the empty spaces between the viscera
of the body-cavity, which spaces may, however, constitute definite
channels or sinuses, and may even be shut in by special membranes.
Besides carrying and distributing the digested food that is absorbed
into it in solution, the blood of animals generally has also to dis-
tribute oxygen to the tissue cells and carry off their waste products.
Oxygen is obtained from the air and, like any other gas, is soluble
in liquids. Hence it is present in the blood not in the form of small
bubbles of gas but in solution, just as it is in all water exposed to the
air. The respiratory system (see page 116) is simply a special con-
trivance for bringing air into close proximity to the blood so that
its gases may diffuse into the latter, but many soft-bodied animals
like earthworms absorb air directly through the skin. Vertebrate
animals have a substance in their blood called hemoglobin which is
contained in the red corpuscles and has a great capacity for absorb-
ing oxygen. It, therefore, enables the blood to carry much more of
this gas than could be dissolved simply in its plasma. Invertebrate
animals do not need so much oxygen as vertebrates, and, therefore,
most of them can get along with that which dissolves in the color-
less blood plasma without the special aid of hemoglobin. Most
insects, however, being excessively active creatures, must have a
rapid metabolism in their cell tissues, and consequently they need
much oxygen to consume the product of this metabolism, but they
belong to the class of animals without red blood and, hence, nature
has provided them with another means of obtaining a special supply
of air, namely, a set of air-tubes branching minutely over nearly all
the internal organs, the tissues, and even most of the cells in the
body. (See “The Respiratory System,” page 112, for discussion of
oxidation and removal of waste products.)

The blood of insects is usually a colorless liquid containing opaque
granular cells or corpuscles floating in it. There are no special blood
vessels, but there are very definite channels between the muscles and
viscera through which the blood flows, while conspicuous membranes
stretched across the dorsal and ventral walls of the abdomen (fig. 1,
DDph and VDph) inclose special dorsal and ventral sinuses which
play an important part in the circulation. These membranes, called
diaphragms, are rhythmically contractile, and contribute much to
108 THE ANATOMY OF THE HONEY BEE.

maintaining the circulation of the blood. ‘ The heart (fig. 1, Ht) is
located in the dorsal sinus, which latter is therefore often called the
pericardial chamber. The pulsations of the diaphragms are produced
by fine muscle fibers lying in their walls. These are usually ar-
ranged in a number of fan-shaped bunches on each side radiating
from the edges of the diaphragm (fig. 47, DphMJcl) toward the mid-
dle, where most of them are continuous with the fibers from the oppo-
site side. It used to be supposed that those of the dorsal diaphragm
produced the expansion of the heart, and they were for this reason
called the “ wing muscles of the heart,” but the latter organ is now
known to be a muscular tube and to contract and expand by its own

 

Fic. 47.—Dorsal diaphragm of drone, from one segment and adjoining parts of two
neighboring segments, showing median heart (Ht) as seen through transparent dia-
phragm (DDph), fan-shaped bunches of diaphragm muscles (DphMcl), and lateral
tracheal sac (Tra8c) giving off sac-bearing trunks into pericardial chamber above
diaphragm.

power. In some insects the muscles of the dorsal diaphragm form a
meshwork of fine fibers surrounding numerous large and small holes
in the membrane, which probably permit the entrance of blood into
the sinus above, but in most species the diaphragm is imperforate
and the blood enters the pericardial chamber above its scalloped edges
(figs. 1 and 47).

The heart of insects in general is a long narrow tube (fig. 1, H¢)
situated in the dorsal sinus or pericardial chamber of the abdomen
along the midline of the body. It is swollen toward the middle of
each segment into a heart chamber (ht) which presents a vertical
slitlike opening or ostiwm (Ost) on each side. Theoretically, in
THE CIRCULATORY SYSTEM. 109

generalized insects, there should be a chamber to each segment, but
the heart is variously shortened from both ends so that the chambers
are always fewer than the segments. The posterior end of the heart
is closed, but its anterior end is produced into a long narrow tube
called the aorta (fig. 1, Ao) which extends through the thorax and
opens by a few simple branches into the cavity of the head.

. The heart of the bee (fig. 1, Zé) consists of only four chambers
(1ht-4ht) lying in the third, fourth, fifth, and sixth segments of the
abdomen. In the front of this part of the body it bends downward
and forms a large convoluted loop (7) of about 18 folds where it
passes through the abdominal constriction. All of this convoluted
part really belongs to the abdomen, since it lies in the propodeal part.
of the apparent thorax, which is the true first abdominal segment.
The aorta (Ao) extends forward from here as a very fine tube making
a large arch between the muscles of the thorax and then enters the
back of the head. According to Pissarew (1898) the convolutions
of the anterior end of the heart are peculiar to the honey bee, being
absent in its nearest relatives such as Bombus and Mfegachile. The
heart walls, as before stated, are muscular and produce a rhythmical
contraction of the tube whose pulsations follow each other from be-
hind forward. Thus the contained blood is driven out of the anterior
end of the aorta into the head, where it bathes the brain and the other
organs of this region, and then flows backward, percolating through
the spaces between the organs of the thorax.

From the thorax it enters the cavity of the ventral sinus—not the
general abdominal cavity, at least in the bee—and is pumped back-
ward by the pulsations of the ventral diaphragm and dorsally over
the inner walls of the thorax and through definite channels about all
the viscera, finally collecting in the dorsal sinus where it again enters
the heart through the lateral ostia. The lips of the ostia are pro-
vided with small membranous lobes which project inward and con-
stitute valves that prevent the expulsion of the blood. A similar
valve is placed at the anterior end of each chamber of the heart to
prevent a possible backward flow.

In the bee, both the dorsal and the ventral diaphragms are well
developed, the former (fig. 1, DDph) extending from the third
abdominal segment to the seventh, inclusive, while the latter (VDph)
extends from the abdominal constriction to the eighth segment.
The ventral diaphragm is much more muscular than the dorsal and
its pulsations, which are very strong, follow each other from before
backward. They may easily be observed by removing the top of
the abdomen from an asphyxiated bee. The ventral sinus is very
ample, inclosing the nerve cord of the abdomen, and receives into
its anterior end the blood channels of the thorax, so that the latter
110 THE ANATOMY OF THE HONEY BEE.

communicate with the general cavity of the abdomen only through
the ventral sinus.

The dorsal diaphragm (fig. 1, DDph) ends by a free transverse
edge near the front of the third abdominal segment. <A part of it is
shown by figure 47 extending across one segment and the adjoining
parts of two others. The fan-shaped bunches of muscle fibers
(Dphifcl) are seen radiating from the anterior edges of the terga
toward the midline, where they are mostly continuous with those
from the opposite side, only a few of the anterior and posterior ones
ending free in the membrane of the diaphragm. The latter is imper-
forate, but its edges are deeply scalloped between the points where
the muscles are attached, allowing free entrance to the blood from
the intervisceral channels of the abdomen. The dorsal surface of
the diaphragm is covered by a network of cells (figs. 47 and 48,
DphCls) arranged in flat branching and fusing bands. These cells

  

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Fic, 48.—Small part of dorsal diaphragm of drone, showing bands of flat diaphragm cells
(DphCls), the diaphragm membrane itself (Dphmb), and the muscle fibers (DphMcl).

may be called the diaphragm cells to distinguish them from the
pericardial cells to be described later.

The abdominal circulation is very easy to observe in a living
bee. The best way to demonstrate it is to pin an asphyxiated bee
to a block of cork or paraffin and remove the top of the abdomen
by making an incision with a small pair of scissors clear around it.
Gently pull the alimentary canal to one side so as to expose the
ventral diaphragm, which will be observed pulsating strongly back-
ward. Next cut a small hole in the top of the thorax and insert
into it a drop of some stain in a water solution (the writer used
carmalum). Almost immediately this will appear in the ventral
sinus of the abdomen, in which it is pumped backward by the dia-
phragm, and from which it goes upward through invisible channels
between the air sacs and the alimentary canal and especially up
THE CIRCULATORY SYSTEM. 111

wide channels against the lateral walls of cach segment. It does not
run out free into the abdominal cavity, however, unless through a
rent, nor does it enter the latter from the thorax except by way of
the ventral sinus. The dorsal circulation of course can not be
observed in this specimen because the back is removed. Therefore,
take another bee and fasten it in the same manner, but make simply
a shallow median slit along the back, thus exposing the dorsal sinus
and the heart from above. Now insert a drop of stain into the
thorax as before. After about two minutes this will appear in per-
ceptible amount in the dorsal sinus, very much diluted, to be sure,
with the blood, but there will be enough to give white blotting paper
a distinct red tint. In a short time the heart becomes filled with
the stained blood and appears as a red tube along the median line.
The dorsal sinus contains not only the heart but also two pairs of
pericardial air sacs in each segment. These are seen entering the

TraSc DD ph e HivTraSc Tits

        

Fie. 49.—Pericardial chamber of one segment in worker, seen from below looking through
transparent dorsal diaphragm (DDph), showing median heart (Ht), lateral pericardial
air sacs (HtTraSc) given off from large lateral sacs (TraSc), and the padding of
pericardial cells (HtCls) against inner surface of tergum (T').

sinus from the large lateral air sacs of the abdomen (7’raSc) in
figure 1 and also in figure 47. In the latter the heart (ZH?) is seen
along the median line as it shows through the diaphragm. Figure
49 gives a view of the pericardial sinus as seen from below, in one
segment, by focusing through the transparent diaphragm (DDph).
In the middle lies a chamber of the heart (H?¢) with the slitlike
ostium on each side. Laterally are the four pericardial air sacs
(HtTraSc) giving off branches that ramify profusely upon the
heart. Above the heart and the air sacs is a thick bed of large
granular cells (Hts) which make a soft padding between the hard
tergal wall and the delicate organs of the sinus. These are called
the pericardial cells. They may have some physiological function,
as has often been supposed, but if so no one has decided what it is.
112 THE ANATOMY OF THE HONEY BEE.
VIII. THE RESPIRATORY SYSTEM.

The lives of all animals depend upon a constant distribution of
free oxygen gas throughout their bodies. This oxygen, continually
inhaled and exhaled, is not used in the formation of tissues, it does
not become a part of the living protoplasm of the animal—it is the
physiological scavenger that eats up certain waste products of me-
tabolism which are deadly to the system unless constantly removed or
changed into less harmful compounds. The action of oxygen upon
these waste substances within the body is comparable with ordinary
combustion in that it results in the formation of carbon dioxid gas
and water and in the generation of heat. Since the air, which is com-
posed of both oxygen and nitrogen, is the source of the oxygen supply,
the ordinary breathing processes involve an inhalation also of nitro-
gen gas, and the tissues become permeated with it as well as with
oxygen. The nitrogen of the air, however, is not known to serve any
physiological purpose in the body, its presence being simply unavoid-
ably incidental to the inhalation of oxygen. While oxygen and nitro-
gen are two most important food elements, the tissues.of animals can
not make use of either in the gaseous condition, but must be supplied
with substances containing these elements in combination with others
in the form of solid and liquid food stuffs taken into the alimentary
canal. Hence, air is not a food, and the respiratory system is to be
regarded as chiefly excretory in function.

The means by which different animals receive oxygen into
their systems are various. All aquatic breathers of course use
that which is naturally dissolved in water. Many of the lower: ani-
mals absorb air directly through their skins and into their tissues,
while the carbon dioxid escapes the same way. Others that live in
the water and whose bodies are covered by an impervious skin or
shell have thin-walled, hollow, branching appendages, called gills,
through which the blood circulates freely and through whose walls
the necessary exchange of gases takes place. Land animals very
commonly have some sort of an invagination from the exterior which
allows the air to enter thin-walled tubes or cavities and be absorbed
into the blood. Land vertebrates have a tube opening from the back
of the mouth whose inner end branches profusely and forms a pair of
organs called the lungs, through which the blood circulates freely in
delicate tubes that allow the transfer of gases. Insects, finally, have
a system of internal air tubes, called trachew, opening to the exterior
by a number of small orifices, called spiracles, situated along the sides
of the thorax and abdomen, which give off branches that ramify
minutely to all parts of the organism, thus virtually making a lung
of the entire body. The trachee are thin tubes made of flat epithelial
THE RESPIRATORY SYSTEM. 113

 

I'ic. 50.—Tracheal system of worker as seen from above, one anterior pair of abdominal
sacs (fig. 1, 9) removed and transverse ventral commissures of abdomen not shown.

22181—No. 18—10-—_8
114 THE ANATOMY OF THE HONEY BEE.

cells lined with a delicate layer of chitin. The latter, however, is
strengthened by circular thickenings which give the appearance of
an internal spiral thread, but a closer examination shows that each
thickening makes only a few turns and that several lie in parallel
bands. This structure is for the purpose of maintaining an open
passageway for the air through the very thin-walled tubes. The
trachee branch into fine capillaries and these terminate in excessively
delicate end-tubes. In some cases it is easy to see that a great
number of capillary branches surround the cells of a tissue, if
they do not actually enter the cell walls, but in others it can not be
shown that the trachee really penetrate below the surface of a mass
of cells. : :

Gases in solution, like solids, pass freely back and forth through
moist animal membranes, going in the direction of the least pressure
of each particular gas. By this simple method the gases go back and
forth through the walls of the gills, lungs, or air tubes and permeate
the tissues themselves. Vertebrate animals, as already explained,
have a red substance in the blood called hemoglobin which has a
very great oxygen-absorbing power and which greatly increases the
oxygen-carrying power of the blood, but still a certain amount of
oxygen is carried in solution by the liquid or plasma of the blood.
Now, the blood of insects has none of this hemoglobin and all the
oxygen it can carry is that which dissolves in its plasma, but, on
account of the extensive ramification of the air tubes, it is not neces-
sary for the blood to distribute the oxygen to the organs. It is usually
stated that the blood in insects does not carry oxygen at all, except
for its own use, but it would seem physically impossible that the gases
should not diffuse out of the fine terminal air-tubes into the blood
when they do so in all other cases. If the blood of a crab or crayfish
is capable of carrying enough oxygen in solution to supply the wants
of the body, there is no reason why that of an insect, which has much
better facilities for obtaining air, should not do the same. Further-
more, we can not suppose that the products of katabolism have to
accumulate about the end trachez in order to be oxidized. They are
produced wherever metabolism is going on, which is everywhere in
the living cell substance, and, hence, the latter must be permeated
with oxygen in solution, which must also be in the blood along with
the carbon dioxid formed. The carbon dioxid diffuses back into the
end trachee from the blood. Therefore, while the great extent of the
tracheal system in insects relieves the blood of the work of distribut-
ing the oxygen, the blood must nevertheless serve as an intermediary
medium for both the oxygen and the carbon dioxid between the fine
terminal tracheal branches and the cells.

It has sometimes been suggested that certain large cells called
enocytes, found especially in connection with the tracheal system,
THE RESPIRATORY SYSTEM. 115

function as intermediaries between the trachee and the cells, but
Koschevnikov (1900) has shown that these cells appear to be tem-
porary storehouses for waste products from the tissues—presumably
uric acid compounds which have been already oxidized. Even the
fat-body has been regarded as a sort of lung in which oxidation takes
place, but there is no evidence to support this theory, although, for
that matter, there is little evidence in favor of any theory in insect
physiology. :

The process of metabolism, or the vital activity of the cells them-
selves, results in a breaking down of the complex and highly unstable
protoplasmic molecules into chemical substances of much simpler con-
struction, and it is these by-products of metabolism that are attacked
by the oxygen in the blood furnished by the respiratory system. Pro-
toplasm consists principally of the elements carbon, oxygen, hydro-
gen, and nitrogen, and the oxidation process results, as before stated,
in the formation of carbon dioxid (CO,) and water (H,O), while
the residuary products are mostly organic compounds of nitrogen
related to uric acid (C,;H,N,O,) and urea (CON,H,). The carbon
dioxid is a soluble gas which diffuses into the end tubes of the trachezx
and is exhaled. <A part of the water at least is given off with the
“breath ” in the form of water vapor, for drops of it can be collected
by inclosing bees or any insects in a tube for a short time. The nitro-
gen compounds and probably a part of the water are dissolved in the
blood and removed by the Malpighian tubules, which are the kidneys
of insects.

Besides this oxidation of waste products, which allows the process
of metabolism to go on unhindered, the inhaled oxygen serves also
another purpose, namely, that of maintaining the body heat. Al-
though insects are usually classed as “ cold-blooded ” animals, they
nevertheless maintain a temperature which is always higher than
that of the surrounding air and is often a number of degrees above
it. It is well known that the temperature of a beehive during the
brood-rearing season is almost as high as that of the human body,
and that even during winter it remains at nearly 80° F.; but this is,
of course, due to the accumulation and condensation of the warmth
from the bodies of a great many bees, and is much higher than the
temperature of any bee outside of the hive. In our own bodies
certain substances are consumed by oxidation in the blood simply
to produce the necessary heat energy for maintaining metabolism,
and hence it seems reasonable to suppose that the same thing takes
place in insects, although of course to a much less degree.

There are generally ten pairs of spiracles or breathing apertures
in insects, two being situated on the sides of the thorax between
the segments, but probably belonging to the mesothorax and the
116 THE ANATOMY OF THE HONEY BEE.

metathorax (although the first is often regarded as prothoracic),
while the other eight are situated on the sides of the first eight
abdominal segments—in the bee on the lateral parts of the terga
(figs. 82 and 33, Sp). The breathing apertures are usually pro-
vided with a closing apparatus of some sort consisting of the swollen
lips of slitlike spiracles, of a small lid, or of a flexible and collapsible
chitinous ring, each with special occlusor muscles attached. In the
bee a chitinous band surrounds the tracheal tube opening at each
spiracle, a short distance from the aperture, and has two opposite
loops projecting on the same side, connected by a muscle whose con-
traction approximates the two halves of the band so as to close the
lumen of the trachea.* It is supposed that after an inhalation the
spiracles are closed momentarily, so that the first force of the ex-
piratory contraction of the abdomen is exerted against the air shut
in the trachex, with the result of driving it into the extreme tips
of the latter—the spiracles then opening, the rest of the contraction
is expended in exhalation.

The internal tracheal system consists, among insects generally,
of a large tracheal trunk lying along each side of the body, connected
by short tubes with the spiracles and by transverse commissures with
each other, while-they give off segmental branches into the body
cavity which ramify minutely upon the organs and tissues. In the
thorax specially large tubes are given off on each side to the legs
and to the bases of the wings, while in the head others go to the
eyes, antenna, and mouth parts. The whole body is thus virtually
a lung with ten pairs of openings along the sides.

The tracheal system of the bee (figs. 1, 50, and 51) is best developed
in the abdomen, where the longitudinal trunks are enlarged into two
enormous lateral air sacs (7raSc), which are of greatest diameter in
the anterior end of the abdomen. They are segmentally connected by
large transverse ventral commissures (fig. 51, 77aCom), most of which
are themselves distended into small air sacs. Dorsally the lateral
sacs give off in each segment a large tube which divides into two sac-
culated branches (figs. 49 and 50, Ht7raSc) that enter the pericardial
chamber and supply the heart and pericardial cells with trachee. In
the thorax a large sac lies on each side of the propodeum (figs. 1 and
50, 7), which bears a short tube opening to the first abdominal
spiracle (figs. 21 and 50, Sp). Above these sacs is a narrow trans-
verse median one (figs. 1 and 50, 8) occupying the large cavity of
the turgid mesoscutellum (fig. 21, Sc/,). In the ventral part of the
thorax there is a large median posterior sac (figs. 1, 50, and 51, 5)

 

¢¥Wor a detailed description of the spiracles in the bee and their occlusor
apparatus see Djathchenko (1906).
THE RESPIRATORY SYSTEM. 117

‘TraSc
Coormmry~ oe

  
  
 
   

 
 

10

Mg
Wh

Hi

ep My
ell

dal ill
ult

  

Fig. 51.—Tracheal system of worker showing lateral and ventral parts as seen from
above, with dorsal sacs and trunks removed in both thorax and abdomen.
118 THE ANATOMY OF THE HONEY BEE.

which gives off trunks to the middle and hind legs and a large sac
on each side (fig. 51,6 and 6) to the ventro-lateral walls of the thorax.
Two large strong tubes (figs. 1, 50, and 51, 77ra)—the only trachex
in the bee’s body well developed as tubes—extend backward from the
head through the neck and prothorax to the first thoracic spiracles
(figs. 50 and 51, 7Sp). Each of these gives off a branch which divides
into the trachea for the first leg and into another that connects with
the posterior ventral thoracic sac (5). An anterior median thoracic
sac (4) is connected with the two large anterior tubes near where these
enter the neck. In the head are a number of. large sacs which are
situated above the brain (see figs. 1, 50, and 51, 7), about the bases
of the eyes and optic lobes (see figs. 1 and 50, 2), and above the bases
of the mandibles (see fig. 1, 3).

Nearly all of the trachez in the bee’s body are excessively delicate
and their walls mostly lack the spiral thickening that ordinarily holds
a tracheal tube open. They are consequently very distensible and,
when inflated, they show as opaque glistening white vessels, which,
however, when empty, are extremely difficult or actually impossible to
see. The smaller branches are so numerous and flabby in the thorax
and the legs (fig. 1, Z7ra) that they appear to form everywhere
meshworks or sheets of tiny glistening air-cavities imbedded between
the muscle fibers. Only the large trunks in the anterior part of the
thorax have the normal tracheal appearance.

The body of the bee is thus most abundantly aerated, probably
more so than that of any other insect. The numerous large and
small sacs form great storehouses of air—tanks containing reserve
supplies of oxygen. They are not present for the purpose of lighten-
ing the weight. of the body, because inflation with air does not
decrease the weight of any object surrounded by air.

The respiratory movements are limited to the abdomen in the bee
on account of the solidity of the thorax. They vary a great deal
according to the activity of the individual. While sitting quietly
at the entrance of the hive or walking slowly about, bees usually
exhibit almost no respiratory motion, only a very slight vibratory
trembling of the abdomen being noticeable. Others that are walk-
ing hurriedly about lengthen and shorten the abdomen very percepti-
bly, the motion being specially pronounced at the tip. A bee that
has just alighted after flying exhibits still more pronounced abdomi-
nal movements, not only a contraction and expansion but an up-
and-down motion as well. When a bee is becoming asphyxiated in
a killing bottle the extension and contraction of the abdomen is most
pronounced, although much slower than in the ordinary breathing
movements, .

The muscles of the abdomen that produce respiration have been
described by Carlet (1884), who distinguishes seven different sets of
THE FAT BODY AND THE G@NOCYTES. 119

them as follows: There are two dorsal sets: (1) The internal dorsal,
going from the anterior edge of one tergum to the anterior edge of
the next following tergum, and (2) the external dorsal, going from
the lateral edge of one tergum to the corresponding edge of the fol-
lowing tergum. Both of these are expiratory, since their contrac-
tions bring the two segments together. On the sides are three sets:
(3) The external oblique, going from the anterior edge of each tergum
to the side of the corresponding sternum; (4) the internal oblique,
crossing under the last from the anterior edge of each tergum to the
side of the preceding sternum. These two sets are likewise expira-
tory, because their contractions approximate the terga and sterna.
The third set of lateral muscles is (5) the transverse, lying between
the overlapping surfaces of each tergum and its corresponding
sternum and being, therefore, inspiratory, because the contraction
separates the terga and sterna. Finally, there are two sets of ventral
muscles: (6) The external ventrals and the internal ventrals, forming
a letter Jf between the anterior edge of each sternum and the one
following, and (7) the interventral, situated between the overlap-
ping surfaces of consecutive sterna and causing their separation by
contraction. These last are therefore also inspiratory.

It would thus seem that the abdomen is much better equipped with
expiratory than with inspiratory muscles. Perhaps the expansion
is partly due to elasticity, and perhaps, also, it is true that the abdo-
men contracts upon the full trachez and air sacs, before the spiracles
open to allow exhalation, in order to drive the air into the farthest
recesses and terminal tubes of the tracheal system, which necessitates
an extra contractive force.

IX. THE FAT BODY AND THE G@NOCYTES.

The fat tissue of insects is not miscellaneously distributed through
the tissues, imbedded beneath the skin and packed between the
muscles, but is disposed in sheets and strands within the body
cavity, especially in the abdomen, or forms a definite mass, the
fat body. The fat cells are large and extensively vacuoled with
clear globules of fatty oils. In some insects the fat bodies have a
brilliant yellow, golden, or orange color. Associated with the fat
cells are other much larger and often gigantic cells, called wnocytes,
attaining the largest size of all the cells in the body except the eggs.
They were first discovered in segmental clusters attached to the
trachee near the spiracles, but they are now known also to be scat-
tered through the depths of the body cavity, where they occur im-
bedded especially between the fat cells. The term “ cenocyte ” signi-
120 THE ANATOMY OF THE HONEY BEE.

fies merely that those cells first observed by Wielowiejski, who gave
them this name, were slightly wine-colored.

Both the fat cells and the cenocytes of the honey bee have been
specially studied by Koschevnikoy (1900), who gives the history of
the fat body as follows: In the larva it consists of gigantic lobes, the
cells of which are in general all alike and so closely packed in 30
or more layers that, in the younger stages, most of them assume
angular forms. Many of them are binucleate, and the protoplasm
is strongly vacuolated except for a small area about the nuclei. In
the full-grown larve the fat cells become globular and filled with a
number of round granules, which, during the early part of the pupal
stage, are set free by a dissolution of the cell walls and float free in
the body cavity. In pupe a little older, having even but a very
thin chitinous covering, the adult fat body is fully formed, and yet
neither the disappearance of the larval granules and nuclei nor the
formation of new adult fat cells is to be observed. It seems that
the granules of the larval fat cells, set free at the beginning of
histolysis, are reassembled about the nuclei to form the fat cells of
the adult. In the very young imago the cells of the fat body are
very distinct, and each possesses a considerable amount of protoplasm,
with enormous vacuoles which press upon all sides of the nucleus.
In old bees the vacuolation is much reduced and may even be entirely
lacking, while the cells become filled with a solid granular plasma.
Old workers examined in the fall show the fat cells united into
syncytia or masses in which the cell boundaries are lost, although
the nuclei remain distinct. A queen does not appear to form these
syncytia in old age.

The function of the fat body is still unsettled, but we do not
know of any reason why it should not be comparable physiologically
with the fat of vertebrate animals and constitute a reserve supply
of materials which can be used both as food and as a source of heat
oxidation. It has already been stated (p. 115) that insects main-
tain several degrees of body temperature. Some entomologists have
supposed that the fat body gives rise to the corpuscles of the blood,
others have believed it to be an excretory organ because concretions
of-uric-acid salts are often found associated with its cells, while
still others have regarded it as the seat of the combustion of waste
products by the tracheal oxygen. ,

The cnocytes of the bee are described by Koschevnikov (1900) as
enormous cells imbedded in the fat bodies. He says that those of
the. larva persist into the pupal stage where they undergo dissolu-
tion and disappear, while new imaginal cenocytes are formed from
proliferations of the ectodermal epithelium, The new ones are at
THE FAT BODY AND THE CNOCYTES. 121

first small and increase about five times in diameter before reaching
their adult proportions. The fat cells and the cnocytes, although
closely associated with each other, are easily distinguishable by their
size and by their reaction in life to staining solutions. Koschevnikov
fed some bees honey or sugar sirup containing sesquichlorate of iron
and then, after a few hours, removed the fat body, washed it in ferro-
cyanide of potassium, and placed it in alcohol acidulated with hydro-
chloric acid. He found a precipitate of Berlin blue in the fat cells
while the cenocytes remained perfectly colorless. Thus he showed
conclusively that the two classes of cells are physiologically different
in life, although, he says, if a piece of dissected fat body be placed
in the staining solution the color diffuses alike throughout all the
cells.

The cnocytes have a golden brown pigmentation but no differen-
tiated contents in young workers and queens. In old workers, to-
ward the end of the summer, yellow granules begin to appear in
them. During winter and especially in early spring the cenocytes
of the workers contain a great number of these granules, but they are
present in greatest quantity in queens several years old, while in the
latter the fat cells also contain similar granules. Although
Koschevnikov admits that the chemistry of these granules is entirely
unknown, he thinks that they are undoubtedly excretory substances,
that the waste products of metabolism are first taken up by the cno-
cytes and then delivered to the blood, and that the accumulation of
the granules in the cells during old age means the loss of power
to discharge them, which brings on the decline in the life activity of
the bee. If this is so, then the cenocytes are, as he states, excretory
organs without ducts—cells which serve as depositories for waste
products.

According to this theory of Koschevnikov, the cenocytes might be
likened in function to the liver of vertebrate animals, which, accord-
ing to the present views of physiologists, is the seat of the splitting
up of the immediate nitrogenous products of katabolism, discharged
into the blood from the tissues, into those final compounds of nitro-
gen excreted by the kidneys.,

Wheeler® also describes the fat cells and cenocytes of insects
as perfectly distinct in their origins, the fat cells arising from the
mesoderm, which is the embryonic cell layer between that which
forms the outer body wall and that which forms the embryonic ali-
mentary canal, while the cenocytes are derived from internal pro-
liferations of ectodermal cells.

 

*Concerning the Blood Tissue of Insects. Psyche, VI, 1892, pp. 216-220,
233-236, 253-258, Pl. VIL
122 THE ANATOMY OF THE HONEY BEE.

x. THE NERVOUS SYSTEM AND THE EYES.

We have learned so far that the bee is a complex animal made up
of a large number of tissues and organs all definitely interrelated, and
we speak of these tissues and organs as performing their own special
functions. Yet, in itself, a mass of cells, even though a living mass,
is incapable of doing anything—it is inert unless stimulated into ac-
tion. The legs would not move, the heart would not beat, the glands
would not secrete, the respiratory movements would not be produced,
and the animal would cease to live were it not for a vital force that
incites them all into activity. This force is generated by certain
cells of the nervous system and is sent out to the other organs along
the nerve cords, but we know nothing more about it than simply that
it exists in living animals and is dependent upon the maintenance of
the nerve cells.

Now, in order that an animal may be “ alive,” it is not only neces-
sary that the muscles should be made to contract, the glands to secrete,
and all the other organs induced to perform their individual rdles,
but it is equally important that they should all work together and
accomplish definite results. The muscles must perform harmonious
movements to produce walking, flying, breathing, or swallowing, the
heart must beat in proper rhythm, the glands must secrete their juices
at the right time and in needed amounts. Hence, the functions both
of stimulation and coordination devolve upon the nervous system.
The nerve-cells generate a force which, delivered through the nerve-
fibers to the various organs, irritates the tissues into activity, but, at
the same time, the cells send out this force in such a methodical man-
ner that the activities produced in the different organs are definitely
correlated and cooperate in maintaining the necessary condition for
the life of the cells.

The nervous system, however, is more than simply the source of
these physical and chemical processes that constitute the visible phe-
nomena of life, for it is also the seat of all sense perceptions and, in
the higher animals, of consciousness. We do not know, however, that
insects possess consciousness—that they are actually aware of their
own existence, and we therefore do not know that they have conscious
sense perceptions. We do know that they are affected by external
objects—by light, heat, taste, odor, pressure, and perhaps sound-
acting upon specially sensitized cells of the ectoderm called sense
organs, but we do not know that the reaction of the individual is
anything more than the exhibition of a very highly developed re-
flex nervous system. It is most probable that bees do all that they
do—make the comb, store up honey and pollen, feed the young, attend
to the wants of the queen, and so on—without knowing why, and we
have no evidence that they are even conscious of the fact that they do
eo

THE NERVOUS SYSTEM AND THE EYES.

 

Fia. 52.—Nervous system of worker, dorsal view.

123
124 THE ANATOMY OF THE HONEY BEE. .

these things. Some authors have tried to prove that insects reason,
but the burden of proof is still with them. We can admit that in-
sects may be possessed of very slight conscious intelligence, but we
can not admit that any one has ever proved it. Of course, a great
deal of very interesting insect literature owes its readableness to the
fact that the author endows his subjects with human emotions and
some intelligence, or makes it appear that they consciously do things
from a blind sense of obligation. The bee of literature is often quite
a different creature from the bee of science.

If, then, we are forced to admit that we have no proof of intelli-
gence or of conscious sensations in insects, we have, on the other
hand, all the more evidence of a very high degree of nervous coordi-
nation. The body of a bee can be very greatly mutilated and the
creature will still remain “alive” as long as the nervous system is
left. intact. The segments can be cut apart and each will yet be able
to move its appendages as long as its nerve center is not destroyed.
This shows that there are numerous vigorous centers of nervous
stimulation, but proper coordination results only when all the parts
are together and intact.

The nervous system of insects (figs. 1 and 52) is comparatively
simple, consisting of a series of small nerve masses called ganglia
(Gig) lying along the mid-ventral line of the body, each two con-
secutive ganglia being connected by a pair of cords called the com-
missures.~ The ganglia contain the nerve cells, which are the source
of the stimuli sent out to the other tissues, while they also receive the
stimuli from the ectodermal sense organs. Thus there are incoming
or afferent stimuli and outgoing or efferent stimuli. The commis-
sures and the nerve-trunks that branch to all parts of the body con-
sist of fibers which are fine prolongations of the nerve cells. These
fibers are the electric wires that convey the stimuli to and from the
nerve centers and are of two kinds, afferent and efferent, according
to the direction of the stimulus each transports.

In a generalized embryo we should theoretically find a nerve gan-
glion developed from the ventral wall of each segment, making seven
head ganglia, three thoracic, and at least ten abdominal ones. In
the adult, however, many of these fuse with one another. In the
head, for example, in place of seven ganglia there are only two, one
situated above the csophagus, called the brain, and one situated
below it and called the subwsophageal ganglion. The connecting
cords are known as the circumm@sophageal commissures. The
brain is composed of three embryonic ganglia, and in the adults
of many lower insects these are still evident as three well-marked
cerebral divisions or swellings, called the protocerebrum, the deuto-
cerebrum, and the tritocerebrum. The first carries the optic lobes
and innervates the compound and simple eyes, the second bears
THE NERVOUS SYSTEM AND THE EYES. 125

two large antennal lobes, from which are given off the antennal
nerves. The third innervates the lower part of the face and the
labrum, while it gives off also a pair of nerves which unite in a small
swelling, the frontal ganglion, that lies between the pharynx and the
front of the head. A nerve runs posteriorly from this on the dorsal
side of the pharynx or cesophagus to behind the brain, where it
divides into several branches, some of which bear small ganglia while
others extend backward on the cesophagus to the stomach. These
nerves, originating in the frontal ganglion, constitute the stomato-
gastric system, sometimes called also the “ sympathetic system.”

    

{ \ / \
LmNv ~ |
\

Fig. 53.—Brain and subesophageal ganglion of worker and their principal nerves,
anterior view.

The subcesophageal ganglion consists of at most four ganglia which
innervate the mandibles, the hypopharynx, the first maxilla, and the
labium or second maxillew. In adult insects the body ganglia also
very commonly fuse with one another in varying combinations, for
the number present is always less than the number of segments, vary-
ing from eleven to one.

The brain of the bee (fig. 53, Br) is distinctly composed of two
parts, the protocerebrum (127), carrying the large optic lobes (OpL),
and the deutocerebrum (287), which consists principally of the con-
126 THE ANATOMY OF THE HONEY BEE.

spicuous antennal lobes (AntZ) that give off the large antennal
nerves (AntNv). The tritocerebrum is not present as a distinct brain
division, and its nerves, the labral (ZmNv) and the frontal (FiCom),
appear to arise from the deutocerebrum at the base of the antennal
lobes. The frontal ganglion (FtGng), formed at the union of the
two frontal nerves, gives off a very small, anterior, median nerve and
a much larger, posterior, stomatogastric trunk (StgNVv, represented
in the drawing as cut off a short distance behind the frontal ganglion)
which goes backward on the dorsal side of the pharynx beneath the
brain. Behind the latter, and just where the pharynx contracts to
the tubular esophagus, the stomatogastric nerve bears a pair of small
ganglia which are connected by short nerves with the brain, and
then it breaks up into branches that go posteriorly along the cesopha-
gus but have not been traced.

The circumcesophageal commissures are so short in the bee that
the subceesophageal ganglion appears to be attached directly to the
lower ends of the brain, while the cesophagus appears to penetrate
the latter between the antennal lobes. The three principal pairs of
nerves from the lower ganglion (J/dNv, IfxNv, and LbNv) go to the
mouth parts.

A most thorough study of the internal structure of the brain of
the bee has been made by Kenyon (1896), to whose paper the reader
is referred if interested in this subject. Kenyon’s descriptions have
never been verified, but his work has an appearance of thoroughness
and carefulness. He applies the term “ brain” to both of the nerve
masses of the head, distinguishing the upper as the “ dorsocerebrum ”
and the lower as the “ ventrocerebrum,” being led to do this from
physiological considerations, the separation of the two being merely
incidental to the passage of the esophagus.

In the thorax of the bee (figs. 1 and 52) there are two large ganglia
(1Gng and 2Gng). The first is prothoracic, being situated above
the prosternum, in front of the entosternum (fig. 52, /u,), and it
innervates the prothorax and the first pair of legs. The second,
which is situated in front of the middle legs and is protected above
by the arch of the common entosternum of the mesothorax and meta-
thorax (fig. 52, Fu.,3), is a combination of the mesothoracic and
metathoracic ganglia and the first two abdominal ganglia. This
composite structure is evident from the fact that it innervates both
the middle and the hind legs, the bases of both pairs of wings, the
mesothorax, the metathorax, the propodeum, and the first abdominal
segment behind the constriction (the true second segment). The first
and second ganglia of the abdomen (fig. 52, 3G'ng and 4G'ng) lie in
the first two segments (/7 and ///) behind the constriction, which
are the true second and third segments. But since the nerve trunks
of these ganglia go, in each case, to the segments behind them, we
THE NERVOUS SYSTEM AND THE EYES. 127

assume that they really belong to these latter segments, that is, to
segments J/J and JV. The next three ganglia (5@ng, 6Gng, and
7Gng) lie in the segments they innervate (V, VZ, and V/Z) and,
hence, belong to the fifth, sixth, and seventh abdominal segments.
The last, that is, the seventh ganglion, supplies all of the segments
behind it with nerves and is therefore probably a compound of the
ganglia originally belonging to the seventh, eighth, ninth, and tenth
segments.

In connection with the nervous system it is most convenient to
give a description of the simple and compound eyes. The other

 

Fic. 54.—Horizontal section of compound eye and optic lobe of worker (after Phillips) :
BM, basement membrane; Cor, cornea; fm, fms, fms, outer, middle, and inner fibrillar
bodies of optic lobe; inner ch, inner chiasma; Om, ommatidium; OpL, optic lobe; outer
ch, outer chiasma.

sense organs will be found already described along with the parts
on which they are located (see pp. 36 and 52). All the sense organs,
to be sure, are of ectodermal formation and are only secondarily
connected with the nervous system, but the eyes are so intimately
associated with the optic lobes of the brain that their description
here seems most appropriate.

The compound eye of the bee (figs. 9 A, 10, 52, and 53, Z’) has been
specially studied by Phillips (1905) and figures 54 and 55 are re-
produced from his drawings, while the following statements are
based on his paper: The convex outer surface or cornea of the eye
128 THE ANATOMY OF THE HONEY BEE.

presents a honeycomb appearance under the microscope, and each
little hexagonal facet is the outer end of an eye tube called an omma-

 

 

 

 

 

 

 

 

Fic. 55.—Histological details of compound cye of worker (after Phillips): A, entire
ommatidium (somewhat diagrammatic), adult; B, entire ommatidium, as if dissected
out, without outer pigment cells (diagrammatic), adult; C, section of entire om-
matidium, showing distribution of pigment, adult; D, cross section just proximal to
lens, slightly oblique; BE, cross section through extreme distal ends of retinula and
proximal ends of cones, slightly oblique; F, cross section through retinule, showing
relation of outér pigment cells in this region; G, cross section through retinule in
region of nuclei; H, cross section through retinule in region of proximal nucleus; I,
cross section of eye, cutting basement membrane parallel (the distinctness of nerve
fibers of each ommatidium is shown); BM, basement membrane; ('C, crystalline cone;
CL, crystalline lens; ¢.-p.c., corneal pigment cell; fi.c., hair-cell; Lret.n., lower retinular
nucleus; n.f., nerve fiber; Nv, nerve; o.-p.c., outer pigment cell; ret, retinula; ret.n.,
retinular nucleus; rhb, rhabdome.

tidium, all of which converge toward the internal base of the eye,
since each is vertical to the outer surface. Figure 54 is a horizontal
THE NERVOUS SYSTEM AND THE EYES. 129

section through the eye and the optic lobe of the brain. The omma-
tidia (Om) are seen converging upon tlie basement membrane (BM)
which is penetrated by the nerve fibers from the optic lobe (OpL).
The outer ends of the ommatidia are transparent, forming the
facets which together constitute the cornea (Cor) of the eye. The
nerve fibers, by a complicated course through the optic lobe, reach
the nerve cells of the brain, which are the true seat of sight percep-
tion, as of all other sensations, whether conscious or otherwise.

The ommatidia (Om), or eye tubes, are separated from one an-
other by cells containing a dark coloring matter and known as the
pigment cells. Fach tube (fig. 55 A.) consists of several parts, as fol-
lows: First, on the outside, is a clear six-sided, prismatic structure,
with convex outer and inner surfaces, called the crystalline lens (CL),
and which forms one of the facets of the cornea. Beneath the lens
is a crystalline cone (CC) having its apex directed inward and
followed by a crystalline rod or rhabdome (rhb) which extends to
the basement membrane (B./) through the middle of the omma-
tidium. (The rhabdome is represented black for the sake of distinct-
ness in figure 55 A; its natural appearance is more as shown in B
and C.) Surrounding the rod is a circle of eight or nine long re-
tinule cells (ret), each containing a conspicuous nucleus (ret. n)
above its middle and continuing basally into an optic nerve fiber (Vv)
penetrating the basement membrane. The arrangement of these
cells about the rhabdome is shown in cross section at F and G. The
inverted apex of the crystalline cone (A, B, and C, @C) is sur-
rounded by the corneal pigment cells (c.-p.c.), while the entire omma-
tidium below the lens—the base of the cone, the corneal pigment
cells, and the retinule—is surrounded by the long outer pigment
cells (0.-p. ¢.), forming a packing between all the ommatidia, as
shown in cross section at E.

The entire compound eye is simply a modified part of the epidermis
(so-called “ hypodermis ” of insect histologists) in which the cuticle
is transformed into the lenses or cornea, the cones, and the rods, the
epithelium into the pigment and retinule cells, and the basement
membrane into the floor of the eye perforated by the optic nerve fibers.
According to Phillips the ommatidia arise from the ectoderm of the
bee larva as groups of epithelial cells which become arranged in the
form of spindles surrounded by smaller cells. The cells of the
spindles become the retinule, while the surrounding small cells become
the pigment cells and the cone cells. The cone cells come to occupy
a position external to the retinule by an invagination of the latter,
and, through a transformation of most of their protoplasm into a
crystalline substance, they form the crystalline cone of the eventual
ommatidium. The approximated edges of the retinule cells are

22181—No. 18—10-—_9
130 THE ANATOMY OF THE HONEY BEE.

transformed into the crystalline rod. The cornea is secreted by the
corneal pigment cells, which at first lie distal to the cone, and possibly
also by the outer pigment cells. The nerve fibers are formed as
differentiated parts of the retinule which penetrate through the base-
ment membrane (fig. 54, Bd/) and enter the retinular ganglion be-
neath it at the outer end of the optic lobe of the brain. Hence the
retinule are simply sense end-organs of the skin comparable at an
early stage of their development with other sensory epidermal cells,
and we thus see how a simple layer of epithelium may be transformed
into such an immensely complex organ as the compound eye.

There has always been a great deal of discussion as to how insects
see by means of the compound eyes. The weight of opinion now
favors the theory that they see a part of the object or field of vision
with each ommatidium. But it is most certain that, at best, most
insects see very indistinctly, and, in fact, it is often questioned
whether they really see the shape of objects at all or not. A few of
them, however, such as dragonflies, appear to have a very acute
vision. In the case of the honey bee there is yet much difference of
opinion as to whether the workers discover nectar by the bright color
of the flowers (i. e., by the sense of sight) or by the sense of smell.
The sense of sight in bees and in insects generally, however, may be
found elaborately discussed in many books dealing with the senses of
insects.,

The simple eyes or ocelli (figs. 9 A, 10, 52, and 53, O) are con-
structed on quite a different plan from that of the compound eyes,
each consisting of a lenslike thickening of the cuticle back of which
the epithelial cells are specially elongated, and sensitized by nerve
connections. The ocelli of the bee, however, have never been care-
fully studied.

XI. THE REPRODUCTIVE SYSTEM.

The reproductive organs are those that produce the cells from
which new individuals are formed. All animals grow from at least
one cell called the egg and almost all from a combination of the egg
with another cell called a spermatozoon. The uniting of these two
cells is called the fertilization of the egg. In a few animals the two
different kinds of reproductive cells are-formed in the same individ-
ual, but in most of them, including all insects, the sperm and the eggs
are produced in different individuals—the males and the females.
In the honey bee the males are called drones, while the females are
called queens or workers, according to their functions in the hive.
The queens have the egg-producing organs or ovaries greatly devel-
oped, while these organs are rudimentary in the workers. The single
active queen in each hive, therefore, normally produces all the eggs
of the colony, while the work of rearing and providing for the brood
THE REPRODUCTIVE SYSTEM. 131

falls to the lot of the workers. Most other female insects lay their
eggs at some place where the young will be able to find food when they
hatch out, and the mother never in any way feeds or protects her
offspring; in most cases she dies before her brood emerges from the
eggs. But the wasps and bees are different in that nearly all of them
make a nest of some sort for the protection of the young larve when
they hatch, in which also they store up food for them to eat. In many
species of wild bees all the work of constructing the nest, laying the
eggs, and collecting and storing food for the young devolves upon
the single female, as it naturally should, since insects do not ordinarily
have servants, and the males of most species are utterly irresponsible
in such matters. In some of the higher wasps, such as the hornets
and yellow jackets, however, the first females that hatch out as adults
in the spring help their mother provide for a still larger family by
increasing the size of the house and collecting more provisions.
Nature designed them for this purpose, moreover, by making them
all sterile, allowing them to retain the maternal instincts, but de-
priving them of organs capable of producing offspring of their own.
Thus there is here a beginning of that division of labor which reaches
its highest development in the honey bee, where one form of the fe-
male is specialized entirely to produce the young and the other to
rear the brood, keep the home in order, gather the food, and ward
off enemies. The differences between the queens and the workers
are supposed to result from the different diet on which larve designed
to be queens ‘are brought up, but a more thorough investigation of the
food given to the different larvee of the brood is yet needed before
we can decide on the merits of this explanation. The work of numer-
ous investigators seems to have demonstrated conclusively that the
drone of the honey bee is always produced from an egg cell alone—
that is, from an unfertilized egg—while the queens and workers are
produced from fertilized eggs. The production of eggs that develop
normally without the addition of the male element is called partheno-
genesis. In a number of insects, such as some species of scales, a few
beetles, and some of the gall-forming Hymenoptera, there are no males
known, although the females are extremely abundant. Such cases
are often regarded by entomologists as examples of parthenogenesis,
and, if they are such, the result of the development of unfertilized
eggs is here the formation of females only. A few other insects, such
as some of the plant lice, produce eggs that develop without fertiliza-
tion into females or into both males and females, but such cases nearly
always occur in a cycle of alternating generations in which, at some
stage, all the eggs are fertilized. As far as is known the production
of males alone from parthenogenetic eggs is confined to the order
Hymenoptera.
132 THE ANATOMY OF THE HONEY BEE.
1. THE MALE ORGANS.

The reproductive organs of the drone are shown by figure 56 A.
They consist of the testes (Tes), the vasa deferentia (V Def), the-
vesicule seminales (Ves), the accessory or mucous glands (AcG1),
the ductus ejaculatorius (LjD), and the penis (Pen).

The testes of the bee (Tes) are said to be best developed in the pupa,
at which stage they form the spermatozoa. Each consists of a large
number of small tubules opening into a collecting reservoir at the end
of the vas deferens. The spermatozoa pass down through the coiled
vas deferens (VDef) and collect in the saclike enlargement of this
duct, which constitutes the vesicula seminalis (Ves). In the mature
adult drone these elongate sacs are densely packed with the active
spermatozoa, while the testes that produced. them become rudimentary.
The vesicule when freshly dissected appear to be alive, for they
bend and twist themselves about like small worms. Each opens by a
short duct into the base of the accessory mucous gland (AcG1) of the
same side. These organs have the form of two great sacs and are
filled with a thick, white, homogeneous, finely granular liquid, which is
supposed to mix with the spermatozoa as the latter are discharged.
The two open at the bases into the single median ejaculatory duct
(44D) which opens into the anterior end of the penis (Pen). This last
organ, shown in lateral view by figure 56 E, is an unusually large
structure in the bee and is deeply invaginated into the cavity of the
abdomen from the end of the ninth segment (D, Pen) as already de-
scribed (see page 73). While the penis is simply an ectodermal tube,
its walls present a number of very curious differentiations. The upper
part is enlarged into a bulb (fig. 56 A and E, B and PenB) having
two large irregular but symmetrical chitinous plates (¢¢) in its dorsal
wall, beneath which is a large gelatinous thickening (B, ss).
Near the base of the bulb is a double pinnate lobe (A and E, uw)
projecting from the dorsal wall. Below this, on the ventral side,
is a series of close-set, transverse plates (E, vv), followed again by
large dorsal and ventral plates (ww and wa). The terminal part
makes a thin-walled chamber (A: and E, yy), from which project
backward two very large membranous pouches (22) ending in blunt
points. The whole tube of the penis is capable of being turned
inside out, and it is said that copulation is effected by its eversion
into the oviduct of the queen, the basal pouches of the penis (22)
being forced into corresponding pouches of the oviduct, and the
spermatozoa in the bulb placed near the opening of the spermatheca
in the vagina. By their own activity probably the spermatozoa now
make their way up into this receptacle of the female, the spermatheca,
where they remain until ejected upon eggs passing down the oviduct.
The spermatozoa received from one drone normally last the queen
THE REPRODUCTIVE SYSTEM. 133

 

Fic. 56.—A, reproductive organs of drone, dorsal view, natural position ; B, inner surface
of dorsal wall of bulb of penis (EH, PenB), showing gelatinous thickening (ss); C,
group of spermatozoa and intermixed granules; D, terminal segments of male abdomen,
showing the seventh tergum (VIIT) removed from its sternum (VI7S) and the penis
(Pen) partly protruded; B, lateral view of penis as invaginated within abdomen, and

ejaculatory duct (£jD).
134 THE ANATOMY OF THE HONEY BEE.

throughout her life, so that after mating she goes into the hive never
again to emerge except with a swarm, and her entire life is devoted
to egg laying. The drone, on the other hand, dies immediately after
mating, while those that do not mate are driven out of the hive in
the fall and left to starve.

The spermatozoa (fig. 56 C) are minute threadlike cells, capable of
a vibratory motion. As found in the vesicule, they are usually bent
into closely compressed loops, although many are extended to their
entire length. One end is blunt, but not noticeably enlarged, the
other is tapering, while the half toward the tapering end seems to
be the part chiefly endowed with the power of motion. The sperm
threads are contained in a liquid within the vesicule, in which float
also a great number of minute granules. The vibrations of the
spermatozoa keep these granules in constant motion.

2. THE FEMALE ORGANS,

The organs of the female that produce the eggs are called the
ovaries (fig. 57, Ov). In insects they consist of a varying number of
egg tubules or ovarioles (ov) forming two lateral groups, in each of
which the tubules converge at both ends, the anterior ends being
drawn out into fine threads whose tips are connected, while the poste-
rior ends are widened and open into the anterior end of the oviduct
(OvD) on the same side of the body. An egg is simply a very large
cell whose size is due to the great accumulation of yolk in its proto-
plasm, which serves as food for the future embryo. The eggs are
formed in the terminal threads of the ovarioles and are at first appar-
ently ordinary undifferentiated cells, but as they pass downward’ in
the tubule they increase in size at the expense of some of the other
ovarian cells, Hence the ovarioles usually have the form of a string
of beads arranged in a graded series from very tiny ones at the upper
end to others the size of the mature egg at the lower end. The two
oviducts converge posteriorly and unite into the common median duct
or vagina (Vag) which in most insects opens to the exterior upon
the eighth sternum, as already described in the general account of the
external anatomy of insects (see page 25), but in the bee and many
other insects the eighth sternum is entirely lacking as a distinct
sclerite, and the genital opening is therefore behind the seventh ster-
num and below the base of the sting. The posterior part of the
vagina is very large, forming a bursa copulatria (BCpx). In addi-
tion to these parts there is nearly always present in insects a special
receptacle for the spermatozoa called the spermatheca (Spm). This,
in most insects, opens directly into the vagina as it does in the bee, but
in some it opens into the roof of the genital chamber above the eighth
sternum, when this is present, by a separate orifice behind that of the
THE REPRODUCTIVE SYSTEM. 135

 

Fig. 57.—Reproductive ‘organs, sting, and poison glands of queen, dorsal view.
136 THE ANATOMY OF THE HONEY BEE.

vagina. In the bee the two poison glands (AGI and BG/) do not
open into the vagina but, as already described, into the base of the
sting. They are, hence, ‘probably special ongans having no homo-
logues in nonstinging insects.

The ovaries of the queen bee form two large gourd-shaped masses
(fig. 57, Ov) whose posterior or basal ends are enlarged and whose
anterior ends are narrowed, curved,.and attached to each other.
Since the queen lays eggs continuously during her entire life the
ovaries always contain eggs in all stages of growth, and conse-
quently do not vary so much in appearance as they do in those insects
that ripen only one lot of eggs and deposit these all at. one time.

The structure of the ovarioles and the formation of the eggs in the bee
have been specially studied by Paulcke (1900) and the following is
a résumé of his paper: The terminal threads of the ovarioles are
covered by a thin tunica propria and are filled with a protoplasmic
mass containing transversely elongate nuclei in a single close series,
but no cell outlines.. Farther down, in the upper end of the ovariole
proper, the nuclei become arranged in two rows, while here also the
cell boundaries begin to appear; still farther along, where the cells
are clearly defined, the latter become differentiated into epithelial
cells and germ cells. Next, the germ cells themselves divide into
egg cells and food or nurse cells. When first formed the egg cells
occur in any part,of the diameter of the tube, but they soon become
arranged in a row down the middle of the ovariole and are separated
by groups of nurse cells. The epithelial cells at this time arrange
themselves on the periphery just within the tunica propria, but
farther down they form a capsule or follicle about the egg and, less
definitely, about the group of nurse cells at its upper end. The upper
end of the egg becomes narrowed by a constriction of the epithelial
capsule, which, however, does not shut it off from the nurse cells,
a connection being retained with the latter in the form of a neck
from the egg abutting against them. There are 48 of these nurse
cells to each egg, which fact is accounted for by supposing that each
original germ cell divides into 4, one of which ceases further divi-
sion and becomes the egg cell, while each of the other 3 divides into
16 by four consecutive divisions. The latter are the nurse cells and
their function is ‘to nourish the egg cells. They persist down to
the time when the egg is fully formed, when they suddenly disappear
by being absorbed bodily into its yolk. Toward the end of the
growth of the egg the follicle cells become thinner and thinner, so
that when the egg is ready to go into the oviduct it has but a thin
membrane to break through.

The organs of most especial interest to the student of the bee are the
spermatheca and the apparatus by means of which the queen is able
to dole out the spermatozoa to the eggs as she deposits the latter.
THE REPRODUCTIVE SYSTEM. 187

The spermatheca consists of a globular seminal sac (fig. 57, Spm),
of a pair of tubular accessory glands (SpmG@l), and of a duct whose
upper end is connected with the sac and receives also the duct of the
glands, and whose lower end opens into the anterior part of the
dorsal wall of the vagina just caudad of the united bases of the
oviducts.

The spermatozoa are discharged by the male into the upper end
of the vagina, and in some manner they make their way up into the
sperm sac through the duct. Cheshire (1885) described the latter
as forking toward its lower end into an anterior branch which opens
into the vagina and into a posterior branch which turns backward
and becomes lost in the lower end of the vaginal wall. This second
branch he believes is open in the young queen and is the one through
which the spermatozoa enter the sac. Breslau (1906) has shown, how-
ever, that Cheshire was entirely wrong in his supposed observation
of the forking of the duct, that the latter is a single tube, and that
consequently the spermatozoa must both enter and leave the sac by the
same conduit. It used to be supposed that the sperm sac had muscular
walls and that it forced the spermatozoa out as from a compressed
bulb, but Breslau has shown that this also is a mistaken notion, that
the walls of the sac are entirely devoid of muscular fibers, and that
the spermatozoa are sucked out by a muscular apparatus in the wall of
the duct, which structure he names the sperm pump. Cheshire (1885)
had previously described this apparatus in a very imperfect manner
without recognizing any pumping function, for he supposed that
by the relaxation of certain muscles the spermatozoa simply passed out
of the sac and went down the tube. Breslau says, however, that
the spermatozoa have not enough energy of their own to come out of
the sac and, hence, do not need to be kept in by a special sphintter
muscle, as described by Leydig.

The upper end of the spermathecal duct makes an S-shaped bend
just beyond the opening of the sac, and a number of muscles dis-
posed upon this part constitute Breslau’s sperm-pump. Breslau shows
that’ a contraction of certain of these muscles flattens the bend of
the S and causes an enlargement of the lumen of the upper end of
the loop. This, therefore, sucks into itself a small bundle of sperma-
tozoa from the sac. The contraction then of other muscles forces
the rest of the sperm-threads back into the mouth of the sac and
drives the small bundlé thus cut. off down through the duct and into
the vagina. Moreover, Breslau claims that this explanation is not
theory only, for, by preparing histological sections from queens
killed at different moments of egg-laying, he procured specimens
showing the various stages in the pumping process and in the passage
of the sperm through the duct. Cheshire calculated that a normal
queen lays 1,500,000 eggs in her lifetime and that the spermatheca
188 THE ANATOMY OF THE HONEY BEE.

holds about 4,000,000 spermatozoa, and therefore, allowing for drones,
he concludes that there can not be more than four sperm-threads given
to each female egg. But Breslau, figuring from the size of the sperm-
bundle taken into the duct, for each egg, states that each egg is
actually given 75 to 100 spermatozoa. We feel that the latter calcula-
tion must be much more reliable than that of Cheshire because it
is based on an actual observation of the size of the sperm mass de-
livered to the egg. Moreover, the myriads and myriads of tiny
spermatozoa contained in the spermathecal sac make any attempt
at a calculation of the number look absurd, and we can not believe
that it is possible to even approximate the number present. Fur-
thermore, as Breslau states, 100 spermatozoa make such an excessively
small bundle that it requires a most effective and perfect apparatus to
deliver even this number with anything like exactness—it is incon-
ceivable that a mechanism could be perfect enough to give out only
4 or 5 or even 7 at a time.

On the floor of the vagina, opposite the opening of the spermathecal
duct, is a free flap provided with muscles, which is so situated
that when elevated its end fits into the opening of the duct above.
Leuckart (1858) explained this flap as a contrivance for holding the
passing egg tight against the upper vaginal wall so that its aperture
through which the spermatozoa is received, called the micropyle, would
come against the opening of the duct and thus insure fertilization.
Breslau, on the other hand, does not think the fiap in question has
any such function and he regards it as a valve which by fitting into
the orifice of the spermathecal duct closes the latter and so prevents
the pump from sucking up the contents of the vagina at the same time
that it sucks a bundle of spermatozoa out of the sac. Since, however,
the flap is on the floor of the vagina and is pressed down by the passing
egg it is not clear how it can at such a time act as a valve to close the
orifice of the duct in the dorsal wall, since the pump is supposed to
work by reflex action as the egg is entering the vagina, though, of
course, it may so function before the egg has gone far enough to
intervene between it and the duct opening; but it would certainly
seem that a valve to close the latter, if needed at all, would be de-
veloped in the dorsal wall of the vagina in connection with the orifice
itself. Furthermore, a collapsible tube like the spermathecal duct,
even though lined with chitin, should automatically close at its
lower end when a suction force is applied at the upper end.

Finally, Breslau attributes to the sperm pump not only the func-
tion of delivering a definite mass of spermatozoa to each egg, but also
that of sucking the spermatozoa up from the vagina of a newly fer-
tilized queen into the spermathecal sac. He does not seem now to see
in the valve any obstacle to such an action. The spermatozoa are
usually supposed to make their way up the duct by their own vibra-
tory motion.
EXPLANATION OF SYMBOLS AND LETTERS. 139

The anatomy of the spermatheca and the muscular apparatus of its
duct for delivering the spermatozoa to the egg does not, as Breslau
points out, throw any light on the determination of sex in bees. It isa
common notion that all eggs of an unfertilized female develop into
drones, but this is by no means proved; in fact, there is just as good
reason for believing that, while no females develop, there are also no
more than the normal number of drones produced—the eggs that
might otherwise have developed into females, if laid by a fertile queen,
all dying in the cells of the comb, from which they are removed by the
workers. Modern investigation of the determination of sex shows that
there is probably just as much reason in many cases for supposing that
sex is established in the egg of the ovary before fertilization, as there
is for believing it to result from fertilization or from subsequent en-
vironment of the egg or young embryo. Hence, it is not only very.
doubtful that the queen determines the sex of her offspring by con-
trolling the fertilization of the eggs, but it is also very uncertain that
fertilization itself has anything to do with it. Parthenogenesis in
the bee may amount simply to this, that the male eggs, predetermined
as such in the ovary, are capable of developing without fertilization,
while the female eggs are incapable of such a development and die if
they are not fertilized.

Each unlaid egg of insects in general has a small hole in the upper
end of its shell, called the micropyle, which admits the spermatozoa to
its interior. One or several spermatozoa may enter the egg through
this aperture, but the nuclear part of only one unites with the egg
nucleus, this constituting the fertilization of the egg. After this the
micropyle closes and the egg is deposited in a cell of the comb by the
queen. The nucleus and a part of the protoplasm of the egg then
begin to split up into a number of small cells which—but this is
taking us into the development of the next generation, which is
beyond the limits of our subject, and so here we must stop.

EXPLANATION. OF THE SYMBOLS AND LETTERS USED ON THE
ILLUSTRATIONS,

The writer has made an attempt to work out a set of convenient
symbols for all the principal external and internal parts in the anat-
omy of an insect. It has been found, however, that entire consistency
is incompatible with practicability, especially in making compound
abbreviations, and, therefore, the latter has been given first considera-
tion in many cases. For example, the symbol Dect suggests the word
“duct ” when standing alone much better than simply the letter D,
but such combinations as SalDct and OvDct are unnecessarily long
and the shortened forms of SalD and OvD are sufficiently suggestive
of “salivary duct” and “ oviduct.” The abbreviation Se is used
in such compound symbols as PsnSc for “ poison sac” and T'raSc
140 THE ANATOMY OF THE HONEY BEE.

for “ tracheal sac,” notwithstanding that Sc alone means “ subcosta.”
The symbol 7’ is used for “tergum,” and 7,, 7., ete., and /7, IT,
etc., indicate individual thoracic and abdominal terga, but 7'Mfcl is
used to signify “ transverse muscle.” And so, in several other cases,
it has been found expedient to sacrifice strict uniformity to practical
considerations.

A combination of lower-case letters duplicating one entirely or
partly of capitals signifies that the part so designated is a part or sub-
division of the other. For example, Zen refers to the principal part
of the tentorium and ¢en to a minor part; Pl and pi are subdivisions
of the same pleurum; Zmel and Ime are both longitudinal muscles.

The most logical method of referring symbols to any particular
segment of the body would be, perhaps, to prefix them with either a
Roman or an Arabic numeral corresponding with the number of the
segment. A common objection, however, to both would arise from
the fact that entomologists are not at all agreed as to how many seg-
ments there are in any region of an insect’s body. Furthermore,
Roman numerals prefixed to all the symbols necessarily used on a
drawing of the thorax, for example, would occupy entirely too much
space. Finally, it is very desirable to have a method of referring to
repeated structures without implying any segmental connection, and
prefixed Arabic numerals are certainly most convenient and sug-
gestive for such a purpose. A system often adopted to indicate the
segment to which a part belongs, especially in the thorax,.is the use
of one, two, or three accents in connection with the abbreviation.
But accented symbols lack artistic unity, and some of the accent
marks are too easily lost in the engraving and printing. For these
several reasons the writer has adopted the following system:

Numerical order of any repeated structure is indicated by an
Arabic numeral placed before the abbreviation, and has no segmental
significance. Thus 7P, 2P, etc., mean simply “ first parapterum,”
“second parapterum,” ete; 1@ng, 2Gng, etc., mean “ first ganglion,”
“second ganglion,” etc., without implying that the ganglion belongs
to any particular segment.

Symbols are referred to the prothorax, the mesothorax, or the meta-
thorax, respectively, by the figures 1, 2, and 3 placed below and
after them, except on the wings, where re numbers designate the
branches of the veins according to the Comstock-Needham system.

The abdominal segments, counting the propodeum as the first, are
indicated by the Roman numerals J to X, and, when any one of these
is placed before an abbreviation, it refers the symbol to that indi-
vidual segment.

The lower-case letters are used, singly and in pairs, to refer to
miscellaneous parts having, in most cases, no individual or general
anatomical names.
A,
AcGl,
AGI,
AGID,
An,
ANP,
ANR,
Ant,
AntL,
AntNv,
Ao,
Ap,
Aph,
Ag,

an,
Aad,

AgM,

BO,
be,

BCpe,
BGl,
BM,

1IBr,
2Br,
3Br,
Bro,
BW,
¢,
Cb,
ce,
Cd,
Cer,
CL,
Cl, Cls,
Cla,
Clip,
Clsp,

1Clsp,
2Clsp,
Com,
Cor,
Ctl,
Cu,

EXPLANATION OF SYMBOLS AND LETTERS. 141

1. SYMBOLS.

anal vein; 7A, first anal, 2.1, second anal, etc.

accessory gland of male reproductive organs.

acid gland of sting, opening into poison sac (PsnNc).

duct of acid gland of sting.

anus.

anterior wing process of notum.

anterior marginal ridge of notum.

antenna.

antennal lobe of brain.

antennal nerve.

aorta.

apodeme, any internal chitinous process of body-wall.

anterior phragma of any tergum, prephragma.

the axillaries or articular sclerites of the wing base, designated
individually as 1Az, 2Ax, 3Ax”, and 4Ar.

accessory axillary sclerites of irregular occurrence in connection
with the principal axillaries (Av).

axillary cord, or ligament-like thickening of posterior edge of basal
membrane of wing, attached to posterior angle of scutellum.

axillary membrane, the thin membrane of wing base, containing
the axillary sclerites and forming in some cases the lobes called
alule.

bulb (bulb of penis or of sheath of sting).

body-cavity.

any particular part of body cavity such as that prolonged into the
mouth parts, legs or pieces of the sting.

bursa copulatrix. ;

alkaline gland of sting.

basement membrane.

brain.

protocerebrum.

deutocerebrum.

tritocerebrum.

barb.

body-wall. :

costa, first vein of wing.

pollen basket or corbiculum on hind tibia of worker.

erystalline cone of compound eye.

cardo.

eercus.

crystalline lens of compound eye.

cell, cells.

claw.

clypeus.

clasping lobes of ninth segment of male, perhaps equivalent to the
four gonapophyses of ninth segment of female.

upper or outer clasper.

lower or inner clasper.

commissure (of either nervous or tracheal system).

cornea.

cuticle, the chitinous layer of the epidermis.

cubitus, fifth vein of generalized wing.
142

Cv,

Ca,

CrP,
Det,
DDph,
Dph,
DphCls,
Dphmod,
DphMel,
H,
EAp,
EjD,
Em,
EMcl,
Emp,
Enz,
Ep,
Ephy,
Epm,
Eps,
Epth,
F,
Fil,
For,
Ft,
Ftdom,
FtGng,
FtNnv,
Fu,

G,

Ga,

Ge,

Gl,

1G1,
2Gl,
8Gl,
4G,
Gls,
Gng,
Gu,

A,

Hk,
Hphy,
Ar,

hr,

HS,

Ht,

ht,

HtCls,
HtTraSc,
Int,

IT,

THE ANATOMY OF THE HONEY BEE.

cross-vein.

coxa.

pleural coxal process.

duct.

dorsal diaphragm.

diaphragm.

diaphragm cells.

membrane of diaphragm.

iuuscle fibers of diaphragm.

compound eye.

apodeme of extensor muscle.

ejaculatory duct.

lateral emargination of notum.

extensor muscle.

empodium.

digestive vesicles formed by ventricular epithelium.

epicranium.

epipharynx.

epimerum.

cpisternum.

epithelium.

femur.

flagellum.

foramen magnum.

front.

frontal commissure,

frontal ganglion.

frontal nerve.

furca or median entosternal apodeme of thoracic sterna.

gonapophysis.

galea.

gena.

gland.

large pharyngeal gland in anterior part of head of worker.

salivary gland in posterior part of head.

thoracic salivary gland.

small median gland below pharyngeal plate (s).

glossa.

ganglion.

gula.

head.

hooks on front edge of hind wing.

hypopharynx.

hair.

surface disk of “auditory” organ of antenna, probably modified
base of sensory hair.

honey stomach.

heart.

individual chamber of heart.

pericardial cells.

pericardial, tracheal sac.

intima, the chitinous lining of any internal organ.

tergum of first abdominal segment, the median segment, or pro-
podeum, incorporated into thorax.
D,

Db,
Lol,
LoNnv,
LbPlp,
Le,
Let,
Lg,
LG,
Lin,
Im,
LMcel,
imel,
LmN»v,
Lr,
LTra,
Lum,

M,
m,
Val,
Mod,

mob,
m-cu,

Com,

OpL,

EXPLANATION OF SYMBOLS AND LETTERS. 143

leg.

Jabium.
labellum.
labial nerve.
labial palpus.

lacinia.
lancet of sting, equivalent to first gonapophysis (1G).
ligula. °

“lubricating ” gland of sting (not shown in figures).

median lobe of lingua or hypopharynx.

Jabrum.

longitudinal muscles.

ventral longitudinal muscles of thorax.

labral nerve.

Jorum.

trachea of leg.

lumen, the cavity of any hollow organ, whether the glossa, sting,
alimentary canal, or gland.

media, fourth vein of wing. M,—-J,, first to fourth branches of
media.

median plate or plates of wing base.

Malpighian tubules.

intersegmental membrane.

membrane.

medio-cubital cross-vein.

disclike muscle apodeme.

mandible.

outer saclike mandibular gland.

inner racemose mandibular gland.

mandibular nerve.

mesothorax, designated by figure 2 placed after and below any
thoracic symbol.

metathorax, designated by figure 3 placed after and below any
thoracic symbol.

the chitinous plates of the neck collectively, the ‘ microthorax,”
individually designated mi.

cervical (microthoracic) sclerites.

median cross-vein.

mouth parts or trophi.

mentum.

mouth.

maxilla.

maxillary palpus.

maxillary nerve.

notum.

nucleus.

nerve.

ocellus,

oblong plate.

occiput.

cesophagus.

circumcesophageal commissures.

ommatidium.

optic lobe.

-
144

Ost,
Ov,
Ov,
OvD,
ovo,”

1P, 2P,
3P, 4P,
PA,
Pel,
PD,

Pd,
Pen,
PenB,
Peps,
Pge,
Pgl,
Pgu,
Ph,
Phy,
Pl,

pl,
Pif,
Pig,
Pip,
Pmbd,
‘PUcl,
PN,

pn,

PNP,
PNR,
Pph,

PR,

Prob,
ProFs,
PS,

Pse,
Pscl,
Psi,
Psne,
PsnSc,

THE ANATOMY OF THE HONEY BEE.

ostium or lateral aperture of heart.

ovary.

ovariole, individual ovarian tube.

oviduct.

opening of vagina or median oviduct.

paraptera, small pleural plates below base of wing, typically two
episternal paraptera or preparaptera (1P and 2P)before pleural
wing process (WP), and two epimeral paraptera or postparap-
tera (8P and 4P) behind wing process.

episternal paraptera, preparaptera.

epimeral paraptera, postparaptera.

arm of pleural ridge.

postclypeus.

muscle disc of episternal paraptera, giving insertion to pronator
muscle (not present in the bee).

peduncle.

penis.

bulb of penis.

preepisternum.

postgena.

paraglossa.

pregula.

phragma.

pharnyx.

pleurum.

subdivision of pleurum.

palpifer, palpus-carrying lobe of maxilla.

palpiger, palpus-carrying lobe of labium.

palpus.

peritrophic membrane.

pronator muscle.

postnotum or pseudonotum, the second or postalar tergal plate of
the wing-bearing segments of most insects, the “ postscutellum ”
of higher orders.

small rod connecting postscutellum (postnotum PN) with upper
edge of epimerum, probably a detached piece of the former (see
figs. 22 and 24).

posterior notal wing process.

posterior marginal ridge of notum.

posterior phragma or postphragma of any tergum, carried by the
second notal plate or postnotum (PV), the “ postscutellum ” of
higher forms.

internal pleural ridge, the entopleurum, marked externally by
pleural suture (PS).

proboscis. :

fossa of proboscis.

pleural suture, external line separating episternum and epimerum,
marking site of internal pleural ridge.

presternum.

prescutum.

postscutellum (postnotum).

poststernellum.

poison canal of sting.

poison sac of sting into which opens the acid gland (AGl).
Pt,

Ptr,
Pvent,
Pvent Viv,
Qd, *
R,

RAp,
Rad,

Rect,
RG,
rm,
Rilcl,
IRMel,
2RMel,
Rs,

8,
SalD,
SalDoO,
Se,
Sol,
Sep,
Sct,
Sga,
Sh,

ShA,
SAB,
SRS,
SInt,
Sl,

Slin,

Smt,
SeGng,
Sp,
Spm,
SpmGi,
St,
StgNv,
Stn,
StnPlp,

T,
IT,
IIT,
Tar,
Tb,
Ten,
ten,
Tes,
T9,

EXPLANATION OF SYMBOLS AND LETTERS. 145

sensory pit.

peritreme, spiracle-bearing sclerite.

proventriculus. =

proventricular tube or valve in ventriculus.

quadrate plate of sting.

radius, third vein of generalized wing. R.-R,, first to fifth branches
of radius. Rs, radial sector.

apodeme of flexor muscle.

posterior extension or reduplication of any tergal or sternal plate
overlapping plate following it.

rectum, the large intestine of insects.

rectal glands.

radio-medial cross-vein.

flexor muscle of mandible or wing.

dorsal retractor muscle of ligula.

ventral retractor muscle of ligula.

radial sector, or second branch of radius at first forking.

sternum.

salivary duct.

external opening of salivary duct.

subcosta, second vein of generalized wing.

scutellum.

scape.

scutum.

subgalea.

sheath of sting, equivalent to the second gonapophyses (2G) or
caiddle pair on ninth abdominal segment.

Lasal arm of sheath of sting.

bulb of sheath of sting or ovipositor.

shaft of sheath of sting.

Small intestine.

sternellum.

superlingua, embryonic lateral lobes of hypopharynx, true append-
ages of fifth head segment.

submentum,

subcesophageal ganglion.

spiracle.

spermatheca.

spermathecal gland.

stipes.

stomatogastric nerve.

sting.

palpuslike appendages of the sting, equivalent to the third gona-
popbyses (3G) or the outer pair on ninth abdominal segment.

tergum. :

first abdominal tergum, the propodeum, incorporated into thorax.

second abdominal tergum.

tarsus.

tibia.

large tentorial arms of head, the mesocephalic pillars.

slender tentorial arch over foramen magnum,

testes.

tegula.

22181—No, 18—10-——_10
146

TMel,
Tn,
Tne,
Tr,
Tra,
TraCom,
TraSe,
Tri,
Vag,
VDef,
VDph,
Vent,
VentVla,
Ves,
Viv,
VMel,
VNR,
Va,
W,
W,Nv,
W.Nv,

3
WP,

VY

W,

THE ANATOMY OF THE HONEY BEE.

transverse muscle.

trochantin (not separated from sternum in bee).
coxal condyle of trochantin.

trochanter.

trachea.

transverse ventral tracheal commissures of abdomen.
tracheal sac.

triangular plate of sting.

vagina.

yas deferens.

ventral diaphragm.

ventriculus.

ventricular fold or valve in small intestine.
vesicula seminalis.

valve of sting carried by lancet.

large vertical muscles of thorax. :
internal, median V-shaped notal ridge, the ‘“ entodorsum.”
vertex.

wing.

mesothoracic wing nerve.

metathoracic wing nerve.

wing process of pleurum.

2. ALPHABETICAL LETTERING.

elypeal suture.

anterior tentorial pit, in clypeal suture.

posterior tentorial pit, in occiput beside foramen magnum.

thickened posterior edge cf lateral wall of fossa of proboscis.

process at upper end of d articulating with cardo of maxilla and
forming maxillary suspensorium.

internal median keel of vertex in cranium of drone.

suspensorial ligaments of anterior end of cesophagus.

pharyngeal rod.

convolutions of dorsal blood vessel.

anterior articular knob of mandible.

ventral groove of glossa.

ventral groove of maxillary rod.

median plates of wing base.

basal hooks of glossa.

median ventral plate of ligula.

dorsal plates of anterior end of mentum, supporting ligula.

inner ‘wall of canal of glossa.

chitinous rod of glossa.

pharyngeal plate, on anterior part of floor of pharynx.

salivary pouch opening on dorsal side of base of ligula, receiving
common duct of salivary glands (SalD).

oblique muscles inserted upon dorsal side of salivary pouch of
ligula.

transverse or V-shaped suture on surface of mesonotum or metano-
tum, formed by the internal V-shaped ridge or ‘‘entodorsum ”
(TNR).

lateral lobe of pronotum projecting posteriorly over the first
spiracle,
@,

y
&,

aa,

bb,

ce,

dd,
ee,
Ff,
99;
hh,
i,
ji,

kk,

ul,
mm,

nn,

00,

DD,

qq;
TY,

8s,

tt~,
wu,
vv,
ww,
Le,
UY;
22,

EXPLANATION OF SYMBOLS AND LETTERS. 147

thoracic plate lying laterad of anterior part of sternum, often
regarded as a part of presternum.

accessory sclerite of fourth axillary (447) of front wing, affording
insertion for slender muscle (fig. 28, ec) attached below to
common apodeme of mesosternum and metasternum.

coxal condyles of mesothoracic and metathoracic sterna, probably
really the coxal condyles of trochantins (fig. 4, 7nC@) fused en-
tirely with the sterna and episterna in each segment.

muscle arising from inner wall of mesothoracic pleurum and in-
serted upon outer end of corresponding scutellum, probably ac-
cessory in function to the great vertical muscles (fig. 27, Vict)
between the mesothoracic sternum and scutum.

coxo-axillary muscle, extending from upper end of coxa to third
parapterum (8P).

muscle inserted upon accessory sclerite (y) of fourth axillary
(44@) from common gntosternum of mesothorax and meta-
thorax.

notch of antenna cleaner on first tarsal joint (17 ar) of front leg.

spine of antenna cleaner situated on distal end of tibia (Tb).

so-called “ wax shears” or “ wax pincers.”

transverse chitinous band of empodium (Hmp), which compresses
its two lobes when not in use and spread out by muscular effort.

dorsal plate supporting empodium.

ventral plate supporting empodium.

dorsal groove of lancet interlocking with ventral ridge of sheath of
sting.

sting chamber within end of seventh abdominal segment, lodging
sting whose accessory plates are derived from eighth and ninth
segments,

reservoir of thoracic salivary gland.

receptacular chitinous pouches on ventral side of pharyngeal plate
(s) receiving ducts of large lateral pharyngeal glands of head
(141).

“stomach-mouth” at summit of proventricular projection within
honey stomach (HS).

pores on lancets (fig. 40 E) and shaft of sting sheath (F) open-
ing to exterior from prolongation of body-cavity (bc) contained
in each.

gelatinous layer secreted upon inner surface of ventricular epi-
thelium. .

food contents of alimentary canal.

cells of ventricular epithelium apparently forming the internal
gelatinous layer.

cartilaginous mass on inner surface of dorsal wall of bulb of
penis (fig. 56 E, PenB).

dorsal plates of bulb of penis.

fimbriated dorsal lobes of penis at base of bulb.

ventral scalariform row of plates on tube of penis.

dorsal basal plates of penis.

ventral basal plates of penis.

basal pouch of penis.

copulatory sacs of penis.
148 THE ANATOMY OF THE HONEY BEE.
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Scumip, A., and KLEINE, G.
1861. Umrisse zur Anatomie und Physiologie der Bienen. Die Bienen-
zeitung, I, pp. 498-525, pls. I-VITI.

ScuG6NFELD, Pastor.
1886. Die physiologische Bedeutung des Magenmundes der H6nigbiene.
Arch. f. Anat. und Physiol., Physiol. Abth., pp. 451-458.
SLapen, F. W. L.
' 1901. A scent-producing organ in the abdomen of the bee. Gleanings in
Bee Culture, XXIX, August, pp. 639, 640, 1 fig.
1902. A scent-producing organ in the abdomen of the worker of Apis
mellifica. Ent. Mag. Lond., XX XVIII, pp. 208-211, 1 fig.

Wo rr, O. J. B.
1875. Das Riechorgan der Biene. Nova Acta der Ks]. Leop.-Carol. Deut.
Akad. der Naturf., XX XVIII, pp. 1-251, pls. I-VIII.
ZANDER, ENOCH.
1899. Beitriige zur Morphologie des Stachelapparates der Hymenopteren. -
Zeit. f. wiss. Zool., LXVI, pp. 288-333, pls. XVIII, XIX.
1900. Beitriige zur Morphologie der minnlichen Geschlichtsorgiine der
Hymenopteren. Zeit. f. wiss. Zool. LXVII, pp. 461-489, 9 figs.,
pl, XXVII,
Page.
Abdomen, defined. ..........22..-0.222.002 222 e eee eee cece e eee ence 13-14
general structure. ...........22.-2.-22 200-2 e eee eee eee eee eee eee 24-26
OPNOHEVADEG oo nie aa taeanesd Saw ee a Roe eee 69-71
MUSCLES, « <sce-sese aisle a wlalaisl sRetevanei decree wreieiscets a ag wees 118-119
wax glands and sting..............------------------ 69-83
ANDSOLP tM si satettoteletalitetie 2 ee e ole Siateidnig's' bie oes ee eteuns Get lated ielaele caves 104-105
Accessory sternal plate in generalized thorax.........-.-----------++---++---- 21
Acid.gland of sting’... 2c-nsvese ys ees o<'s ¥aass eeeeeuseant see sae vais e 79
Alimentary canal snceemecev\ esse ses ss sass eed eteeeueesectecowaeeee ss 90
andats: lands. i20% wv 442e sean nearenee eden ene pe ess 84-106
Alkaline gland of stings... ssevsss esses is5 sa vacneeneieeseecesstases es es 79
Anabolism ....-..-.- eit Tye eee ee eS e ie ae yak Anis Sy aie ad leech aren ramen a 86
Anal veins of generalized wing..........--.-2.---2- 22-202 ee eee eee eee eee eee 22
Hymenoptera. . ....-2+s¢sse:eeeeseeeus newness ANAS OMA 59
Andrena, pharyngeal glands. ........-.-.2.-2-2-2--2-2-0-222-0-- esi aeseenee 92
Anteclypeusicccccecexecmover vues ete uxceinees See 54 s eae Ghuahe cesses 15
Antenna, cleanel:: 22s¢e:ec1cededaeeneass levee ey sei 5 oo ce snus sucaca dae deeaka 66
Antenne and their sense organs... .......2-2--2--2---222-0-22 eee eee eee eee 32-39
defined. eizewmy see's sss Se seed ee Sl aesdace Padsstsindaeoeeeea cgaiale 16
of honey bee. .........----.-- saebigeieagieeag elena med oreo peteialate 27, 32-33
BCMSENOLP ANG 2 eee evel aes 62 Gt eielemialtte 36-39
Anténnal lobess:cceseseee vee vee se voenss oor Us 27522508 oon Ronee eeGiewaliels ss 125
Anterior notal wing process, defined.............2..2...2202220ce eee eee eee 19
of mesothorax of honey bee...........-------.-- 62
metathorax of honey bee...................-. 56
Anthophora, pharyngeal glands... ....-...--.-2.0202222-0-2e eee eee eee eee 92
ANUS sys ereesecs Bank .cccaickianeiaiia ini Sine Seee6ensedeeaccsemeueereaen 78
INOUE caifrere te eteeiassecisec cad aie MINS LhwemMee ee Atee ee aeAaa ae iaw nese sase 108-109
APO OMEB 5 sie case hea one een ehiGuasen oles Matte ces ential See ee oats 32
79) 91-310 124-5 eee ae ee ee ee 12-13
PASBIDAN A OM Ses (ADGA Ae EUR RES a eean tyr nL Ol na pn aA Rta pate 84-87
Ascillaries defined sc acisacysaiennn ceceaecaniaeeee oes oe one eese LEON 23
of front wing of honey bee............--2.02.2-2-2--200---- axils 62
hind wing of honey bee........22.-.2.22-.2-0.22-222eeeeeeee 62
Hy MenOptera ne cicccccammencccsesreaueaias ss eeeecesegesanwena 59-62
Axillary cord, defined. ... 2... 200.2 lle eee ee 19
of generalized Wilt. s2c0cic0sccesccelscig ue de ey etuiieascni 23
HONCY bOCs cccac:camecs sav etyseilGaiie pee dees edd 4 oeueucus 62
membrane of generalized wing.......-....2.-.02.02.0.000--2 eee ee 23
HONG Y"D6Ox 22 ssrtiranenr weearien weld Ao ie oes aoe ae 61

Basal ligament of wing. (See Axillary cord.)
Basement MEMbTANE . cee ae oases Mase geune darseeseeusese diy ee vdaee. oedewmues 129
Blatta, development of head........... 22. ..0.0 000.0202 c eee ec eee eee eee eee 18
1000 crate naanewapesassoecoerec meee sy ete dt cumeee dd cle eee naoeneleenbagan 107
Body wall oc. . ses sassedcoeig anaese seu svet seeeedawccnn sen uewaxdestoeedes 14-15
152 THE ANATOMY OF THE HONEY BEE,

Page.

Bombus, pharyngeal glands. .......-.-. 2222.00.22 2 cece cece cece cece ceeeeees 92
ROUGE col ied ose, caged Soc edacpemr eee eueae Sia raed ate oeaa aseat See eece arress caehcas 45
Brain, general description. ..-......2-.--.-.2 020020 c eee e nce c eee eee ee ee eeee 124
ORhone y bee cecne sess se tata awash 2 ie sae deed etecstan 2 bree ee 125-126

Brood 100d voce Sa aceic cokes teas scence epoisieisfas! ev oee wapeseacemeeee sus ceeattae 92-94
production of, and summary of facts known concerning it ........- 98-101

Bursa copulatrix.........2...-2.-++--- Sole Sistniden ss Bd Hee Noein we eye i ee cielt 134
Carbohydrates :itwasce: c.chiu co's 6 cadena sede eee eeamaamed Hadsisa oe S0eaG aes 89
CardG,;deAned Yas sosscccseiwne jee Seeds SUE oHd ws SAUER ESE oat 17
OLNONEY eC: sai sccunt te nic teen aeadates nic oMarieeae ee lee eed 45

Cells of body, defined............2.. 22222-0202 c cece eee ee cee eee eee eee eee 84-86
WANG, CANO wr reie ci teiles oa fas snsicistee ettete stelle eee stays seein ain see eae 23

Cerci; defined ic jsctnsiicrtevne vs 2 td teanrieeeeek + sehen pede Renee eee eek 24
Cerview Meads wiesecbesetoneteaased peebesceeee se Se4exg se ABerealee oe 8a 2 Se 13
Chiasmas Aner se ce deseeveney paved. e Ee SReR Ree ay Se nade EMERG Eaae Eel se 127
QUOT Siete eater ce ie ad lena a Nesege RSE Ee eG Ee yeas ene SRS 127

PE OIG OR sie Sicicd os eres cretindtispaeelsiss xa: po weer aeaveison aS RIENS Fs, 2d ua esa a Saaee Ea Se 101
SSBTOMACH ep sinneth 624 C0 cba Ga lie OS 8.8 doce SN at eat ch ease. 90
SODYING.” 2 i:a<- bata tremmace ee bc OShssd aR oReen cameos oe sean eee eens 101
Girculation.of the. blO0d csssccene cence Se eect cccek SNS edna AG Oe 107-111
Circulatory: @ystem<yiccicec cans Jonas sniten owiehe sy pose passe Rigdeie ss 107-111
Circumcesophageal commissures, defined......--...2..-0-- 0222022 e eee eee eee 124
in honey bee... 2-css-esxesescssaaeeccsaiaers. 126

Clasping’organs;. defined s.2<-wevsces see's ss seca eeeeeasee sess e Sechdecee eda 24
OR ARON sie ule at ce ee tes eats eee ete eAc a tiatereys 73

Cla wss0f tarsus :. 2)..2csccaciises: 28524 uaa eeeaseis 22258 nattns eels 22, 68-69
Cly peal sutures sca cocsdeuagdiiecaaet 245s cacamkewanhenie soe oe Ackaemeeesee 28
Cly pets) defined. ..:.a2qsacteneseassecncseeaned RR RERRN EG one eeS 15
OPNONEY* DOO: saad cascccae tees ce eeaeeeceo seas bie eee Roaeas 28
Cockroach, Blatta, development of head.............2-.....-------22-------- 18
CommMissuress 2:25 ue deleiiiinsdis eee sa gsge degeniee Meet oe eral eee oan’ 124
Compound yesee: 2 ce xuvvestensceesy ss ¥ 54s reeeegeddder ss ces srs eeeyieedds 27
detailed structures .: 22022 22i2cuseeniandas <e¥ ee ioe eyetces 127-130
Conocephalus;OVIpOs totes os ncderaek od ccctee oes Seaanomnnnes Pees Coan aeaes 25
Corbicula cow's sc cde cadeteeesea duties bARLIA Gateaeseeagl 21 S5 see kemeeeswes 66-68
CORTES oorejeie.S:che 3, Ses Sd coe AA eomme boa Loe Oe ate eele ae aks eames 27, 127-129
Corneal-pipmeént:cell8jcccscesceeanccomcane ettes sate oceaese ce SSeS 129
Costa of cenéralizéd Wang os c<2 nesesceccean Sees ce eee eem eae Saws: c aisle ee 22
Py Men optera so25 cxiatsecovicionitedle s opess ciate Retails 2 pleated se 59

Cora -dénined 5. cieaosicti tend woasceuet alee: gecets tate tnmeou dese ws aaa 20, 22
of honey be@sis sc2sesvacctveasasegie yes ees scsaedeeacemes er sssa ca deeeee 67
Coxo-axillary muscle of wing of honey bee ......-.....-..--------2------------ 66
CoxOstermuUmM, seis seks He eed aceteele ces ag eee dedin bovis aed eae 21
Cranium, internal structure -..2occceneccneedok ones c 2h eee seine s es ands edie 30-32
Cricket, Gryllus pennsylvanicus, mouth parts..............--2-2-2--2-2--2-+- 16-18
Crop; denned .ccincangurs ss ccc mannanaiamacaet de anie een seseas tena 90
of honey bee (honey stomach) ............2.220 2.202 e eee eee eee ee eee 94-95

Cross veins of generalized wing.........-....-.2.22. 202020 e eee eee eee eee 22-23
Crystalline cone. sesus seccecnes sca eeanesecaeessseeedde ereedddgeke os exe eee 129
lens. ocdede eves Saas ewes vera evaeeeeeieceeeh sores ves 129

TOs s2jgecsceusesed se Sake tee nodes aoe 8 Sena eee ess Bas 129

Cubitus of generalized wing......-.---.--.- 20-20-2022 e eee eee eee eee eee 22

Hymenoptera.........0- cece cece nce cece cence ene nncnaeneennes 60
INDEX. 153

Darts. (See Lancets.) Page.
Dendroctonus, “preepistermum si. ses siccecc teen ame ye Vee eee eo ceneee ne dele 20
Depressor muscles of wing of honey bee ............---2-0--00- 200-222 e eee eee 64
Determination of sex in honey bees.........-....-2--.. 2-2-2222 - ee eee ee eee 139
Deutocerebrum, defined 2... 2d edvasarswauyanaiietiisileee ss doe: Secce.s cs eee 124
Im honey bee's 2iscisisevbineiade de cs He atesasse dad ears enacts tie 125-126
Development, ‘defined ......0:scchesaeceePastaesaus vee ss et iees Sree sovlnensees 11-12
Diaphragm ‘celles... ces 5 caveveseanesetccasceslgeeve¥¥ys ceeyaeeissexkenseecee 110
Diaphragms, defined 25. 0s. ss0ecescseccceedenese eres reso. eeseteerseens 107-108
COrsAl gees oy. yee eine heated degtoss hive ee eds ise eaedy 109-110
Ven tral tise) ic a's Ses Geeelos eed nee Sede dee e ey oe ek Jakes 109
DIA QOSHON'. s.e'scsise sjaguse ae 2G oa eae Acne ee Mee EAE eee cee heels 86, 89
assimilation, and excretion, general physiology...............----.. 84-87
Dorsal diaphragm)... 2224 sh as tescnscisncesecicneRelndnes rs o28 22659 DoShes 109-110
SINUS Sse cie ects teins Soca Aa ea MAaao aia ee eRe eeegan zeta 107-108, 111
“‘Dorsocerebrum”.......-.-.-- whee ase ade Pyetabalel Mure aA SMa a1 ceca 126
Dorstit, denned). 2o.s220 402s cos earenieereceneseceaaederine pees sce amerncie 18
Drones, deAVed sence nce wets cece eer eemneremnaanacer eRe Sees sediodvios 130
Ductus ejaculatorius....... hb ine Slee eas Gea em eee SERENE oe ee ected 132
Eipg, défined sj: 2c20stc0n sc osc eseecenecneeecateneeninendlns ods ee wv eeeadaees 130
fer tth ZatlOMsisaccocte Saran dacs eci nome awe E ethene soe e theses 137, 138, 139
LOPIMGUL ON: sees cance as ancestsrsiahehcilsiabotaaly es MIRA ah ee ee ta eee een 136
Elevator muscles of wing of honey bee.............2.2..22220220 20222 eee eee 64
POMDryO’ sores sieges owelys oe yee gs decane si desneus te ee veeetdosawdell cee 12-14
Embryonic development, defined...........2.-22-220200 220 e cece eee eee eee 12
Empodium, defined 0... s.sccssiees cess ercees sci sey esgesweediousaeeeees ie 22
of honey’ bee cacceesevee eevee ee bese sneiss tAaeeeeseth tases sss 68, 69
Bintocranium..... esiexesvere sed onenaernatanwe wanes Ste Leedekeeb es sedi ces eee 31, 32
Entodorsum, defined...........-.----------- Mi dias tleeR ada ee OE Se Ce Ree 19
Entopleurum, defined... - ..22cs020seeeeeces ie scence hes seeeee sees ee ees sees 19
of mesothorax of honey bee. (See Pleural ridge.)
Entosternum (furca), defined ...........22 202-2222 cece cee eee cece ee neee 21
of prothorax of honey bee.............22-22-.02222.22-.. 55
mesothorax and metathorax of honey bee................ 56
Hntotersim, defined .ncsveon. sso tees adacecigneilemdeddaucgume reas Poonsecax 19
Hintothorax, denned so isso-cense essa daeatcinngabeebassseenaceutie Seco satcels 32
PNZYMES ies! skaiaie 32.53 Bess zencamaeaes Sala a etalaa a autaranaecete ct aiatetstatyaha 87
Epicranium, defined... -.2-.22..42 see nacantacaieangeeroescaceiucsssesedusee 16
‘Epimeral paraptera (postparaptera), defined..................2.02.22.-0.-.-. 20
of mesopleurum of honey bee............ 56
Epimerum, defined... 222. ssnesestenonnemeemeraecaeaawiebiyyees eye yess used 19
of mesopleurum of honey bee.............2.2.0222-22-00-0-00 222s 56
Epipharynx, defined . 02.0. .02642.sceenesescd voce oeeunedeanye eb eee eees eens 16
of honey bee............2.-222.... “ASRS NAM eth toca n  oe 51-53
Sense OgaNs....-....--- 2... eee eee ee 52-53
Epipleurites, dented: 2ccccccnens sca oiaiais esas oaasaeeneedents o£iy a aae dae 24
Episternal paraptera (preparaptera), defined..............2...20............. 20
of mesopleurum of honey bee............- 56
Eipistermumy, defined s..c8s.tee sacsk is euaidivavebderadiie sicegeje Gances oe tee belek 19
* of mesopleurum of honey bee..................22022222--20----- 56
EXCICUON & - ciecivield seth smacew's sees 1 eeeeUN ean np cisie MeRaaeer Soe acne anaes 84-87
Extensor muscle of mandible of honey bee.............................--.... 40
External genital organs of drone honey bee.................0..0.00-0022--2-- 72-73
154 THE ANATOMY OF THE HONEY BEE.

Page.

External mandibular glands............2.... 200002000 e cece ee eee eee eens 41

Hye; Compound: ccc ence cts nee msece cao es eee eos ideale a cot eeoases 27, 127

BLN Oasis eee Sacicicke Since tact wz earn soot WW edee te ore eisai 27, 130

Facets of compound €yes..ccscocccsbickids pes sc eaentuce beanies soca suis aacte 27

Pat DOd ys ata heats sets ta dclaeaaSe hil vohiiatn eee saul nase te oe de and 119, 120

and: COnOCV1CSvac:sesae se upaet te yy eseeeteaeeededey ss oes <d4 seaweys 119-121

Female organs of reproduction...................22--22-22-20-02+ eee eee ee 134-139

Femur; defined: <:.9 i149 jis eeede eles de needauee edad ai ewie a eceeeeuens 22

Of Honey: Wes cc aussie ARS ee 6d Ieemasemings< SE DS455 Sages 67

Fertilization of egg, defined........-..2..2.22-22 22.0222 e eee eee eee eee eee 130

ob boney, bée 2.22452 tennoeleaitesacearescseonadens 137-139

First abdominal segment (propodeum)......... Se Nee ean eterna 58-59

Fisgelum..cc cece eeteewss ou eine elas ee eer eeendetudes oe Sew esate 32-33

Flexor muscle of mandible of honey bee..........-..-..2...2-2--2--20-20---- 40

wing of honey. beessc...2 6. . etaeacekegebaeey couse yeeEasee 65

Food of adult honey bees......2s.00s see5es 4 veusecseseseuese ce ee ee evaeeenee 89
larve. (See Brood food and Royal jelly.)

Foramen magnum, defined sc... seses4sseedecveasdieey ce ovessssaneeeeds 15

of head of honey bee...............0- 20-00 e eee eee eee eee 28

POssacOl ProDOSO1S 24sec Seay eso sic aoa Reaniesee Giese be ees eee 28, 46

Brontal panplion viocc Je :ewissingscs2 22. be gutalaqumeninee sate ees gees davies -- 1%

Pront; Cehne ove ssi5 sive ae bs 2 oct eaatidlndenei ede cece se bhoedeceemees oaides 15

of head of Honey bee ....20.22242<24sseebdeseekeseeees ood ecgaebeee eds 29

Furca (entosternum), defined...........-.--- 2-2-2222 e0 eee cece eee eee 21

of prothorax of honey bee...........--2.-2--2---2+----- 59

mesothorax and metathorax of honey bee......-...-..-. 56

Galea, defined. vaniccnseAsegseue seal Saeco Rei eeies Po ae ee eeees eae 17

of maxilla of honeybees... -.. ac Andanaedes BeRGeGh oes 2 ee igs eehee 46

Ganglia, defined ..).i:c20sitapewive Jy 2 visio 4 oe pe See eo Seeek kus oe eee eeeweeeeese 124

“iGaumensegel” .eces ve x22 eens cscs cucuseveteeeekeres ¢24es tih4 seeeteeieceee 52

Gene, defined. :asisweqdegee eye ceteeied sablowoeesddane dy ese: iseaeeeesecese 15

of head softhoney- beesi.. e+ <a 2 25 cai dee noes educate aie 29

General physiology of digestion, assimilation, and excretion..............-.--- 84-87

Gil CORTE sis ois sissies ness ee oD aaa s SRR Sage ede gusdeade oe 2 eae S Ciseeehduardiecdake 112

Glands, external mandibular.....................22. 22.2022 - 2222 e eee eee eee 41

interial wiandibular-. ic ecsso.tceehadonteeeueedss 2asg sae eeeecees 42

lateral pharyngeal 2s... 2o55822c.cnnerccneccsacueyseeeeseemesctaecnes 91, 92

Median. Pharyageal : oo oc oon cS spegnamauicem ness vie oeieee dian wereetetels 91

mucous glands of male organs...............22.-022-22-2202 222 e eee eee 132

OF Nassan Off assis. dcieeteie'e ice os Fick eda e ce ess poops 2s ogee eee 83

SUING 5.5.5 sisciete eke oe ee ae echidna 2 wel lehe pee reees 78-80

BCs set Seis is Sol aceite Stetson yyves4 pia aRone Seb seeks 78-79

alkaline . 2: vececseeexex 4 smueeevaciecex.ds sees vs vay eaeeescs . 79

“lubricating” 2. sviwinunosensddeey ye eecde ry sgeiees aden 78

Posteerebrall ss tse scetee ve ees d cbt taeda atideue ces YECsa ees ettduenes 87-88

TOCA fysc Soe cla seienr ee ne bond eeOnaeeenaneoawors clic ckanaseaeules 90, 106

BalUVALY,\ Ol WGad 3 2c. cuisand sparstamdens ecisedaciet Sida oe oc. oe Sana ele ee 87-88

thOTER. ci dtacdeids wid o bQs Rid desea etbentearccane 88-89

SUbMNGUAl . no.cceceriee2stcs sc chachstcelnnagetis ea cenaemeee sees 91

supracerebral...........22.-2---- Sunes AS eie haa ora ma eeeeeecen .. Od

Glossa, ‘defined o:ccxccau seancas Voces oe ceeeiiemereeeesa see e see SAseemenete aki 45

details, in worker of honey bee........-.--------------+----2- eee eee eee 48

Glossee, defined........... Fofefcfuls occ slals ana etovagdaan enon cmap aay coo aaa etiels 17

of labium of generalized insect......... gis esa|Rate stv ess sci ere RUISEE 17, 44
INDEX. 155

Page.

Glossall 76d es snivess vase ianlormniaansedcesracctessetetiias.cee33.03 tethers 48
Gonapophyses, defined...........-. 22-2. 2-22-22 eee eee eee ee cee eee 24
of ovipositor of longhorned grasshopper......----------------- 25

sting of honey bee.....-...-.------- +2222 ee ee eee eee eee 76

Grasshopper, longhorned (Conocephalus), ovipositor.....-...---+-----++---++-+ 25
Growth, defined... .. 00.200 sso20sctecndeaseeneseeee saree ce eee eeememeene ns 11
Gryllus pennsylvanicus, mouth parts..........----2-+--+2+022 eee ee eee eee 16-18
Gular sclerites, defined......-......---- 2-2-0002. eee eee eee eee eet eee eee 16
Heid, déht@diaic.n.nnanstanccasiescsedaiaucde seuss eee peed ereltadntas 15
of honey bee and its appendages............------++-+-2-2+e-222 220 2-- 26-53
external structures... ccccccsecceds oes sezec2eegerateesee 26-30

internal StrUCtUIe ccs. ccceceeece see sees tee ge eaeeess 30-32

worker, queen and drone, compared ......--.----------- 29-30

Heart, chambers: <is:o402ssenqniecneedncaneweds sector ereecs eee eeeaEeteees 108
” general description..--...-- 22.2222. .-2 eee eee ee ence eee teeters 108

Of Honey beesav: cas hecaduteentcuseacccereeter tis tasetaieseemeem ees 109
Honey’ stomach... c..0sccosseeaecaonesear ingen serene ected See esas 90, 94-95
Horntail, Sirex flavicornis, first abdominal cepment Lear eebhdh mm akeppnemee 58
MetapleuruMicccswsev ewes ses ad anew e scuba 57

WING Veils: s.cccteouced cee etatmedemeenasakeascieeh 60-62

Humeral cross-vein, defined .........22.--2. 225-500 eeeee ee eee eee eee eee 22
Hydrocarbons. sacngaacieneiseentienteckauna tne eae eevee sen d4 se beeen 89
Hypopharynx, confusion with glossa of honey bee.....-..--.---------+---+----- 44
Gefitied 2.) ssttce lnc mtsnas RSs See eee ER OOSEe Ss Mea ents 16,17

Hypopleurites, defined... 2.02.2... 2022220 20-0 sescc ese cenmnnieernsneeteeeee 24
Hypopygium, defined... .2.s.02 0.02 2 eee ced cece cess esisneaneenne nese ne cee 73
Imago; defined. vic. 2. e228 22 css Boaciwe cued faded aeeeeaneeaccutestecee 12
Tngluvies, defined ecw. eyes tet. ce sca tassaua sear ee opiate ete meetees 90
Insects, general external structure............-.---------2+ eee eee eee eee eee 10-26
Internal mandibular glands... .... 020200600005 oc cseese cece eeemeeeeeeeeesere 42
Intersegmental membrane, defined................--.---++--+- 220-222 - eee 14
in abdomen of honey bee..............----------- 70-71

Intestin@ y+: svgsuevesbieg seeds ca 4s satsisericeanocaianeeetecmeeaes 90, 105, 106
Ttycorsia discolor, WIDE VEINS su 20... ico5 ssa narciocecimenaenose Meade reeaeke sey ee 59-61
Joyful humessssicecy da asanscdetadeassochos wade cieaeeamaredase ye ee ess 83
Katabolismyjs: 1/4 ¢sucde gens nos tidnadaddsigideng ease meweGeeeeeanaae vera se os 86
Tabellaie sve 2c seas lor ewatsl dad aas cetaglaalae dine eee RSS CE AAMUEREE ES ees oe 45
Labial: palpi, defitted cise c p2sisaisiaisiitien cid cistard tiatsicln eb eee tenes ele es a2 ee 17
of honey’ beeccsvntensandesoddgeduncekaeehscneauseerere ye estees 44

Labium, defined cccecceeyesessceoreee dose dasesseeeeegesedadee yes yeveeecses 16
of generalized: inseCtz. .acivscveseunscndaeasesaseer sees ix sees esse 17

honey bees: saccaseesessimnswnees denaadeecene dee sk ter es eee 293 27, 44

Labrum, defined <2 24 022 2sqseavenseceorsyeaceeesscceeedesecee:seseeseee ess 15
of generalized ‘insect =..04:.¢.0. v2eesseetexenaneadrenre i cess cesses ses 16

head oF honey beesse.vtassiebet ess oceekaber sevee ey oe see's oe ees 28

Laeinis, denned .is-savanaipitede os etuaunadue oeermaenree asce ne seaers 3s 17
Laneéts Of sting 5:0 ue anicoesoceeeanmate oan ERE eeee ald EEE 2 liao edocs eee 75
uA GOIMLOSUIME): aie ze evens Coated date Bema uaneesbegis sits haloseeda cing 90, 106
Manvel, COHN: 26: 6 dean yetonr ei nonhaceaseeteuansaeee Les tateus ta aa eaehe 12
Darval-stage, denned 5 ses oi ach.adadbacceds aocknbhiveaee 6055295 2265 oeaentens 12
Lateral pharyngeal plandsiis scsi cea udigabanidwan te: es oe dcee 02S ynavieaiye 91-92
Datus denned. 22 as :os cece be cae aRgsee ed Aer hotee ecco nee aeeaees 18
Legs of generalized insect........-.------.-- 2-0-0222 cece eee eee eee eee eee 21-22

worker, queen, and drone...........0. 0-02 e cece eee ee eee eee eens 66-69
156 THE ANATOMY OF THE HONEY BEE.

Page

Ligula;, defined 2 ssssccsccnenso voces ysis a aewliidas ae Coleeect eee ss 17
of honey bees s.cccciisc'sist tolsiea phat oibe macau y aye myeeamae er euaie 44-45
Lingua, confusion with other terms........ chee nadie set's tatiendtle saute 44, 45
GeHNE dys yeawessmiedeee sso de eve isis stukeured seh <haeaaeeameneeee 17

AIG OF UIT i sehen attest I ht ciate eae tues anh eel ty a eee Cpa re Gta thee 46
“‘ Lubricating ’’ glands of sting.............2.2- 2222222 e ee eee eee eee 78
Male organs of reproduction. ...............2..2.22-02 0-2 e eee eee eee eee 132-134
Malpighian tubules, defined ............2.2..0- 200.2020 e cece e eee eee eee 90
Of HONEY Des: nk aonnsess teu edsecc acc canasee *...- 105-106

Mandibles, defined.....-...2.... 22.2220. 2 eee eee ee eee eee 16
of generalized insect. ............---2--0220 2-2 eee eee eee eee eee 16

honey bee.....-..---- pete biswuiushb aah aka de Umae 27, 39-41

Mandibular glands; externas sv xq <2\s2eeveseheandssdeg ss ese ceeseueseesce 41
Toteral pissy sess sen tleesecatdeee vey Vetseneae lt 42

Maxilles ehned :20 aici ews he elite a Stadt eee ess dre sep ueaa austere 16
of generalized insect. ............-2.--.---------- Faeeeee ees 17

HONEY beGias ic..52- 0s. naw dn ndeadeseee us Lanois ee eesobee ages 27, 44

Maxillary palpus, defined. ........-...-... 20-2220 e ee eee eeeeeece ee eee 17
of Honey: bees. to nnaccecmeacccseeetsieoscaaneesecen cee 45

Maxillary suspensOrn sos. cose 2s os setsien ee Pee ees A Oe eee eee 32
Median:pharyngeal glands)... 42). s6<es.ptddgeeresiuiek cnc ceue ase vassal 91
plates of generalized wing... -.......-.-.--.2--- 2.22 e eee eee eee 23
segment (propodeum) of Hymenoptera.....-...------------+----++++-- 59

Media of generalized wing. ...-.-..-.--2-2.-22 220-22 eee eee ee eee 22
wings of Hymenoptera. ss223).s2costwerdexGrey sees ssceseeonte ees 60
Medio-cubital cross-vein, defined........-..-..--22-2-2-2---2-2--22---22---- 23
Men tuimi, denned os) oo ie acaleley aise oialejetdpe rece tim cper erm eieercimnne eed gtd oo ante ewrere remote 17
oflabiumof honey bees... acs .cciescicacdscgiens ses oc eee ve gdeciciaaeas 44
Meésocephialie pillars. 2. 0c.200 oo: et ynreenslsielicede seer cees eoeanorsslek ace 31
Mesopletinitt. oc. sccssac ys eee oe SesieasceestanGaet ree c ses Meneeeseeess 56
Mésostérnum.. 2c os csanase ese ke ce seimrmeseinck oeue Se eos we deseeweneetelaet!s 56
Meester ours testa jetcteiaitide sev.c ere ere oisiatenle SOUL sais qe cradle ae ese ete 55
Mesothorax: defined: ..0-) Jy seiccd suisse gap eiskenieniee na nee caanneeeeeecane 13
oft honey bees s+ ss wea: vtexcnsstecceene ses tet ee esaeesesedayes 55-56

Metabolism, defined «:<0:c0-c04 scacceeseee dee deed ee ees Sse exe sieeeceed = 86
PIOCCSS ieee ihe ee Sa ecine i aeon dace ayes seeete mm uiaceimiees 115

Metameres; defined ..-3s. 2. ese ovendumsesancedecees 2 ie 22 ocemdienedenases 12
Metapleurum...........-.-------2-+------- Bia ahahte cgay ose 2 Sass iar taderiaeatuees es 57
Me tastermuMms ic. auvdiea weenie i scce. cae netan Shucedldget leone cet emaewnsiegiesd 56
Metaterguiiis. .:..nectitcccu a 6.agg aonens nee guceiied toceksPaubnemataueetame 8 56
Metathorax, denned s..ca00 sc. ccranameencesecctasiar sts cadeeeesesceeseeseee 13
oPhoney be@i sco ss, nsamccage ee vee See Scie ceeenaas Meee 56-58
Micropyle:ofege, defined 2.0.2 0's scacceiisscincacna: secre ss eraltawrenreeeseizils < 139
Microthorax;, defined nc 2s. ss sensenduticee eases oe dacgecenecee tenes dedefels xis 13
of generalized insect....... seeg See orkere sos $sietasdeaeseawenye : 18

Motion of wings in flights o..<2ss..sceoccieeecewees veges dh eceeexeeideweex ee 63
Motith,, deéfitied... 0 3c.0c:nuee soe sc oeaoaueiedesene esis i seeaseeectare ss 49
OPHOTEY DEC ie ead newisi oor een veaeekeintecteee ys sees obs Ae cee s 28

parts, defined oases lec ecschchincanececa en: obsess oS eeeeectae aes 16

of peneralized NseCti... odccisenicecese ce Lie sacnnicndnsecieee a 16-18

NOnGY Ne6x se ne tomar eostecacewetesns. fe ehsostedease 27-28, 39-53

action in feeding..............-.-.---- er 46-49

Mucous glands of male organs..........-...---- bb Di hd aie a aelavbects Se leeeegyare te 132

Muscles of flight. 2... 2... ee eee eee eee eee ene e eee ee 63-66
INDEX. 157

Page.

Neck-or-cervicum; ‘defined. :3. occsseeee eve. c deceeuesesenesaseee lines ses 13.
of generalized inséeCt oxy seccsscasarcepeszasieass Sesseexe 18

Nervous system and the eyes ...........-..2.22-22-2220 022222 e eee eee eee 122-130
general description. .........-.--.22-2--2202-0-2-2020-0-+ 124-125

PHYGIOOR ye ee os tysee bE eee eee ee 122-124

of abdomen of honey bee. .............------+----+---+---- 126-127

head ofhoney bee. ac anos es eased Pe Ne weenie 125-126

thorax of honey bee. ...........-.------22------2----- 126-127

Notum, defined..........--.-2---+2 22-2222 222 eee eee een eee eee 19
Nymph denned «tie ciec.cecccrceneas gare eee ele ode beac a ae acenaee ee ek Rigs 12
Oblong: plate Of sting ic 2.22.cicecdkeleas ees sete ba2d02 24604 Cas Wheel Rbeehe 75-76
Oteiput;dennedss. 2 ion gie sees hs Soe ec 222 cade ide aR Beale ses 15.
othead of heney bGes <2 decease ssetei4i 22 eescueek teehee 29

OCENT s 55 = eiiacinpcidttence a misleg iene oenimeida Dede SsGaoes fied kecadsed SAL Gneens 27, 130
Cnocytes. . ieeieisedciieaeeeeeteennad agonal reeeeeken cee UES, 120101
Csophagus, ‘defined. siberotiagngal nda ua ean anes Atta bass ene eo aay eac ne 90
OL HONEY DeCreut ccwcivanencaeses eanteossetwaueen dae eoe 94
Ommatidia-of compound 696.6: ccsnscrniensweaennaarn.y yee edema eee aeeoes 128
Optic lobes Of braiN.....22c.cceenrecacenseeeaeeeaee eee i eee cege ce petals 124
Ostia Of Hearts: 2 o:.cscaseoecia te codescwssces meee t SEH EVE ie beens: 24 cileleitne 108
Ovaries, defined «2... c0cccccccnesececceucneceseseeeteseedeeecac sce sesceedee 134
SUWUCLUTE AN QueeN: DCC sioccsesceueneewncsee nesses ceases seen yeeeeers 136
Ovarioles;, defined sci cccaicicgut anette ie sea eereiae ia eiaeinve Val ee Seg Fee sean 134
structure in queen: he@s..cc cme nceuwermanevedin,e 3s te Fede saeeees 136

Oviducts, defined............- belated acne eevee espe eee se ew yeas 134
OMpOstOPe 25.04-sistet thant ck tors eds Bau anne rece aul a ee Sa nee cic ee ay DE OG
Palpifer; defitted:< scdcaocos22ceeseeedeseauiccsAnessey ees douse f2dd54545 eens 18
of maxilla of honey beCisws uy vgeite ite ny eevee yyooehaliasenas aceed 45
Palpiger, defined os 2200: seen send oiseadelvakeed ig i tees ees. oyede nt. .c. see Aeabe 17
of labium of honey: bees sccsucexs spscneg.cie Gaesedee csteecbetsseuaans 44

Palpi, labial, defined! .cxsscarncescudueiwe@rgagevayees eveeeebs osacn0toaneece 17
Oi honey bees: vestesececn seals {ocecdadeuy s25h174 ben nese Reons 44

maxillary; denned ss occ kaa sece a shahehesoige sree snaeanahaca canine 17

of honey bees ices ee Manel cnneoac keen See ee 45

ol. stang’ol honey bee. -.ssncced said eaeee keel aa cod oheeexeees geese cals 76

Parag loses :<d ene dre coacus Gina tae AEG eas eaten danas anes 1
of labiumof honey bees os ccc scien eueicawanee nee aeeces see aeiciee 44, 47:

Paraptera, defined ic: c.cenctdini daa ae Sa eieaeaa areatelee Shawauecs ands 20
of mesopleurum of honey bee..........-......2.--22- 22-2222 e eee 56
Parthenogen esis. ...c..2saotvaqennandastencseentannncce teyeheGGss «sree geysers 131
BMS. <. 2c nehananssuhaeakenasnoraaneaoeematigecseeam eyes gee sea pegs ae eR 132
PePs1s, WINE VES 292 =n accctieneccnen esos ae Sune ie eleles ete gy yee oneed eee 60-62
Pericardial ir 8AC8 a..cnscceeyesconecce vie sdnaeuhseliiiewe's veteneedceeieesias 111
Gels. .ccaccses came uer same eeCaese eee sider a ea eee e eet 111

Cham betnd 6fined 2232 se Soto eee eid ceded nse eee ed eee awe as 108

of honey bee (dorsal sinus). ..........-.2.2.2-2.220-. 107, 111

Peritrophic membranes........--....02. 20000 e ee eee eee erence eee e eee 101-102, 104
Pharyngeal glands, lateral.............-.-.2-2.22-+-- EEG sens eae aes 91-92
Medi aN. 2e's sao se-deoeedeawasseweusees Pied ligticanwen 91

PlabOs caste aacite onion ge JieesiaeareeEneemnaes learnt bee keaed se 50, 91

Pharynx, defined isc a.i02 nin tieni ones steeceegtaneeseuess 2h: sk oot okeedae 90
Of Honey Dees svascadeniue showsecieeeeeetenassanved $525) 4peuenesd 90-91
Phrapiias Gennes cp ecvicrcaveeinctibe ries senen etme eek ww uatess on22 8.0 ean ses 19

of mesotergum of honey bee................222 0020 e eee eee eee 55-56.
158 THE ANATOMY OF THE HONEY BEE,

Page.

Pigment cells of compound eye. ..-....-.-. 22-2202 2 22 2c eee eee eee eee eee 129
Pleural coxal process, defined .........-...2.- 2-00.02 e eee eee eee cece eee ee eee 19
ridge (entopleurum), defined............2.-2-..0202220-202e2 cece eee 19

of mesopleurum of honey bee.........--..- taeda 56

suture, denned. 235 h.gsk vameste hes 72 cease a cae inlay eae 19

of mesopleurum of honey bee..............2.2--22-22-2-2-22--- 56

wing process, défined sa. .e0sss6 Goons sseemdtaceater eee ceenasaas 19

of mesopleurum of honey bee.............---2--2------ 56

Pleurites, deine? aiid: eee ne eesev eas ca ied eee deamon eye L30a4 doe eeaee 14
Pleurum, defined e4.ecccxaws ae wedews ves Fanaa eee bs so esc x eee 14
of generalized imsectscse.gca057 ess taesdaeaee dase yt tetsageeeaeewe 19-20
mesothorax of honey bee..............---- 22-22-20. e ee eee eee eee 56

metathorax of honey bee.....------------ 2-2-0202 eeee cece cece eens 57

prothorax of honey bee........--. 22.22.22 eee eee ee eee ee eee 55

Poison glands of sting of honey bee...........-.-.--2.- 2222-0222 e eee eee eee 78-79
sac of sting of honey bee...-...-5.-..-...--. 202-2 e eee eee eee eee 78-79

Pollen baskets of worker bee.........-...-..-2 22-2202 e eee eee eee eee 66
Postcerebral glands -....02400:esi0-¢2+00 02s seexcnccesesaaeu stevie eae es pececees 87-88
Postelypous, defined . c.2.00c20c 28 caidae peeoceewe St et Bee evar oi 15
Postembryonic development, defined.................2..22---2-2-22-2 22-20 ee 12
Posterior notal wing process, defined............-......2.2--0-2-----000220 eee 19
of mesothorax of honey bee..........--...-.---- 62

metathorax of honey bee..............-..-..- 56

Posteena: defined jc cece esse ee cidecten eee we eee en see oes ere eeseeee 16
of head of honey! bée:.o..20. eae cccameeedendenc tees 2s sade sansase 29
Postnotum (pseudonotum), defined...........-.-.-.---2- 22-22-2202 2 eee eee 19
of mesotergum of honey bee.........-..-..---.---- 55-56

Postparaprera, WehNed suacish cnn cae dasa ediieattieriecendenid bf o2bsGe2k peeeN ORES 20
of mesopleurum of honey bee.........-..-.-.--2--.-2.-02---- 56
Postscutellum  déined o..52cosy00..c.c02smnomnpennceacans ta ees saates eRe 19
of mesotergum of honey bee...............2..22-22-22220-2-- 55
Poatsternellum: defined 2.20. .< 3.2% dsc deed beled yp des doves ad sda dsaeeeS 21
Preepisternum, defined 24.2324. <2449 ¢ satis stu ees oe eee geese spyederie’es .. 19-20
Preoral Cavity: xiosjesccec feet 8 oe eee cated pe ee a 8S eee pat tnanlis 49
Breparaptera; defined... 222% 02 ey eee ee cea toey se hee Ge eames 20
of mesopleurum of honey bee..............----.-2---22-2------- 56

o Preseitam, défined .iasesues 2 2s2ae os teddies aieaiedl ov: io8e a6 AeoeenAcs 19
Presteritim, CéAmed...2.2.22.2/0 secre cd sn adsevinsmmonin bory Ses eaten hubidyswatan 20
Prob0sC 18s socesesenctediny:+oi24 028 Abeihebacemcewe Pilar ies 2eteaaearaams 27, 43-51
Pronator apparatus of wing..-.-..-..------. +2222 cece eee eee 65
Propodeum.....-.-.--- +--+. 2-2-2 e eee eee eee ee 58-59
Proteidssniveyeacteag eiociac: Spe ae 8s sGernteecueden Pus fetihed a enimenWaigaul'y 89
Prothorax, defined): c.2%+2.2.422 4 aenesclica unc prpeuty tel: gee een ater ¢ 13
of honey bee...........-------- SeSieeeeseeeeete sveeeaseeeeas Se 55
Protocérebrum, defined : 20: 2220: weecunte seeds et ees os eee yes ecdeenes 124
in honey, Dee osc chain ae hear Week ae Mesemsa sek eiaes 125
Protoplasm.......-.---.----+----- ses Ge easiness Cmseatin mS oie ie te Sabieme aba raieineece ae 86
fC PROLTACLOR MING UCR” aiieietes 2 oF ec dvsciaiam pussies P42 seca tagecsaeeealee hoe 51
Proventricular Valves. tans. cc enc teteadedeeena Pode ed cn 8 pheheinecaaceniecss 97
Proventriculiis, defined vac ca: 2scnictemenmenis + EeOHe eae A EPR Reecee SEARS 90
of honey be ....s.00000cce0 see eee se peek ereceea es oe ee 95-98

Pseudonotum, defined. 0... .: ddscacidecusuagses cee eee ogame oar: se 19

Psithyrus, pharyngeal glands..........-..-. 2-202 e eee eee cee eee eet eee 92
INDEX. 159

Page

Puilvilli) defined wc ccwnccperedeumsis aves Pees Poses 4824 ae se aeintelddinete 22
Pupa, defined......... et Na ah Ne fettctat ees RT ai tate a et latea ber i 12
Pupal stage, defined..........-.------ + 22-22-2522 eee eee teeter eee 12
Quadrate plate of sting of honey bee..-..-..-------+-+2--2- 20-52 e eer e eres 76
Queens, defined............-....-2 2-22 e eee ee eee eee eee eects ---- 130
function in Riven: xcccckeeemecmsecks Hee bons cea rede eed 130-13]
Radio-medial cross-vein, defined.........--..--2--. 2-2-2000 eee eee eee eee eee 23
Radius of generalized wing. ........--.-- 22-22-02 2022 eet e eee etree eee 22
wings of Hymenoptera..........-.......--2- 0-0-2 e eee eee eee 59-62

Rectal glands, defined.............. 22-02-02 2 see ce eee tee reece e ee ee eee ee 90
Of honey be@ccsesesei es es sv egecssegieewe ders vos arena 106

Rect, defined): 2.2022. cceeekse yee ees ceeeeeeesiceaiag esa seeeeenesetnieees 90
of honey bee.j2cscdee2es eee sees se esysseareeececieeeys He eeAes ---- 106
Reproductive system........---+.--+ +222 222222 eee ee eee eee eee eee 130-139
OLGLONe DOCS e230. see eek aL Oey eee ey bee sexe seeee ee 132-134

queen be@2cceiset.augese hee ses eeegsesesaueteeee 134-139

Respiration, movements ..........-.---- 22-0202 ee eee ee eee eee eee eee eee 118
MUSCleS: AS AUR GRigeeasemn sean es Pet Meu ameter 118-119

pliysidlogy. ssc esc ehke ee Sesh asses osi edd oe see 112-114

Respiratory Syste -.)..0cccaceenoeeeua ses st estan ne ba ee meeGne ae aeeds meee 112-119
Retinitis Cellssccccaceewacsaceeeeetir sled ci hSked aden sesee ede 129
‘Retractor lingus biceps” s.ccecescass occas 2eses 24 41 2a Seen amseanioes 51
OOM BS easement S ALR EE ESS Loe 9 SS ve ESM ale Slelamenions 51

Rhabdomes of compound eye.....-..--.----- 22-22 e eee eee eee eee 129
““Riechschlemdrissé 2 s-scncesue tends eecas cad o5 ee tee eRe eeeandadd anaes 41
Royal jelly. 2.2 2.2.2.5 2288 se sees fee ee ented see ese see ease eee toeeecece 92-94
Salivary glands......0:.-.+-.:ss0e0sseessecescs sees sens cece sea eee sees 87-89
Of héadie acs se es eee Sees ie ae ee ee ease 87-88

HhOVARS oso ole esses datenees Sod ete toe enaeeetecehes 88-89

opening on labium..............22.20-0.2020-2 20022 e eee eee eee 49

PUMP cee tec ccc l ete cee eestegstee sesasne pe Pr geuemnereesceteec ts 50

Sawfly, Itycorsia discolor, wing veins.....-...-...-.-2.--22--22-220-2e0- ee eee 59-61
DCAPCes Sane aes ae Rae eo aS ee na Sees ee ee Seer ce tawte canes 32
OS CHUM WOM ys cick caceersisie oe ecw as sem ea cute 2 4 2 gaigildsildaiae Dee Sed etsy 50
Oclevités, Meine oases he eres aernaiy oe sisiae disso pana RA De SEALs nee eens 4
DGtitellini; dened. dcszasesseamemn ee cacc ce eae nee ose see teksty ehiawigisteleaty 19
of mesotergum of honey bee........-...-.-2---2-2-2-2-2222 220 ee 55

Scutums defined 2 .,: .254nsnesascescadecs oi rg 18 | MARAE Saleen’ oe 19
of mesotergum of honey bee...-......-...2.-222- 20222002 eee eee eee 55

Second maxille, defined........-........---.---- ct tah Race sheets we Ghee a 17
Sheath of stn Gr ecac.cirSeegicg eeie cy oaks lev emedeageanscene teeMacenere ns sees i)
basaharms sss cricaeieg seve s ve mmmedncsociigeeierskemseade 2s ses ¥ 75

Dullbiss seseyietse ee cage asd ees esas clsmgweles eoSee Sea 75

SES als al ota tioned civon taker ats chants en ag Menage la tae ek poa tere 75

Simple Cyes's ies ¢ss2¥3. 0) viwheemesccvatiecnchibee WweaduaeenameNy eee ene < 27,130
Simuses\ defined siipcise:se dade eld taielaeevatio e enmewae nc aan wat toe es 2a e 107
Sirex flavicornis, first abdominal segment............-..-2-2-2.222222222--0-5 58
melapleuruin 2:2 gander excndeeesonetaee eel wcaues sa etha 57

WING Veins <2 sav xccexenewedebedee steele maaacind ocden6e< 60-62

Small intestine, defined............-.2- 0-000 eee cee eee eee eee eee eee 90
of honey: be@ vacs¢ iz engeuucinsoeesheueh ceugiymssnalearec< bes 105

Smell, Senses ox exes veeaeaasidaedetessrigaidewe neice ates dd daceaeads ses eesese . 33-39
160 THE ANATOMY OF THE HONEY BEE.

Page.

Somites, defined............... so poids Reayeyencaseranenan side ate a ham ee cine stl ats 12
Spermatheca, defined ......... 22-22... .2 0c e cece eee cece cece ec eeeececees 134-135
BURUCTUTEUID GUCCI: cacccccseece ws nasegeeeeaee sus sameneeees 136-137

Spermatozoa, defined...........22202 2-220: c cece cence cece eecacceceeseceecess 130
OLNONEY PECs Gack scnisacwaisen silicate weave aes ele tty 134, 137-138

Sperm pump of spermatheca.........2.-.-.-2.2-0- 222220 e cece eee eee eee ee 136-138
Spiraclés! defined s.1wisaceiysewe’ esa es Hewmsweteed eae ye etlattca ee, yok cee 26, 112
Of honey be@svspesesivswewdy sy $4 s4aceteeie eee eos since nace ee 115-116

Sternal laterale, defined.......... 22.22.2222 20 c cece ccc e eee ne eee eee ee 21
Sternellum, defined a... coxsediseks 22 2 Soaks Wau daedeeeips add eeeeenseese 21
Sternites, defined.......-..-..--- PODS Lei achid Nea hee rent a at naar ee 14
Stern, (6Anied 30.2 2.250 cnet ceacceraeeeu tua steenehoncemey Sones s Govdeeeeels 14
or ceneralized insect: <.cccoses Soe i ie dente seecaeena esata steamed 19
mesothorax of honey bee..-...-....--2.---2-- 2200 e eee eee eee eee 56

metathorax of honey bee..........-..---.2---2 eee eee e eee eee eee 56

proper; defined siussp es eece see ocl ss ceeaseeenee cae ee cedes aeannues 20

Stimuli, afferent, defined................2.....2.0-202000020-0- 220 e eee ee eee 124
etherent denned 2:2 venison tecigic oc Fo odes bee ROSS EE a Selene 124

Stine Mires re dnote waht ante tc Tanna ans tpt eens beset 74-83
INjCCtON Ol POIROlivasa. nce s<sreaeeeecasda ia neneaee need Gece denieceeee 80-82
MORPHOLOGY. ces cones ct ceed Foe eagemnencan ee ieee eens 77-78

OL GQUCOM: DOC siccca.3 cur ance cenaee hg eeu scepiemocanece tt eee aan. 82-83
DULpPes) ae fied aa eoe Soe eae erences ate alee, ooo oo a alate RMAedeledch ood ad 17
of maxilla of honey bee... sc sc02s08 sae ce ese oeeesiaseesey sce eesee ee = 45
Stomach mouth (proventriculus).........-.--------02-2eee scence eect eee 95-96
(ventriculus), defined. s. sasesuxsgesvs ees cagmmacedsaeeees4 34 seve 90

ol honey bee stecesn aces vanes s xeetaseee eyes es leroy 98

Stomatogastric nervous system, defined..............-2..22-222-.-2--22222+20-+- 125
of honey bee......--.-.-.--------2-222--20- 126

Subcosta of generalized wing...........2.22.2 20222-2222 e eee eee eee 22
wings:of Hymenoptera: 2 oc- sadness a5 ntalidgesilies: -odaca und 59

Subpaled ss ac25. sev pod Anas Uneaiedeaakshiaie: 22iaee va pecine dee eiecese gen 45
Sublinpial lands: sz.05655.c occa nowsedeneanGas co 2cads ao newesaaemesaseagens 91
Submentum, defined 2.25 ..c.s.ncsese-cosd. ccs anoeas aeceeeseus sees seeees 17
of labium of honey bee.............----- 2-2-2222 e ee eee eee eee 44
Subcesophageal ganglion, defined......_........-..2. 2222-222 e ee eee eee ee eee 124
OPNOHEY Db 25.c.c00euasees Sead eeiaiees oe eeeens 126

Superlingue: Ofembry ons: sass eects we 2G 2 eo c weisllehelaeine ob se cee) 17
Supracerebral-glands: ~ . o2.0<.. ccsiscemesiascuiiee cen eg s Seishin das calle 91
Sutures; defined 25.5.0 csseetecjnnaseaseeeneeies es: y ness petites ee cule 14
Sympathetic nervous system, defined...............2..00-200200202200 222 eee 125
othoney beers: os 222 2ssascmeeeseeating veoee eee 126

Tarsus, defined.......-- hue smoopieet ona eaue te ene: Ee yeaaas ese mes ese csaes 22
OL honey DCC aes ian: cesse Shouse aust esse eas Seas ees ees hee AG 67

ANSE JOU so reciec aa wate ausledereiest aS < aye Bae SSLINSA LSS 66

MASE OMG ss ecew geen oes oe Ste Leh AAs asa. 68-69

PASte O1GANS <Jcccinnc ns 285-2045 Rode wadeeeeee ns Bk oa 24 Sk eae SERS 52
Tega; denned |...034 vance. ieee ep amenenmniad SRE ee yeas me eRe eee Nee 23
Temperature of honey bets ....2...2scancssccccsse se vie ds ee sdwarsteueousenee ees 115
Tenth:segment: of Abdomen 2... aazeneveceeseeg devs ss ae e ees 78
© Menton unis .cqpandea sosise es eae ee shite ee one e ets HHAseeeeei wee eed 31

Pergites, defined wai cise 2022252 x dein setuetnes o: oe ose anal eeaeyes es oe ee 14
INDEX. 161

  

Page.

Pere tind Cf Neds oy xox es oes Bes in BAR AACA bee e eee eee ee eee 14
in generalized thoracic segment............--.2+-++ee0eeeee setts 19

of abdominal segments of honey bee....-.------------+++++++ 69-70, 72-73

first abdominal segment of honey hee........-----+--+----2 2000 7+ 58-59
mesothorax of honey bee.........------2---0e0e reece etree 55

metathorax of honey bee........---------++-+e:e2t errr terre 56-57

prothorax of honey bee.......-.-..222220000eececeeteeereeeeee eee 55

PDGRLESY foes ese se esha Aco oe Sex eae age ALPERT INR AS 132
Thoracic salivary glands...............22---22++-ee eee eee peiuities ceaee es 88-89
segment, typical...........-..2220 2-2 e eee eet eet eee 18-19

Thorax, defined................222-2002-0-2-- a Tig Hos Rata agit fed areas 13
generalized segment..........2-----------2-2+2-+e eee fossa sh itis ge fetcate 18-19

of honey bee and its appendages. .....-...-----+---+---- +++ +e ee eeeee 53-69

special characters, in honey bee.......----.-----+-+++e+ eee eee eee 54-55

Tibia, Cefined sic sse cise aiiaipiaie Seiscsleinin oe oes eee nese gs tauaamee reels a's 22
Of honey bee's 5. jseidd Lseeek hh knkewostes ese Sook 244 4ac Rea 67
OUGUG: Sess yieieetoccsantwitisisisintsl qddan nase ee Saws se oek eee Sesame ees 27, 44-45
Trachers , -Genmedis. cece oasis ts Uishioleteicisiaterd 559 Roa a SERGE ER OS 26, 112
Of WOME Y DOE oe. ciekisies2. se Salsisiecherspareatid cane eeuneela’eo idan emai s gee UeS 116-118
Triangular plate of sting of honey bee..........-...-22--22-- 200222 e ee eee eee 76
WritoCCre Drums cr... 2.22.2 aeoot tanga haad Medea sea? Ase MeRae Re RRReneiied 2 124
Trochanter, defined................ a a ee Ee gh nay Nk Sa a lie ata 22
OL HONCY, DEEs coy naacceecccaecaae es See eeu sSakeeneeweceanees 67

Trochanitin, Céfned 22 ccasicueccccaeeoocmacaigh ss oe oeee ere oa iddenhawickduautes Se 20
ORNONCY” P62 cats <ietampieeadines se seaten s «4 oa Spagees Mmmiaiies ue 57-58

Mandiblés, defitied .:\-ccs-ciecicmgrewwsaieadiveewe eevee ve sce es!s 16

rophi Gene. sa jez ccc ce oras Queue leawab eens me hee em cous age eees gala 16
Magina, detined!..cusses 2) somone ae ve weed Ay aul oe aye cee es ew 134
Wal VCs scsasuckeeeeaavertiverrcieen tes ee tee eyes ve vente Sens eens 138
“Nalvaextern a,” occ: sere vaeeenesdedsdeenasenen cucexsce sos S2eeEeees oY See es 73
OO in ert amet tad pine asin innate ie Re ried tece nes eee nik OF ba eee a Sea EHS 73
Wasa deferentiaseccowscco eceseredeceacasssveoe sey seyeeeeke ioe ne soe e eee eee 132
Veins of generalized wing........ eRSesB asian oad vise GaSe Rae LESS RE 22-24
wings of Hymenoptera...........--.2----2--- 22002022 cece eee eee eee 59-62

Venter, denned s.2 iaesnce « caniaue is qbigee costa ant eeeeeateoeeaeesiaaeensieea ds 18
Ventral diaphragm:::..:c:c2c.ahe ce Siac denen ee Gbsetsckeaageensusasadmeteden ne 109
or median pharyngeal glands.............2..222. 2020020222022 ee ee eee 91

BIDUSaseeta 2 RAN eee Aer aaah Aiea hdd Yi MANDA RNS 107-109
Mentiiculiis; dettied. casceeteerscese ec atea eee tce bees tes ce aeaeeceee weed 90
of honey bee..........2...-22----222-0 2200 e eee eee eee eee eee 98

CONCH IS sien a itea ities eeae cous ba eee ee eS 98

HiStOlOS Yeas ceases nesamennncunnanonnanecoee 102-104

MViGNntrOCCRODIULO’ cadectanttnseiotee tie bance oe ce eee eee ARREARS 126
Vertex, CNN x iecenc ened do.dctnn cE tdk Wadd anata eee hGe Gear ard awiet oeoeaneats 15
of head of honey bee.........2..-0- 02 eee eee eee eee ec eee eee ence 29
Vesiculee seminales..............--. pik eeee SSS haba pad sae haecranweaeeeas 132
Wax Glaiids ..cncccsturs ahh abhanno ante conin aubohbnheanonmencedeeasu enced 71
BOCEG LL OL aja aor canbe trta eveesyns ane cd arnt eave onc nw pvr esaeats Speansreveasi cielo hencvaveunaeataitclelouevs T1712
GNCAIS a22i5 scene ede e Ee eee She tece eee PREM ee ee s'sies ee ibale 68
Wing processes of notum, defined............-2.- 222.202. 2ece eee eee eee 19
of mesonotum of honey bee.................-..2.--. 62

metanotum of honey bee..............-.2...2.--- 56

22181—No. 18—10——11
162 THE ANATOMY OF THE HONEY BEE.

Page.

Wing processes of pleura, defined................0.020202002ce cece cence eee eee 19
of mesopleurum of honey hee............----------- 56

Wings, articulation in generalized insect..........2-2222-0-02e2eeee cece eee eee 23
NONE: DOC ize cpdecexiei: segiaefaw ec cuentsnsiiedte'd pattaciaetasts 62-63

COHN dit. gd neces cage eee aes to's eae taeee Oe lee luak tdeatsblel teats 13
MOLION spies eeu e egies oi ES Sha et tee ey ae ees 63
MUSCI CS v.05 seewevesseeee yess seed ech Gns eee seteeecedes ee eee te ea ees 63-66
of generalized insect...........--22-. 22-2202 eee cece cece cree tees patpentsa’ 22-24
None y PCC. coc hess dad oo ae ood aeioas oe a iiase ae ae eSaess 62-66
FLV MEN OPC cack cence io pees cenateidasasatekmenst te test ccsaes 59-62
pronator apparatus... ccs2.sscuewerseaesamemecanceumicanen ds MeH eas 2 65

VEMG tet ice tesecnedGe So oc yale: Sea avenenwtisteecee i eesat ete cess 59-62
Workers, defined....................-- Breech le ulichs bab Shatoh nied neainiarceieiesie ne Sie Se 130
HINGHONAN Hive sa.cvres serene s se seg poaeeeadsawemebenies ese 130-131
U.S. DEPARTMENT OF AGRICULTURE,
BUREAU OF ENTOMOLOGY—BULLETIN No. 121.

L, O. HOWARD, Entomologist and Chief of Bureau.

THE BEHAVIOR OF THE HONEY BEE
IN POLLEN COLLECTING.

BY

D. B. CASTEEL, Pu. D.,

Collaborator and Adjunct Professor of Zoology,
University of Texas.

Issurep December 31, 1912.

 

WASHINGTON:
GOVERNMENT PRINTING OFFIOE.
1912.
BUREAU OF ENTOMOLOGY.

L, O. Howarp, Entomologist and Chief of Bureau.
C. L. MarLatr, Entomologist and Acting Chief in Absence of Chief.
R. S. Ciirron, Heecutive Assistant.
W. F. Tastet, Chief Clerk.

F. H. CHITTENDEN, in charge of truck crop and stored product insect investigations.
A. D. HopxKins, in charge of forest insect investigations.

W. D. Hunter, in charge of southern field crop insect investigations.

F. M. WEssTER, in charge of cereal and forage insect investigations.

A. L. QUAINTANCE, in charge of deciduous fruit insect investigations.

E. F. Putiiirs, in charge of bee culture.

D. M. Rogers, in charge of preventing spread of moths, field work.
Roizta P. CurRig, in charge of editorial work.

MasBet Cotcorn, in charge of library.

INVESTIGATIONS IN BEE CULTURE.
EK. F. PHIuires, in charge.

G. F. Wuite, J. A, NELSON, experts.

G. 8. DemutuH, A. H. McCray, N. BE. McInpoo, apicultural assistants.
PEARLE H. GARRISON, preparator.

D. B. CASTEEL, collaborator,

2
LETTER OF TRANSMITTAL.

U. S. Department or AGRICULTURE,
Bureau or Entomotoey,
Washington, D. C., September 23, 1912.
Sir: I have the honor to transmit herewith a manuscript entitled
“ The Behavior of the Honey Bee in Pollen Collecting,” by Dr. Dana
B. Casteel, of this bureau. The value of the honey bee in cross pol-
linating the flowers of fruit trees makes it desirable that exact infor-
mation be available concerning the actions of the bee when gathering
and manipulating the pollen. The results recorded in this manu-
script are also of value as studies in the behavior of the bee and will
prove interesting and valuable to the bee keeper. The work here
recorded was done by Dr. Casteel during the summers of 1911 and
1912 at the apiary of this bureau. 5
I recommend that this manuscript be published as Bulletin No. 121
of the Bureau of Entomology.
Respectfully, L. O. Howarp,
Entomologist and Chief of Bureau.
Hon. James WItson,
Secretary of Agriculture.
 

CONTENTS:

IntroductiOtlanccccccasccccasseancan te ese tears dceimeeeameeeeeeeEe eS
The structures concerned in the manipulation of pollen...............-..----
The'pollensipPlyie..ncccccaseaveds nencas coats Se He eek eeana gE EELS
General statement of the pollen-collecting process..............-.---.--------
Action of the forelegs and mouthparts............2.-..2--2--2-2222- 222 eee eee
aor wn

 

ILLUSTRATIONS.

TEXT FIGURES.

. Left foreleg of a worker bee....-..--- 22-2202 e eee eee e eee ee cece eee
. Left middle leg of a worker bee...-....-.----.--.-0---0-202ee eee ee eee
. Outer surface of the left hind leg of a worker bee...-..-..--.---------
. Inner surface of the left hind leg of a worker bee..............-- ee
. A flying bee, showing the manner in which the forelegs and middle legs

manipulate: pollenia: wccteiris eae icciieine sew mie niereee arciecd > ogathewia eee ace

. A bee upon the wing, showing the position of the middle legs when they

touch and pat down the pollen masses........---.--------+--------

. A bee upon the wing, showing the manner in which the hind legs are

held during the basket-loading process. .

. The left hind legs of worker bees, showing hed manner in which: pollen

enters: the baskelvss-jesescus cena eet rote eda sesso akeeene ses

. Inner surface of the right hind leg of a worker bee which bears a com-

plete load of polletncscccesccecsevecsesess. eceviersetesecsaewesises
6

14

15

17

19
THE BEHAVIOR OF THE HONEY BEE IN POLLEN COLLECTING.

 

INTRODUCTION.

While working upon the problem of wax-scale manipulation dur-
ing the summer of 1911 the writer became convinced that the so-
called wax shears or pinchers of the worker honey bee have nothing
whatever to do with the extraction of the wax scales from their
pockets, but rather that they are organs used in loading the pollen
from the pollen combs of the hind legs into the corbicule or pollen
baskets (Casteel, 1912). Further observations made at that time dis-
closed the exact method by which the hind legs are instrumental in
the pollen-loading process and also the way in which the middle legs
aid the hind legs in patting down the pollen masses. During the
summer of 1912 additional information was secured, more particu-
larly that relating to the manner in which pollen is collected upon
the body and legs of the bee, how it is transferred to the hind legs,
how it is moistened, and finally the method by which it is stored in
the hive for future use. In the present paper a complete account will
be given of the history of the pollen from the time it leaves the flower
until it rests within the cells of the hive. The points of more par-
ticular interest in the description of pollen manipulation refer to
(1) the movements concerned in gathering the pollen from the
flowers upon the body and legs, (2) the method by which the baskets
of the hind legs receive the loads which they carry to the hive, and
(3) the manner in which the bee moistens pollen and renders it suf-
ficiently cohesive for packing and transportation.

THE STRUCTURES CONCERNED IN THE MANIPULATION OF
POLLEN.

The hairs which cover the body and appendages of the bee are of
the utmost importance in the process of pollen gathering. For the
purposes of this account these hairs may be classified roughly as
(1) branched hairs and (2) unbranched hairs, the latter including
both long, slender hairs and stiff, spinelike structures.

Of these two classes the branched hairs are the more numerous.
They make up the hairy coat of the head, thorax, and abdomen, with
the exception of short sensory spines, as those found upon the an-
tennz and perhaps elsewhere, and the stiff unbranched hairs which

7
8 BEHAVIOR OF HONEY BEE IN POLLEN COLLECTING.

cover the surfaces of the compound eyes (Phillips, 1905). Branched
hairs are also found upon the legs; more particularly upon the more
proximal segments. A typical branched hair is composed of a long
slender main axis from which spring numerous short lateral barbs.
Grains of pollen are caught and held in the angles between the axis
and the.barbs and between the barbs of contiguous hairs. The hairy
covering of the body and legs thus serves as a collecting surface upon
which pollen grains are temporarily retained and from which they
are later removed by the combing action of the brushes of the legs.

Although, as above noted, some unbranched hairs are located upon
the body of the bee, they occur in greatest numbers upon the more
distal segments of the appendages. They are quite diverse in form,
some being extremely long and slender, such as those which curve
over the pollen
baskets, others
being stout and
stiff, as those
which form the
collecting brushes
and the pecten

z+, spines.
dibe The mouth-
parts of the bee
are also essential
to the proper col-
lection of pollen.
The mandibles
are used to scrape
over the anthers
of flowers, and
considerable pollen adheres to them and is later removed. The.same
is true of the maxilla and tongue. From the mouth comes the fluid
by which the pollen grains are moistened.

The legs of the worker bee are especially adapted for pollen gath-
ering. Each leg bears a collecting brush, composed of stiff, un-
branched hairs set closely together. These brushes are located upon
the first or most proximal tarsal segment of the legs, known techni-
cally as the palme of the forelegs and as the plante of the middle
and hind pair. The brush of the foreleg is elongated and of slight
width (fig. 1), that of the middle leg broad and flat (fig. 2), while
the brush upon the planta of the hind leg is the broadest of all, and
is also the most highly specialized. In addition to these well-marked
brushes, the distal ends of the tibiz of the fore and middle legs bear
many stiff hairs, which function as pollen collectors, and the distal
tarsal joints of all legs bear similar structures.

 

Fic. 1.—Left foreleg of a worker bee. (Original.)
THE STRUCTURES CONCERNED. 9

The tibia and the planta of the hind leg of the worker bee are .
greatly flattened. (See figs. 3,4.) The outer surface of the tibia is
marked by an elongated depression, deepest at its distal end, and
bounded laterally by elevated margins. From the lateral boundaries
of this depression spring many long hairs, some of which arch over
the concave outer surface of the tibia and thus form a kind of recep-
tacle or basket to which the name corbicula or pollen-basket is given.
The lower or distal end of the tibia articulates at its anterior edge with
the planta. The remaining portion of this end of the tibia is flat-
tened and slightly concave, its
surface sloping upward from
the inner to the outer surface
of the limb. Along the inner
edge of this surface runs a row
of short, stiff, backwardly di-
rected spines, from 15 to 21 in
number, which form the pec-
ten or comb of the tibia. The
lateral edge of this area forms
the lower boundary of the
corbicular depression and is
marked by a row of very fine
hairs which branch at their
free ends. Immediately above
these hairs, springing from the
floor of the corbicula, are found
7 or 8 minute spines, and above
them one long hair which
reaches out over the lower edge
of the basket.

The broad, flat planta (meta-
tarsus or proximal tarsal seg-
ment of the hind leg) is marked
on its inner surface by several
rows of stiff, distally directed 16. 2.—Left middle leg of a worker bee.

a x (Oviginal.)
spines which form the pollen
combs. About 12 of these transverse rows may be distinguished,
although some of them are not complete. The most distal row, which
projects beyond the edge of the planta, is composed of very strong,
stiff spines which function in the removal of the wax scales (Casteel,
1912). The upper or proximal end of the planta is flattened and pro-
jects in a posterior direction to form the auricle. The surface of the
auricle is marked with short, blunt spines, pyramidal in form, and a
fringe of fine hairs with branching ends extends along its lateral edge.

This surface slopes upward and outward.
61799°—Bull. 121—12——-2

 
10 BEHAVIOR OF HONEY BEE IN POLLEN COLLECTING.
THE POLLEN SUPPLY.

When bees collect pollen from flowers they may be engaged in this
occupation alone or may combine it with nectar gathering. From
some flowers the bees take only nectar, from others only pollen; a
third class of flowers furnishes
an available supply of both of
these substances. But even
where both pollen and nectar
are obtainable a bee may
gather nectar and disregard
the pollen. This is well illus-
trated by the case of white
clover. If bees are watched
while working upon clover
flowers, the observer will soon
perceive some which bear pol-
len masses upon their hind
legs, while others will continue
to visit flower after flower,
dipping into the blossoms and
securing a plentiful supply of
nectar, yet entirely neglecting
the pollen.

The supply of pollen which
is available for the bees varies
greatly among different flow-
ers. Some furnish an abun-
dant amount and present it to
the bee in such a way that
little difficulty is experienced
in quickly securing an ample
load, while others furnish but
little. When flowers are small
and when the bee approaches
them from above, little, if any,
pollen is scattered over the

Zs bee’s body, all that it acquires
if being first collected upon the

 

ay mouth and neighboring parts.

Fre. 3.—Outer surface of the left hind leg. of a Very different conditions are
worker bee. (Original.)

met with when bees visit such

plants as corn and ragweed. The flowers of these plants are pendent

and possess an abundant supply of pollen, which falls in showers over

the bodies of the bees as they crawl. beneath the blossoms. The
GENERAL STATEMENT OF PROCESS. 11

supply of pollen which lodges upon the body of the bee will thus
differ considerably in amount, depending upon the type of flower
from which the bee is collecting, and the same is true regarding the
location upon the body of a bee of pollen grains which are available

for storage in the baskets.
Moreover, the movements
concerned in the collection
of the pollen from the va-
rious body parts of the
bee upon which it lodges
will differ somewhat in
the two cases, since a
widely scattered supply
requires for its collection
additional movements,
somewhat similar in na-
ture to those which the
bee employs in cleaning
the hairs which cover its
body.

/GENERAL STATEMENT
OF THE POLLEN-COL-
LECTING PROCESS.

A very complete knowl-
edge of the pollen-gather-
ing behavior of the worker
honey bee may be obtained
by a study of the actions
of bees which are work-
ing upon a plant which
yields pollen in abun-
dance. Sweet corn is an
ideal plant for this pur-
pose, and it will be used
as a basis for the descrip-
tion which follows.

In attempting to out-

line the method by which "™*

pollen is manipulated the

Paige

  
 

Auricle-

Pollen Combs lis

     

        
 

 

      
   

ph
epi idee NG
i
Uy fi HATA AEN in ,
Bit
1%)

Up iis

hy Ly!
hasty fi
f

   
      
 

entaly Win
MUU Mat ET
Mi
MAIN

vey

 
 

Wy

  
 
 
 
         
    

t,

4.—Inner surface of the left hind leg of a
werker bee. (Original.)

writer wishes it to be understood that he is recounting that which
he has seen and that the description is not necessarily complete,
although he is of the opinion that it is very nearly so. The move-
ments of the legs and of the mouthparts are so rapid and so many
12 BEHAVIOR OF HONEY BEE IN POLLEN COLLECTING.

members are in action at once that it is impossible for the eye to
follow all at the same time. However, long-continued observation,
assisted by the study of instantaneous photographs, gives confidence
that the statements recorded are accurate, although some movements
may have escaped notice.

To obtain pollen from corn the bee must find a tassel in the right
stage of ripeness, with flowers open and stamens hanging from them.
The bee alights upon a spike and crawls along it, clinging to the
pendent anthers. It ctawls over the anthers, going from one flower
to another along the spike, being all the while busily engaged in the
task of obtaining pollen. This reaches its body in several ways.

As the bee moves over the anthers it uses its mandibles and tongue,
biting the anthers and licking them and securing a considerable
amount of pollen upon these parts. This pollen becomes moist and
sticky, since it is mingled with fluid from the mouth. A considerable
amount of pollen is dislodged from the anthers as the bee moves over
them. All of the legs receive a supply of this free pollen and much
adheres to the hairs which cover the body, more particularly to those
upon the ventral surface. This free pollen is dry and powdery and
is very different in appearance from the moist pollen masses with
which the bee returns to the hive. Before the return journey this
pollen must be transferred to the baskets and securely packed in them.

After the bee has traversed a few flowers along the spike and has
become well supplied with free pollen it begins to collect it from its
body, head, and forward appendages and to transfer it to the pos-
terior pair of legs. This may be accomplished while the bee is
resting upon the flower or while it is hovering in the air before
seeking additional pollen. It is probably more thoroughly and rap-
idly accomplished while the bee is in the air, since all of the legs are
then free to function in the gathering process.

If the collecting bee is seized with forceps and examined after it
has crawled over the stamens of a few flowers of the corn, its legs
and the ventral surface of its body are found to be thickly powdered
over with pollen. If the bee hovers in the air for a few moments
and is then examined very little pollen is found upon the body or
upon the legs, except the masses within the pollen baskets. While in
the air it has accomplished the work of collecting some of the scat-
tered grains and of storing them in the baskets, while others have
been brushed from the body.

In attempting to describe ‘the movements by which this result is
accomplished it will be best first to sketch briefly the réles of the
three pairs of legs. They are as follows:

(a) The first pair of legs remove scattered pollen from the head
and the region of the neck, and the pollen that has been moistened
by fluid substances from the mouth.
ACTION OF FORELEGS AND MOUTHPARTS. 18

(6) The second pair of legs remove scattered pollen from the
thorax, more particularly from the ventral region, and they re-
ceived the pollen that has been collected by the first pair of legs.

(¢) The third pair of legs collect a little of the scattered pollen
from the abdomen and they receive pollen that has been collected
by the second pair. Nearly all of this pollen is collected by the
- pollen combs of the hind legs, and is transferred from the combs to
the pollen baskets or corbicule in a manner to be described later.

It will thus be seen that the manipulation of pollen is a succes-
sive process, and that most of the pollen at least passes backward
from the point where it happens to touch the bee until it finally
reaches the corbicule or is accidentally dislodged and falls from the
rapidly moving limbs.

ACTION OF THE FORELEGS AND MOUTHPARTS.

Although the pollen of some plants appears to be somewhat sticky,
it may be stated that as a general rule pollen can not be successfully
manipulated and packed in the baskets without the addition of some
fluid substance, preferably a fluid which will cause the grains to
cohere. This fluid, the nature of which will be considered later,
comes from the mouth of the bee, and is added to the pollen which
is collected by the mouthparts and to that which is brought into con-
tact with the protruding tongue and maxille, and, as will appear,
this fluid also becomes more generally distributed upon the legs and
upon the ventral surface of the collecting bee.

When a bee is collecting from the flowers of corn the mandibles are
actively engaged in seizing, biting, and scraping the anthers ag the
bee crawls over the pendent stamens. Usually, but not always, the
tongue is protruded and wipes over the stamens, collecting pollen

-and moistening the grains thus secured. Some of the pollen may
possibly be taken into the mouth. AII of the pollen which comes in
contact with the mouthparts is thoroughly moistened, receiving more
fluid than is necessary for rendering the grains cohesive. This
exceedingly wet pollen is removed from the mouthparts by the fore-
legs (fig. 5), and probably the middle legs also secure a little of it
directly, since they sometimes brush over the lower surface of the
face and the mouth. In addition to removing the very moist pollen
from the mouth the forelegs also execute cleansing movements ‘over
the sides of the head and neck and the anterior region of the thorax,
thereby collecting upon their brushes a considerable amount of pollen
which has fallen directly upon these regions, and this is added to the
pollen moistened from the mouth, thereby becoming moist by contact.
The brushes of the forelegs also come in contact with the anterior
breast region, and the hairs which cover this area become moist with
the sticky exudation which the forelegs have acquired in the process
of wiping pollen from the tongue, maxillz, and mandibles.
14 BEHAVIOR OF HONEY BEE IN POLLEN COLLECTING.

ACTION OF THE MIDDLE LEGS.

The middle legs are used to collect the pollen gathered by the
forelegs and mouthparts, to remove free pollen from the thoracic
region, and to transport their load of pollen to the hind legs, placing
most of it upon the pollen combs of these legs, although a slight
amount is directly added to the pollen masses in the corbicule. Most
of the pollen of the middle legs is gathered upon the conspicwous
brushes of the first tarsal segments or plante of these legs.

In taking pollen from a foreleg the middle leg of the same side is ex-
tended in a forward direction and is either grasped by the flexed fore-
leg or rubbed over the foreleg as it is bent downward and backward.
In the former movement the foreleg flexes sharply upon itself until

 

Fie. 5.—A flying bee, showing the manner in which the forelegs and middle legs manipu-
Jate pollen. The forelegs are removing wet pollen from the mouthparts and face. The
middle leg of the right side is transferring the pollen upon its brush to the pollen
combs of the left hind planta. A small amount of pollen has already been placed in
the baskets. (QOriginal.)

the tarsal brush and coxa nearly meet. The collecting brush of the
middle leg is now thrust in between the tarsus and coxa of the fore-
leg and wipes off some of the pollen from the foreleg brush. The
middle leg brush is then raised and combs down over the flexed fore-
leg, thus removing additional pollen from the outer surface of this
leg. The middle leg also at times reaches far forward, stroking down
over the foreleg before it is entirely flexed and apparently combing
over with its tarsal brush the face and mouthparts themselves.
When the middle leg reaches forward to execute any of the above
movements the direction of the stroke is outward, forward, and then
back toward the body, the action ending with the brush of the leg in
contact with the long hairs of the breast and with those which spring
ACTION OF MIDDLE LEGS. 15

from the proximal segments of the forelegs (coxa, trochanter,
femur). As a result of the oft-repeated contact of the brushes of
the middle and forelegs with the breast, the long, branched hairs
which cover this region become quite moist and sticky, since the
brushes of these two pair of legs are wet and the pollen which they
bear possesses a superabundance of the moistening fluid. Any dry
pollen which passes over this region and touches these hairs receives
moisture by contact with them. This is particularly true of the free
dry pollen which the middle pair of legs collect by combing over the
sides of the thorax.

The pollen upon the middle legs is transferred to the hind legs in
at least two ways. By far the larger amount is deposited upon the
pollen combs which lie on the inner surfaces of the plante of the

 

Fig. 6.—A bee upon the wing, showing the position of the middle legs when they touch
and pat down the pollen masses. A very slight amount of pollen reaches the corbicule
through this movement. (Original.)

hind legs. To accomplish this a middle leg is placed between the
plante of the two hind legs, which are brought together so as to grasp
the brush of the middle leg, pressing it closely between them, but
allowing it to be drawn toward the body between the pollen combs
of the two hind legs. (See fig. 5.) This action results in the trans-
ference of the pollen from the middle-leg brush to the pollen combs
of the hind leg of the opposite side, since the combs of that leg scrape
over the pollen-laden brush of the middle leg. This action may take
place while the bee is on the wing or before it leaves the flower.

The middle legs place a relatively small amount of pollen directly
upon the pollen masses in the corbicule. This is accomplished when
the brushes of the middle legs are used to pat down the pollen masses
and to render them more compact. (See fig.6.) The legs are used —
16 BEHAVIOR OF HONEY BEB IN POLLEN COLLECTING.

for this purpose quite often during the process of loading the baskets,
and a small amount of pollen is incidentally added to the masses
when the brushes come into contact with them. A misinterpretation
of this action has led some observers into the erroneous belief that
all or nearly all of the corbicular pollen is scraped from the middle-
leg brushes by the hairs which fringe the sides of the baskets. The
middle legs do not scrape across the baskets, but merely pat down-
ward upon the pollen which is there accumulating.

It is also possible that, in transferring pollen from the middle leg
of one side to the planta of the opposite hind leg, the middle-leg
brush may touch and rub over the pecten of the hind leg and thus
directly place some of its pollen behind the pecten spines. Such a
result is, however, very doubtful.

ACTION OF THE HIND LEGS.

The middle legs contribute the.major portion of the pollen which
reaches the hind legs, and all of it in cases where all of the pollen
first reaches the bee in the region of the mouth. However, when
much pollen falls upon the body of the bee the hind legs collect a
little of it directly, for it falls upon their brushes and is collected
upon them when these legs execute cleansing movements to remove
it from the ventral surface and sides of the abdomen. All of the
pollen which reaches the corbicule, with the exception of the small
amount placed there by the middle legs when they pat down the
pollen masses, passes first to the pollen combs of the plante.

When in the act of loading’ pollen from the plantar brushes to the
corbicule the two hind legs hang beneath the abdomen with the tibio-
femoral joints well drawn up toward the body. (See fig. 7.) The
two plantz lie close together with their inner surfaces nearly parallel
to each other, but not quite, since they diverge slightly at their distal
ends. The pollen combs of one leg are in contact with the pecten
comb of the opposite leg. If pollen is to be transferred from the
right planta to the left basket, the right planta is drawn upward in
such a manner that the pollen combs of the right leg scrape over
the pecten spines of the. left. By this action some of the pollen is
removed from the right plantar combs and is caught upon the outer
surfaces of the pecten spines of the left leg.

This pollen now lies against the pecten and upon the flattened
distal end of the left tibia. At this moment the planta of the left
leg is flexed slightly, thus elevating the auricle and bringing the auri-
cular surface into contact with the pollen which the pecten has just
received. By this action the pollen is squeezed between the end of the
tibia and the surface of the auricle and is forced upward against the
distal end of the tibia and on outward into contact with the pollen

.Mass accumulating in the corbicula. As this act, by which the left
ACTION OF HIND LEGS. 17

basket receives a small contribution of pollen, is being completed, the
right leg is lowered and the pecten of this leg is brought into contact
with the pollen combs of the left planta, over which they scrape as
the left leg is raised, thus depositing pollen upon the lateral surfaces
of the pecten spines of the right leg. (See fig. 7.)

Right and left baskets thus receive alternately successive contribu-
tions of pollen from the planta of the opposite leg. These loading
movements are executed with great rapidity, the legs rising and fall-
ing with a pump-like motion. A very small amount of pollen is
loaded at each stroke and many strokes are required to load the
baskets completely. \

If one attempts to obtain, from the literature of apiculture and
zoology, a knowledge of the method by which the pollen baskets

 

Fig. 7—A bee upon the wing, showing the manner in which the hind legs are held during
the basket-loading process. Pollen is being scraped by the pecten spines of the right
leg from the pollen combs of the left hind planta. (Original.)

themselves are loaded, he is immediately confused by the diversity of

the accounts available. The average textbook of zoology follows

closely Cheshire’s (1886) description in which he says that “the legs
are crossed, and the metatarsus naturally scrapes its comb face on the
upper edge of the opposite tibia in the direction from the base of the
combs toward their tips. These upper hairs * * * are nearly
straight, and pass between the comb teeth. The pollen, as removed,
is caught by the bent-over hairs, and secured. Each scrape adds to
the mass, until the face of the joint is more than covered, and the
hairs just embrace the pellet.” Franz (1906) states that (translated)
“ the final loading of the baskets is accomplished by the crossing over
of the hind-tarsal segments, which rub and press upon each other.”
_Many other observers and textbook writers evidently believed that
the hind legs were crossed in the loading process.
61799°—Bull. 121—12 3

 
18 BEHAVIOR OF HONEY BEE IN POLLEN COLLECTING.

On the other hand, it is believed by some that the middle legs are
directly instrumental in filling the baskets. This method is indicated
in the following quotation from Fleischmann and Zander (1910)
(translated) :

The second pair of legs transfer the pollen to the hind legs, where it is
heaped up in the pollen masses. The tibia of each hind leg is depressed on its
outer side, and upon the edges of this depression stand two rows of stiff hairs
which are bent over the grooye. The brushes of the middle pair of legs rub
over these hairs, liberating the pollen, which drops into the baskets.

A suggestion of the true method is given by Hommell (1906),
though his statements are somewhat indefinite. After describing
the method by which pollen is collected, moistened, and passed to
the niiddle legs he states that. (translated) “the middle legs place
their loads upon the pollen combs of the hind legs. There the sticky
pollen is kneaded and is pushed across the pincher (4 traverse la
pince), is broken up into little masses and accumulates within the
corbicula. In accomplishing this, the legs cross and it is the tarsus
of the right leg which pushes thé pollen across the pincher of the
left, and reciprocally. The middle legs never function directly in
loading the baskets, though from time to time their sensitive ex-
tremities touch the accumulated mass, for the sake of giving assur-
ance of its position and size.”

The recent valuable papers of Sladen (1911, 1912, a, b,c, d, and e),
who was the first to present a true explanation of the function of
the abdominal scent gland of the bee, give accounts of the process
by which the pollen baskets are charged, which are in close accord
with the writer’s ideas on this subject. It is a pleasure to be able to
confirm most of Sladen’s observations and conclusions, and weight is
added to the probable correctness of the two descriptions and in-
terpretations of this process by the fact that the writer’s studies and
the conclusion based upon them were made prior to the appearance
of Sladen’s papers and quite independent of them. His description
of the basket-loading process itself is so similar to the writer’s own
that a complete quotation from him is unnecessary. A few differences
of opinion will, however, be noted while discussing some of the move-
ments which the process involves. As will later be noted, our ideas
regarding the question of pollen moistening, collecting, and transfer-
ence are somewhat different.

ADDITIONAL DETAILS OF THE BASKET-LOADING PROCESS.

The point at which pollen enters the basket can best be determined
by examining the corbicule of a bee shortly after it has reached a
flower and before much pollen has been collected. Within each
pollen basket of such a bee is found a small mass of pollen, which lies
ADDITIONAL DETAILS OF BASKET-LOADING PROCESS. 19

along the lower or distal margin of the basket. (See fig 8, a.) It is
in this position because it has been scraped from the planta of the
opposite leg by the pecten comb and has been pushed upward past
the entrance of the basket by the continued addition of more from
below, propelled by the successive strokes of the auricle. Closer

    
 

    

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A A's
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iy

    

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Fic. 8.—Camera drawings of the left hind legs of worker bees to show the manner in
which pollen enters the basket. a, Shows a leg taken from a bee which is just begin-
ning to collect. It had crawled «ver a few flowers and bad flown in the air about five
seconds at the time of capture. The pollen mass lies at the entrance of the basket,
covering over the fine hairs which lie along this margin and the seven or eight short
stiff spines which spring from the floor of the corbicula immediately above its lower
edge. As yet the pollen has not come in contact with the one long hair which rises

‘ fron; the floor and arches over the entrance. ‘The planta is extended, thus lowering
the auricle; b, represents a slightly later stage, showing the increase of pollen. The
planta is flexed, raising the auricle. ‘The hairs which extend outward and upward from
the lateral edge of the auricle press upon the lower and outer surface of the small
pollen mass, retaining it and guiding it upward into the basket; ¢, d, represent slightly
later stages in the successive processes by which additional pollen enters the basket.
(Original.)

examination of the region between the pecten and the floor of the
basket itself shows more pollen, which is on its way to join that
already squeezed into the basket.

If the collecting bee is watched for a few moments the increase will
readily be noted and the fact will be established that the accumulat-
ing mass is gradually working upward or proximally from the lower
20 BEHAVIOR OF HONEY BEE IN POLLEN COLLECTING.

or distal edge of the corbicula and is slowly covering the floor of this
receptacle. (See fig. 8, 6, c, and d.) In many instances the suc-
cessive contributions remain for a time fairly separate, the whole
mass being marked by furrows transverse to the long axis of the tibia.

Sladen (1912, &) notes the interesting fact that in those rather
exceptional cases when a bee gathers pollen from more than one
species of flowers the resulting mass within the corbicula will show
a stratification parallel to the distal end, a condition which could
result only from the method of loading here indicated.

As the pollen within the basket increases in amount it bulges out-
ward, and projects downward below the lower edge of the basket.
It'is held in position by the long hairs which fringe the lateral sides
of the basket, and its shape is largely determined by the form of
these hairs and the direction in which they extend. When the basket
is fully loaded the mass of pollen extends laterally on both sides of
the tibia, but projects much farther on the posterior side, for on this
side the bounding row of hairs extends outward, while on the anterior
edge the hairs are more curved, folding upward and over the basket.
As the mass increases in thickness by additions from below it is held
in position by these long hairs which edge the basket. They are
pushed outward and many of them become partly embedded in the
pollen as it is pushed up from below. When the pollen grains are
small and the whole mass is well moistened the marks made by some
of the hairs will be seen on the sides of the load. (See fig. 9, a.)
These scratches are also transverse in direction and they show that
the mass has been increased by additions of pollen pushed up from
below.

Even a superficial examination of a heavily laden basket shows
the fallacy of the supposition that the long lateral fringing hairs are
used to comb out the pollen from the brushes of either the hind or
middle legs by the crossing of these legs over the lateral edges of the
baskets. They are far from sufficiently stiff to serve this purpose,
and their position with relation to the completed load shows con-
clusively that they could not be used in the final stages of the loading
process, for the pollen mass has completely covered many of them
and its outer surface extends far beyond their ends. They serve
merely to hold the pollen in place and to allow the load to project
beyond the margins of the tibia.

‘The auricle plays a very essential part in the process of loading
the basket. This structure comprises the whole of the flattened
proximal surface of the planta, except the joint of articulation itself,
and it extends outward in a posterior direction a little beyond the
remaining plantar edge. The surface of the auricle is covered over
with many blunt, short spines and its lateral margin is bounded by
a row of short rather pliable hairs, branched at their ends. When
ADDITIONAL DETAILS Of BASKET-LOADING PROCESS. 91

the planta is flexed the auricle is raised and its surface approaches
the distal end of the tibia, its inner edge slipping up along the pecten
spines and its outer hairy edge projecting into the opening which
leads to the pollen basket. (See fig. 8,6.) With each upward stroke
of the auricle small masses of pollen which have been scraped from the
plantar combs by the pecten are caught and compressed between the
spiny surface of the auricle and the surface of the tibia above it.
The pressure thus exerted forces the pasty pollen outward and up-
ward, since it can not escape past the base of the pecten, and directs
it into the entrance to the corbicula. The outward and upward slant
of the auricular surface and the projecting hairs with which the outer
edge of the auricle is supplied also aid in directing the pollen toward
the basket. Sladen (1911) states that in this movement the weak
wing of the auricle is forced backward, and thus allows the escape of
pollen toward the basket entrance, but this appears both doubtful and
unnecessary, since the angle of inclination of the auricular surface
gives the pollen a natural outlet in the proper direction.

If the corbicula already contains a considerable amount of pollen
the contributions which are added to it at each stroke of the auricle
come in contact'with that already deposited and form a part of this
mass, which increases in amount by continued additions from below.
If, however, the corbicula is empty and the process of loading is just
beginning, the first small bits of pollen which enter the basket must
be retained upon the floor of the chamber until a sufficient amount
has accumulated to allow the long overcurving hairs to offer it effec-
tive support. The sticky consistency of the pollen renders it likely
to retain contact with the basket, and certain structures near the
entrance give additional support. Several small sharp spines, seven
or eight in number, spring from the floor of the basket immediately
within the entrance, and the entire lower edge of the corbicula is
fringed with very small hairs which are branched at their ends.
(See fig. 3.) One large hair also springs from the floor of the basket,
somewhat back from the entrance, which may aid in holding the
pollen, but it can not function in this manner until a considerable
amount has been collected.

As the pollen mass increases in size and hangs downward and back-
ward over the pecten and auricle it shows upon its inner and lower
surface a deep groove which runs outward from the entrance to the
basket. (See fig. 9, 0.) This groove results from the continued im-
pact of the outer end of the auricle upon the pollen mass. At each
upward stroke of the auricle its outer point comes in contact with
the stored pollen as soon as the mags begins to bulge backward from
the basket.

Although the process is a rather delicate one, it is entirely pos-
sible so to manipulate the hind legs of a recently killed bee that the
22 BEHAVIOR OF HONEY BEE IN POLLEN COLLECTING.

corbicule of the two legs receive loads of pollen in a manner similar
to that above described. To accomplish this successfully the operator
must keep the combs of the plantz well supplied with moistened
pollen. If the foot of first one leg and then the other is grasped
with forceps and so guided that the pollen combs of one leg rasp over
the pecten spines of the other, the pollen from the combs will be
transferred to the corbicula. To continue the loading process in a
proper manner, it is also nec-
essary to flex the planta of
each leg just after the pollen
combs of the opposite leg
have deposited pollen behind
the pecten. By this action
the auricle is raised, com-
pressing the pollen which
the pecten has secured, and
forcing some upward into
the corbicula. Bees’ legs
which have been loaded in
this artificial manner show
pollen masses in their cor-
bicule which are entirely
similar in appearance to
those formed by the labors
of the living bee. More-
over, by the above method
of manipulation the pollen

 

 

im appears first at the bottom
p of the basket, along its lower
dj margin, gradually extends

upward along the floor of
Fig. 9.—Inner surface of the right hind leg of a the chamber, comes in con-

worker bee which bears a complete load of 5 *
pollen. a, Scratches in the pollen mass caused tact with the overhanging

by the pressure of the long projecting hairs hairs, and is shaped by them

of the basket upon the pollen mass as it has’ ;
been pushed up from below; 0, groove in the im a2 natural manner. Al 1

pollen mass made by the strokes of the auricle attempts to load the baskets

re mas penis ouemard and tACEW=rG by o¢her movements, such as

crossing the hind legs and

scraping the plantar combs over the lateral edges of the baskets,

give results which are entirely different from those achieved by the
living bee.

POLLEN MOISTENING.
Many descriptions have been written by others of the method by

which pollen is gathered and moistened. Some of these are indefi-
nite, some are incorrect, while others are, in part, at least, similar
POLLEN MOISTENING. 23

to my own interpretation of this process. A few citations will here
be given:

The bee first strokes the head and the proboscis with the brushes of the
forelegs and moistens these brushes with a little honey from the proboscis, so
that with later strokes all of the pollen from the head is collected upon these
brushes. Then the middle-leg brushes remove this honey-moistened pollen from
the forelegs and they also collect pollen from the breast and the sides of the
thorax.—[Translation from Alefeld, 1861.]

In his account of the basket-loading process Alefeld assigns to
the middle-leg brushes the function of assembling all of the pollen,
even that from the plantar combs, and of placing it on the corbicule,
this latter act being accomplished by combing over the hairy edge of
each basket with the middle-leg brush of the same side.

It appears probable that the bee removes the pollen from the head, breast,
and abdomen by means of the hairy brushes which are located upon the medial
sides of the tarsal segments of all of the legs, being most pronounced upon the
hind legs. The pollen is thus brought together and is carried forward to the
mouth, where it is moistened with saliva and a little honey.—[Translation from
Frauz, 1906.]

Franz then says that this moistened pollen is passed backward and
loaded.

Since the pollen of many plants is sticky and moist it adheres to the surface
of the basket. Dry pollen is moistened by saliva, so that it also sticks.—
[Translation from Fleischmann and Zander, 1910.]

Pollen is taken from flowers principally by means of the tongue, but at times,
also, by the mandibles, by the forelegs, and middle legs. The brushes of the
hind legs also load themselves, collecting from the hairs of the body: ‘The pollen
dust thus gathered is always transmitted to the mouth, where it is mixed with
saliva.—[Translation from Hommell, 1906.]

Sladen considers the question of how pollen is moistened by the
honey bee, humblebee (bumblebee), and some other bees, but does not
appear to reach definite conclusions. In one of his papers (1912, c)
he states that the pollen of some plants may be found in the mouth
cavity and in the region of the mouth, but he reaches the conclusion
that this pollen is comparatively “ dry,” using the word in a “ rela-
tive sense.” He asserts that “nowhere but on the corbicula and
hind metatarsal brushes did I find the sticky pollen, except some-
times on the tips of the long, branched haies on the back (upper)
edges of the tibiee and femora of the middle legs, and then only
in heavily laden bees, where it is reasonable to suppose it had
collected accidentally as the result of contact with the hind metatarsal
brushes.”

These and other considerations lead Sladen to think that, in the
case of the bumblebee at least, the pollen “ may be moistened on the
hind metatarsus with the tongue.” He states that the tongue of
the bumblebee is of sufficient length to reach the hind metatarsus
94 BEHAVIOR OF HONEY BEE IN POLLEN COLLECTING.

(planta) and that it might rub over the brushes of the metatarsi
or be caught between them when they are approximated and thus
moisten the two brushes simultaneously. However, he has never
seen the tongue of the ccllecting honey bee brought near to the hind
legs, and it appears probable to him that it can not easily reach them.
“ Possibly the middle or front legs are used as agents for conveying
the honey” (in the case of the honey bee). “In the humblebee the
tongue is longer, and it could more easily moisten the hind legs in
the way suggested.”

In an earlier paper Sladen (1912, a) gives the following as his
opinion of the “ way in which pollen dust is'‘moistened with nectar,”
although he states that this is one of the points “ which still remains
obscure ”:

The only satisfactory manner in which, it seems to me, this can be done is
for the tongue to lick the tarsi or metatarsi of the forelegs, which are covered
with stiff bristles, well suited for holding the nectar, the nectar being then
transferred to the metatarsal brushes on the middle legs, and from these, again,
to the metatarsal brushes on the hind legs. The latter being thus rendered
sticky, the pollen dust would cling to them. The different pairs of legs were
certainly brought together occasionally, but not after every scrape of the
hind metatarsi, and their movements were so quick that it was impossible
to see what was done. Still, several pollen-collecting bees that I killed had the
tarsi and metatarsi of the forelegs and the metatarsal brushes of the middle
and hind legs moistened with nectar, and I think it probable that the moisten-
ing process, as outlined, is performed, as a rule, during the flight from flower
to flower.

Sladen (1912, c) also considers the possibility that the fluid which
moistens the pollen might be secreted through the comb at the end
of the tibia, through the tibio-tarsal joint, or from the surface of the
auricle, but finds no evidence of glandular openings in these regions.
A suggestion of a similar nature, apparently unknown to Sladen,
was made by Wolff (1873), who describes “sweat-glands ” which,
he claims, are located within the hind tibia and the planta, and
which pour a secretion upon the surface of the corbicula and upon
the upper end of the planta through many minute openings located
at the bases of hairs, particularly those which arise from the lateral
margins of the corbicula. Wolff is convinced that the fluid thus
secreted is the essential, cohesive material by which the grains of
pollen are bound together to form the solid mass which fills each
fully loaded basket. He noticed that the mouthparts are used to
collect pollen, and that some of it is moistened with “honey” or
“nectar,” but he does not consider that the fluid thus supplied is
sufficient to explain adequately the facility with which the collecting
bee brings together the scattered grains of pollen and packs them
away securely in the baskets. Wolff’s description of the basket-load-
ing process itself is strikingly similar to that advocated later by
Cheshire.
POLLEN MOISTENING. 25

The writer is not prepared to deny the possibility that the surface
of the chitin of the hind legs of worker bees may be moistened by
the secretion of glands which lie beneath it, but he is convinced that
any fluid thus secreted bears little or no relation to the cohesion of
the pollen grains within the baskets. Sections and dissected prepa-
rations of the hind legs of worker bees show certain large cells which
lie within the cavity of the leg and which may function as secreting
gland cells; but similar structures occur in even greater numbers
within the hind legs of the drone and they are found within the hind
legs of the queen.

As has been noted, the extreme moisture of the plantar combs and
of the tibio-tarsal articulation of the hind leg is readily understood
when one recalls the manner in which moist pollen is compressed
between the auricle and the tibial surface above it.

From the account already given it is evident that, in the opinion
of the writer, the mouth is the source from which the pollen-moisten-
ing fluid is obtained. It is extremely difficult to determine with
absolute accuracy the essential steps involved in the process of adding
moisture to the pollen. In an endeavor to solve this problem the
observer must of necessity consider a number of factors, among which
may be noted (1) the location upon the body of the collecting bee
of “moist” and of comparatively “dry” pollen, (2) the movements
concerned in the pollen-gathering and pollen-transferring processes,
(8) the relative moisture of those parts which handle pollen, (4) the
chemical differences between the natural pollen of the flower and
that of the corbicule and of the cells of the hive, and (5) the observer
must endeavor to distinguish between essential phenomena and those
which are merely incidental or accidental.

In the first place it should be noted that the relative dampness of
pollen within the corbicule depends very largely upon the character
of the flower from which the pollen grains are gathered. When
little pollen is obtained it is much more thoroughly moistened, and
this is particularly true in cases when the pollen is all, or nearly all, .
collected in the region of the mouth, the forelegs, and head. When
a bee takes pollen from white or sweet clover practically all of it
first touches the bee in these regions. It immediately becomes moist,
and in this condition is passed backward until it rests within the
baskets. There is here no question of “dry” and “wet” pollen,
or of collecting movements to secure dry pollen from other regions
of the body, or of the ultimate method by which such free, dry pol-
len becomes moist.

The sticky fluid which causes pollen grains to cohere is found upon
all of the legs, in the region of their brushes, although the pollen
combs and auricles of the hind legs are likely to show it in greatest
abundance, since nearly all of the pollen within each basket has
26 BEHAVIOR OF HONEY BEE IN POLLEN COLLECTING.

passed over the auricle, has been pressed upward and squeezed be-
tween the auricle and the end of the tibia and the pollen mass above,
and by this compression has lost some of its fluid, which runs down
over the auricle and onto the combs of the planta. It is not necessary
to invoke any special method by which these areas receive their
moisture. The compressing action of the auricle squeezing heavily
moistened pollen upward into the basket is entirely sufficient to
account for the abundance of sticky fluid found in the neighborhood
of each hind tibio-tarsal joint. As has been noted, the brushes of
the forelegs acquire moisture directly by stroking over the proboscis
and by handling extremely moist pollen taken from the mouthparts.
The middle-leg brushes become moist by contact with the foreleg and
hind-leg brushes, probably also by touching the mouthparts them-
selves, and by passing moist pollen backward. The hairy surface of
the breast is moistened by contact with the fore and mid leg brushes
and with the moist pollen which they bear.

The problem of the method of pollen moistening is somewhat more
complicated in the case of flowers which furnish an excessive supply.
Under such conditions the entire ventral surface of the collecting bee
becomes liberally sprinkled with pollen grains which either will be
removed and dropped or will be combed from the bristles and branch-
ing hairs, kneaded into masses, transferred, and loaded. The ques-
tion naturally arises whether the movements here are the same as
when the plant yields but a small amount of pollen which is collected
by the mouthparts and anterior legs. In the opinion of the writer
they are essentially the same, except for the addition of cleansing
movements, executed chiefly by the middle and hind legs for the col-
lection of pollen which has fallen upon the thorax, upon the abdomen,
and upon the legs themselves. Indeed it is questionable as to just
how much of this plentiful supply of free pollen is really used, in
forming the corbicular masses. Without doubt much of it falls from
the bee and is lost, and in cases where it is extremely abundant and
the grains are very small in size an appreciable amount still remains
entangled among the body-hairs when the bee returns to the hive.
Yet it is also evident that some of the dry pollen is mingled with the
moistened material which the mouthparts and forelegs acquire and
together with this is transferred to the baskets.

In all cases the pollen-gathering process starts with moist pollen
from the mouth region. This pollen is passed backward, and in its
passage it imparts additional moisture to those body regions which
it touches, the brushes of the fore and middle legs, the plantz of the
hind legs, and the hairs of the breast which are scraped over by the
fore and middle leg brushes. This moist pollen, in its passage back-
ward, may also pick up and add to itself grains of dry pollen with
which it accidentally comes in contact. Some of the free, dry pollen
POLLEN MOISTENING. 24

which falls upon the moist brushes or upon the wet hairs of the
thorax is also dampened. Some of the dry pollen which is cleaned
from the body by the action of all of the legs meets with the wet
brushes or with the little masses of wet pollen and itself becomes wet
by contact. Pollen grains which reach the corbicule either dry or .
but slightly moistened are soon rendered moist by contact with those
already deposited. Little pollen gets by the sticky surfaces of the
combs of the plant or past the auricles without becoming thoroughly
moist.

Sladen (1912, c) very aptly compares the mixture of dry pollen
with wet to the kneading of wet dough with dry flour and suggests
that the addition of dry pollen may be of considerable advantage,
since otherwise the brushes, particularly those of the hind legs,
would become sticky, “just as the board and rolling pin get sticky
in working up a ball of dough if one does not add flour.” The addi-
tion of a considerable amount of dry pollen gives exactly this result,
for the corbicule then rapidly become loaded with pollen mixed
with a minimum supply of moisture and the brushes remain much
dryer than would otherwise be the case. However, if too much dry
pollen is added the resulting loads which the bees carry back to the
hives are likely to be irregular, for the projecting edges of the masses
may crumble through lack of a sufficient amount of the cohesive
material by which the grains are bound together.

On the other hand, it does not appear at all necessary to mix much
dry pollen with the wet, nor do the brushes become sufficiently
“sticky ” from the presence of an abundance of the moistening fluid
to endanger their normal functional activity. I have observed bees
bringing in pollen masses which were fairly liquid with moisture,
and the pollen combs also were covered with fluid, yet the baskets
were fully and symmetrically loaded.

Sladen’s different interpretations of the pollen-moistening process
are rather confusing, and it is difficult to distinguish between what
he states as observed facts and what he puts forward as likely
hypotheses. He agrees with me in his observation that all of the
legs become moist in the region of their brushes and also in his sup-
position that this moisture is transferred to them from the mouth.
In this moistening process my observations show that the fluid con-
cerned is passed backward by the contact of the middle-leg brushes
with the wet foreleg brushes and that the middle-leg brushes in turn
convey moisture to the plants as they rub upon them. I am also
convinced that the wet pollen grains furnish additional moisture to
the brushes as they pass backward, and this is particularly true in
the case of the extremely moist surfaces of the auricles and the pollen
combs of the planta, since here moisture is pressed from the pollen
upon these areas. The pollen upon the fore and middle leg brushes
is not always “ dry ” even in “a relative sense.”
28 BEHAVIOR OF HONEY BEE IN POLLEN COLLECTING.

In describing pollen manipulation several writers state that dry
pollen is picked up by the brushes of the legs and is carried forward
to the mouth, there moistened (according to some, masticated), and
is then carried backward by the middle legs for loading. Obviously
such accounts do not apply to cases in which all of the pollen is col-
lected by mouthparts and forelegs. Do they apply in cases where
much pollen falls on the body and limbs? Without doubt a certain
amount of this free pollen is brought forward when the middle legs,
bearing some of it, sweep forward and downward over the forelegs,
mouthparts, and breast. However, it does not appear to the writer
that this dry pollen is carried to the mouth for the specific purpose of
moistening it, or that it is essential to its moistening that it be
brought in contact with the mouth. Some of it touches the moist
hairs on the forelegs and breast and is moistened by contact. All
that remains on the brushes of the middle legs secures moisture from
these brushes or from -wet pollen which the brushes collect from the
mouthparts or forelegs. The supposed necessity of carrying forward
pollen to the mouth for moistening is a delusion. Some is acci-
dentally brought forward and into contact with the mouth and gets
wet, but the process is not essential.

If the pollen which bees transport to their hives has been moistened
with some fiuid substance which causes the grains to cohere, this
addition should be indicated by differences in the results of an analy-
sis of pollen from a plant as compared with that found in the cor-
bicule of a bee which has been working on this plant. For the sake
of determining this difference and in an endeavor to ascertain, if
possible, the approximate nature of the added fluid, analyses were
made of three kinds of pollen, as follows: (1) Pollen collected by
hand from the corn plant itself; (2) pollen taken from the corbicule
of bees which had secured their supply from corn; (3) pollen stored
in the cells of the hive. In the first two cases pollen from the same
species of plant (corn) was used. The material from the cells of the
hive was composed largely of corn pollen, but contained an admixture
of some other pollens.

The writer is indebted to Dr. P. B. Dunbar, of the Bureau of
Chemistry, for the following analyses:

 

 

 

 

 

Pollen Stored
direct | COP POL] poten
from boas from
corn, hive.
TOG SOLAS. cua occ jois dicisinysesdiccems aad ornaricmerniaeciec nsbiaate Hipeisisis a eS 53, 47 66. 94 79. 66
MOL SEUREG acct cscs esas eee ane ecorsieyst ce si navonsioitenesatsieldr sig etecctoieicices her 46. 53 33.06 20.34
Reducing sugar before inversion sie 2 2. 87 11.07 17.90
Bue r Og: is cje.c isssrsaisisiar aye ermine storie deere micereioas 3 ac 5 2.77 3.06 2.25
Total reducing sugar after inversion...............-02-22-22 eee eee eee ee z 5.79 14.29 20.27
Dry basis:
"T pedueing SUGAl.. cccaie geenysenan ees se eee dew eet nema tesa eens . 5.37 16.54 22. 47
SUros@isescesese-cnccexagemeeespen eeeecuntsienincantns aa aeneenintentetoneiee se 5.18 4.57 2. 82
10. 55 2111. |oosswsie see

 

 

 
r

STORING POLLEN IN THE HIVE. 29

These analyses show conclusively that a very large amount of
sugar has been added to the pollen by the time it reaches the cor-
bicule. Calculated on a dry basis just about twice as much sugar is
present in the basket pollen as in that from the corn plant. Not only
is this so, but the additional fact is disclosed that over three times as
much reducing sugar is present in the corbicular pollen as sucrose.
This latter result indicates that honey (largely a reducing sugar)
rather than nectar (containing more sucrose) is the chief sugar in-
gredient of the corbicular pollen. The additional amount of sugar
(here again a reducing sugar) in the stored pollen of the hive is
what might be expected, since it is supposed that the workers add
honey and possibly other ingredients to the pollen within the
storage cells.

The total solid percentages, corn 53.47, corbicula 66.94, stored
pollen 79.66, also show that the fluid substance which is added is one
highly charged with solids, a condition which honey amply fulfills.

In the descriptions which have been cited of the pollen-gathering
process in which the mouth is supposed to supply the requisite fluid
three substances are mentioned: Nectar, honey, and saliva. The
analyses herein given indicate that reducing sugar is mingled with
the pollen, and in the case of corn it is indicated that honey is used
in greater abundance. Without doubt a certain amount of saliva
also finds its way to the pollen, but the proportion of this substance
has not been determined. This salivary fluid may have adhesive
qualities, but this is scarcely necessary, since honey alone is amply
sufficient for this purpose.

It appears probable that the fluid which a bee adds to the pollen
which it is collecting varies somewhat in amount, since the pollen of
different plants differs considerably in moisture content and that of
the same plant will differ in this respect at different times. Pollen
collected in the early morning before the dew has left the plant is
much more moist than that found upon the same plant later in the
day, and the grains, if taken when moist, have a natural tendency to
become aggregated and form small masses. Moreover, this may ex-
plain the fact that bees make their pollen-collecting trips during the
morning hours, rather than in the afternoon, although some may be
seen upon the flowers throughout the whole day.

STORING POLLEN IN THE HIVE.

When the bee has fully loaded its baskets and before it returns to
the hive it often spends a little time upon the plant from which it
has been collecting, occupied with the task of cleaning scattered
grains of pollen from its body and of patting down securely the loads
which it has obtained. Upon its return to the hive it hurr‘es within
and seeks for a suitable place in which to deposit the pollen. Some
30 BEHAVIOR OF HONEY BEE IN POLLEN COLLECTING.

returning bees walk leisurely over the combs and loiter among their
sister workers, while others appear to be greatly agitated, shaking
their bodies and moving their wings as though highly excited.
Many pollen-bearing bees appear eager to receive food upon their
return to the hive, and they will solicit it from other workers or
take it from the honey-storage cells. The workers of the hive at
times take a little of the fresh pollen from the baskets of the laden
bee, nibbling it off with their mandibles or rasping off grains with
their tongues.

If the combs of a colony are examined, stored pollen will be found
in various parts of the hive.’ In the brood frames the greatest amount
is located above and at the sides of the brood and between this and
the stored honey. Cells scattered through the brood from which
young bees have lately emerged may also contain pollen. In the
outer frames of the hive, where brood is less likely to be found,
nearly all of the cells may be packed with pollen, or honey-storage
cells may be found interspersed with those filled with pollen. Asa
rule pollen is not stored in drone comb, although this occasionally
happens.

As the pollen-bearing bee crawls over the combs it appears to be
searching for a suitable cell in which to leave its load. It sticks
the head into cell after cell until finally one is located which meets
its requirements, although it is an open question as to why any one of
a group should be chosen rather than another. This selected cell
may already contain some pollen or it may be empty. If partly filled,
the pollen which it contains is likely to be from the same species of
plant as that which the bee carries, although different kinds of pollen
are often stored in the same cell:

In preparation for the act of unloading the bee grasps one edge '
of the cell with its forelegs and arches its abdomen so that the pos-
terior end of the abdomen rests upon the opposite side of the cell. The
body is thus held firmly and is braced by these two supports with the
head and anterior thoracic region projecting over one of the neigh-
boring cells. The hind legs are thrust down into the cell and hang
freely within it, the pollen masses being held on a level with the outer
edge of the cell, or slightly above it. The middle leg of each side
is raised and its planta is brought into contact with the upper
(proximal) end of the tibia of the same side and with the pollen mass.
The middle leg now presses downward upon the pollen mass, work-
ing in between it and the corbicular surface, so that the mass is
shoved outward and downward and falls into the cell. As the pollen
masses drop, the middle legs are raised and their claws find support
upon the edge of the cell. The hind legs now execute cleansing move-
ments to remove small bits of pollen which still cling to the corbicular
SUMMARY. 31

surfaces and hairs. After this is accomplished the bee usually leaves
the cell without paying further attention to the two pellets of pollen
although some collecting bees will stick the head into the cell, possi-
bly to assure themselves that the pollen is properly deposited. It has
been stated by some (Cheshire, for example) that the spur upon the
middle leg is used to help pry the pollen mass from the .corbicula.
This structure is in close proximity with the mass while the middle
leg is pushing downward upon it, but its small size renders difficult
an exact estimate of its value in this connection. It is certainly true
that the entire planta of the middle leg’ is thrust beneath the upper
end of the pollen mass, but the spur may be used as an entering
wedge.

Pollen masses which have been dropped by the collecting bee may
remain for some time within the cell without further treatment, but
usually another worker attends to the packing of the pollen shortly
after it has been deposited. To accomplish this the worker enters the
cell head first, seizes the pollen pellets with its mandibles, breaks
them up somewhat or flattens them out, probably mingles additional
fluid with the pollen, and tamps down the mass securely in the bot-
tom of the cell. As is shown by the analyses of corbicular pollen and
of stored pollen, certain substances are added to the pollen after the
collecting bee leaves it in the cell. Sugar is certainly added, and it is
generally supposed that secretions from some of the salivary glands
are mixed with the pollen after deposition. It appears probable that
the stored pollen or “beebread” is changed somewhat in chemical
composition through the action of the fluids which have been added
to it, either during the process of collection, at the time of packing,
or later.

SUMMARY.

Pollen may be collected by the worker bee upon its mouthparts,
upon the brushes of its legs, and upon the hairy surface of its body.
When the bee collects from small flowers, or when the supply is not
abundant, the mouthparts are chiefly instrumental in obtaining the
pollen.

The specialized leg brushes of the worker are used to assemble the
pollen, collecting it from the body parts to which it first adheres and
transporting it to the pollen baskets or corbicule of the hind legs. In
this manipulation the forelegs gather pollen trom the mouthparts and
head; the middle legs, from the forelegs and from the thorax; the
hind legs, from the middle legs and from the abdomen.

The pollen baskets are not loaded by the crossing over of one hind
leg upon the other or to any great extent by the crossing of the middle
legs over the corbicule. The middle legs deposit their loads upon the
82 BEHAVIOR OF HONEY BEE IN POLLEN COLLECTING.’

pollen combs of the hind plantz, and the plante, in turn, transfer the
pollen of one leg to the pecten comb of the other, the pecten of one
leg scraping downward over the pollen comb of the opposite leg.
(See fig. 7.) A little pollen is loaded directly from the middle legs
into the baskets when these legs are used to pat down the pollen
masses. (See fig. 6.)

Aside from the foregoing exception, all of the pollen which reaches
the baskets enters them from below, since it is first secured by the
pecten combs, and is then pushed upward by the impact of the
rising auricles, which squeeze it against the distal ends of the tibize
and force it on into the baskets to meet that which has gone before.

The long hairs which form the lateral boundaries of the baskets
are not used to comb out pollen from the brushes of any of the legs.
They serve to retain the accumulating masses within the baskets and
to support the weight of the pollen, as it projects far beyond the
surfaces of the tibia.

Pollen grains are moistened and rendered cohesive by the addition
to them of fluid substances which come from the mouth. Analyses
show that honey forms a large part of this moistening fluid, although
nectar and secretions from the salivary glands are probably present
also.

In the process of pollen manipulation this fluid substance becomes
well distributed over the brushes of all of the legs. The forelegs
acquire moisture by brushing over the mouthparts, and they transfer
this to the hairs of the breast and to the middle-leg brushes when
they come in contact with them. The middle-leg brushes transmit
their moisture to the pollen combs of the hind legs when they rub
upon them. All of these brushes also transport wet pollen which
has come from the mouthparts and thereby acquire additional mois-
ture. The auricles and the plant of the hind legs become particu-
larly wet from this source, since fluid is squeezed from the wet pollen
when it is compressed between the auricles and the distal ends of the
tibie. Dry pollen which falls upon the body hairs becomes moist
when brought into contact with the wet brushes or with wet pollen.

During the process of manipulation pollen passes backward from
its point of contact with the bee toward its resting place within the
baskets.

Pollen which the collecting bee carries to the hive is deposited by
this bee within one of the cells of the comb. As a rule, this pollen is
securely packed in the cell by some other worker, which flattens out
the rounded masses and adds more fluid to them.
BEHAVIOR OF HONEY BEE IN POLLEN COLLECTING. 33

BIBLIOGRAPHY.

ALEFELD, Dr.—Vol. 5, Nos. 15 and 16, Hichstiidt Bienen Zeitung. Summarized
in “Die Bienenzeitung in neuer, geschichteter und systematische geordneter
Ausgabe.” Herausgegeben vom Schmid und Kleine: Erste Band,
Theoretischer Theile. 1861.

CastEeEL, D. B., 1912.—The manipulation of the wax scales of the honey bee,
Circular 161, Bureau of Entomology, U. S. Dept. Agriculture, pp. 15.

CHESHIRE, F. R., 1886.—Bees and bee-keeping; scientific and practical. Vol. I,
scientific ;. II, practical. London.

FLEISCHMANN und ZANDrER, 1910.—Beitrige zur Naturgeschichte der Honigbiene.

Franz, A., 1906.—In “Unsere Bienen,” herausgegeben von Ludwig, A., Berlin.
pp. [viii] +831.

Homme tt, R., 1906.—Apiculture, Encyclopédie Agricola, Paris.

Puiuies, E. F., 1905.—Structure and development of the compound eye of the
bee. Proc. Acad. Nat. Sci. Philadelphia, vol. 57, pp. 123-157.

SLapen, F. W. L., 1911.—How pollen is collected by the social bees, and the
part played in the process by the auricle. British Bee Journal, vol. 39,
pp. 491-493, Dec. 14.

SiLaven, F. W. L., 1912.—(a@) How pollen is collected by the honey bee. Nature,
vol. 88, pp. 586, 587, Feb. 29.

1912—(b) Further notes on how the corbicula is loaded with pollen.
British Bee Journal, vol. 40, pp. 144, 145, Apr. 11.

1912.—(¢) Pollen collecting. British Bee Journal, vol. 40, pp. 164-166,
Apr. 25,

1912.—(d) How propolis is collected. Some further notes on pollen-
collecting. Gleanings in Bee Culture, vol. 40, pp. 335, 336, June 1.

1912.—(¢) Hind legs of the worker honey bee. Canadian Bee Journal,
vol. 20, p. 203. July.

Worrr, O. J. B., 1873.—Das Pollen-Einsammeln der Biene. Hichstadt Bienen-

Zeitung. 29 Jahrg. Nrs. 22 u. 23, pp. 258-270.
INDEX.

 

Page.
ALEFELD on pollen moistening by worker bee_------------------------- 23
Antenna cleaner of worker bee, figure--------_------------------------- 8
Auricle of hind planta of worker bee, definition_.__-_------------------ 9
figure 222. ese ee siess 1

role and action in pollen collect-
ANG 2 Sees Sse 16-17, 19, 20-22

Basket, pollen. (See Corbicula.) ‘

Brush of foreleg of worker bee, action and réle in pollen collecting______ 13

figure: ..323s- sub Sea eee eae

Bumblebee, moistening of pollen, views of Sladen_-----~------
.CHESHIRE on process of loading pollen baskets by worker bee__

 

 

 

TES anos cetewewaracancon=
role and action in pollen col-
lé@ting. 22522 sas se 16-19
Corbicula of worker bee, definition__ pet td bs 9
j PPULC 2. oe ee eee ete see oo 10
process of loading__---_------------~.-------- 15-22
Corn, sweet, pollen collecting therefrom by honey bee_-------------___-_ 11-13
Coxee of worker bee, figures________-_____---------------------------- 8,9
Dunpar, Dr. P. B., analyses of corn pollen from plant, from corbicul#
of beés, and. from hivé: Gell§_.—.——.=-- 22522 as ses a eee ee ee 28
Femora of worker bee, figures____-__---_-_------------+----------- 8, 9, 10, 11
FLEISCHMANN and ZANDER on process of loading pollen baskets by worker
bee. ; 18
Flowers, variable amounts of pollen from different plants____-__--_____ 10-11
Franz on pollen moistening of worker bee___------------------------_- 23
process of loading pollen baskets by worker bee_____-----~___ 17
Hairs, branched, of honey bee, use in pollen collecting_______________-__ 7-8
fringing pollen basket, function______--~ Bite ecbobeeee cusses 20
unbranched, of honey bee, use in pollen collecting________________ 7,8
HomMELL on pollen moistening of worker bee_________-_____-_--_-_______ 23
process of loading pollen baskets by worker bee_-_---------_- 1s
Honey, use by worker bee for moistening pollen________------__--_-_- 24, 28-29
Leg, hind, of worker bee, loaded with pollen, figure-_-----------------_- 22
Legs, fore, of worker bee, action and rdle in pollen collecting----_-_____ 12,13
hind, of worker bee, action and réle in pollen collecting_______ 18, 16-18
stages in basket-loading process, figure______ 19
middle, of worker bee, action and réle in pollen collecting______ 138, 14-16
of worker bee, action in unloading pollen_____-_----_--_-_--______ 30-31
structures used in pollen collecting.-______________ 7-9
36 BEHAVIOR OF HONEY BEE IN POLLEN COLLECTING.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Page.
Mandibles of honey bee, action and réle in pollen collecting_--------___ 8,13
worker bee, use in packing pollen in the cell__--_--------- e 31
Maxille of honey bee, action and réle in pollen collecting_.__.____.----.. 8,13
Moistening of pollen by bumblebee, views of Sladen____.______--------__ 23-24
honey bee. 18, 22-29
Mouthparts of honey bee, action and réle in pollen collecting_--__--_-____ 8,138
Nectar, supposed use by worker bee for moistening pollen_______--__-___ 24-29
Palma of foreleg of worker bee, definition_..____-_______.-----..----..-.-- 8
Pecten of hind tibia of worker bee, definition 9
ASULCs oo Su eee 11
réle and action in pollen collecting_. 16-19
Plauta of hind leg of worker bee, definition___-----__-_----------_-_--- 8
figures)... sc 2 es ee eee 10,11
structures concerned in pollen collect-
ing s sed 9
middle leg of worker bee, definition_._._______--__.-__--_-____-_ 8
Pollen, chemical composition Ss 26
collecting by worker bee, bibliography_---____----_____________ 32
general statement regarding it__.____ 11-13
summary of process______--_--------- 31-32
corn, from plant, from corbicule of bees, and from hive cells,
analyses to determine nature of moistening fluid-_____________ 28-29
moistening by bumblebee, views of Sladen__---___----------___- 23-24
honey bee ~--- 22-29
storage: in the hives <<... s-. cscs sso ecole suse se osoees 29-31
structures of honey bee concerned in manipulation_____________ 7-9
supply of honey bee 10-11
unloading process by worker bee 30-81
Saliva, supposed use by worker bee in moistening pollen____-_-_________ 23, 29
SLADEN, observations on process of loading pollen baskets by worker
DCG i ah eet 18, 20, 21
views as to pollen moistening by worker bee_--_____-______ 23-24, 27
Spur of middle tibia of worker bee, figure. oe 9
Storing pollei-iti the: hive.=. ==. en ee ee esse 29-31
Structures of honey bee concerned in manipulation of pollen____________ 7-9
“Sweat glands” of Wolff within hind tibia and planta of worker bee,
supposed function ewe 24
Tibia of hind leg of worker bee, modifications and structures for pollen
collecting. came 9
Tibia of worker bee, figures, 5: 8, 9, 10, 11
Tongue of worker bee, action and réle in pollen collecting____.__________ 8, 13
Trochanters of worker bee, figures. 8,9
Wax shears or pinchers, so-called, use in loading pollen by worker bee___ q
WoLFF on pollen moistening by worker bee____--_--------------------- 24

ZANDER, FLEISCHMANN and. (See Fleischmann and Zander.)

O
Issued October 4, 1912,

 

 

U. S. DEPARTMENT OF AGRICULTURE,

BUREAU OF ENTOMOLOGY—CIRCULAR No. 161.
‘LO. HOWARD, Entomologist and Chief of Bureau.

 

THE MANIPULATION OF THE WAX
SCALES OF THE HONEY BEE.

BY

D. B. CASTEEL,-Pu. D.,

Collaborator; Adjunct Professor of Zoology,
University of Texas.

 

 

WASHINGTON : GOVERNMENT PRINTING OFFICE : 1912
BUREAU OF ENTOMOLOGY.

L. O. Howarp, Entomologist and Chief of Bureau.
C. L. Mariatt, Entomologist and Acting Chief in Absence of Chief.
R. 8. Crirron, Executive Assistant.
W. F. Tastet, Chief Clerk.

F. H. CH1rrenpben, in charge of truck crop and stored product insect investiga-
tions. :

A. D. Horxins, in charge of forest insect investigations.

W. D. Hunter, in charge of southern field crop insect investigations.

¥. M. Wexstrr, in charge of cereal and forage insect investigations:

A. L. QUAINTANCE, in charge of deciduous fruit insect investigations.

KK. F. Puinuirs, in charge of bee culture. ,

D. M. Rocrers, in charge of preventing spread of moths, field work.

Roiua P. Currig, in charge of editorial work.

Mase Cotcorp, in charge of library.

INVESTIGATIONS IN BEE CULTURE.
E. F.: PHIuirs, in charge.

G. F. Wuitr, J. A. NELSON, experts.

G. S. DemutH, A. H. McCray, N. E. McInbDoo, apicultural assistants.
D. B. CASTEEL, collaborator,

PEeaRLE H. GaRRison, preparator.

Ir

 

 

ADDITIONAL COPIES of this publication
may be procured from the SUPERINTEND-
ENT OF DOCUMENTS, Government Prin

Office, Washington, D. C., at 5 cents per copy

 
CIRCULAR No. 161.
Issued October 4, 1912.

United States Department of Agriculture,

BUREAU OF ENTOMOLOGY.

L. O. HOWARD, Entomologist and Chief of Bureau.

THE MANIPULATION OF THE WAX SCALES OF THE
HONEY BEE.

By D. B. CasTEet, Ph. D.
Coliaboratar; Adjunct Professor of Zoology, University of Texas.
INTRODUCTION.

The particular form of bee activity with which this paper deals
- is that which results in the removal of the wax scales from the bodies

of the worker bees and in the application to the comb of the wax
thus obtained. A detailed presentation of the facts will be given
and attention called to certain current conceptions of this process
which are in error.

Since the bee is a very lively insect it is not surprising that the
bodily movements upon which some of its activities depend are
extremely difficult to follow and may easily be misunderstood. All
of its highly specialized legs may be used at once in the performance
of some intricate process, and the observer is in need of keenness of
sight and patience if he would gain more than an approximate
understanding’ of the parts taken by the several members. .

In the more permanent literature of apiculture and of zoology
will be found well-written accounts of the habits of bees, accounts
which are founded upon a large amount of careful observation and
which represent the work of many students of bees from the time
of Huber on. As the years have gone by, errors of sight and of
judgment have gradually been eliminated, so that at the present time
our knowledge of bee life, so far as it goes, rests upon a fairly
satisfactory foundation of authenticated facts. Yet many puzzling
questions are still unanswered, and some supposed facts may still be
doubted.

An examination of a number of bees from an active colony will

show great variation in the appearance of the wax scales of differ-
54505°—Cir. 161—12 1
2 MANIPULATION OF WAX SCALES OF THE HONEY BEE.

ent members of.the colony. In some cases no scales can be observed,
even upon dissection. In others the scales will be found to be ex-
tremely thick and completely filling the wax pockets. Some bees
will show scales in two or three pockets and none in others. Many
of the workers will possess a complete supply of scales, either all
of about the same thickness or varying considerably in thickness.
These and other diverse conditions present themselves for explana-
tion.

The present account is particularly concerned with the manipula-
tion of the wax scales. By what process or series of processes are
the scales of wax removed from their pockets and added to the
comb? That the wax which forms the comb is produced by the bees
themselves, being elaborated within their bodies and given out in the
form of thin plates or scales, is a fact well known to all students
of bees; but many differences of opinion have been expressed con-
cerning the exact method of wax manipulation. It is also well
known that the workers of the hive perform many duties—build-
ing the comb, gathering the stores of pollen and honey, caring for
the brood and the queen, repairing, cleaning, ventilating, and guard-
ing the hive—and it has been fairly well established that in some
cases, at least, these duties vary with the age of the individual
worker, although more accurate information on this point is much.
to be desired. Dreyling’s* results, in particular, indicate that bees
of certain ages are incapable of producing wax, since their glands
are either undeveloped or atrophied. Do these bees use the wax
secreted by others, taking it from them, manipulating it, and form-
ing it into comb? By careful observation bees devoid of wax scales
or with scales too thin for satisfactory removal may be discovered
working with the wax. Do these bees procure their wax from other
workers, or are they merely reworking the wax of the comb? Upon
each hind leg of a worker bee is located a peculiar pincers-like
structure long known as the wax shears. Do bees really use this
instrument in extracting the scales from the pockets, and if so, does
the owner of the scale perform this operation, or is the scale re-
moved by another worker? Or may it not be that the wax scales
drop from their pockets when they reach a suitable thickness, and
are salvaged by other workers and added to the comb? All of the
above interpretations of these processes have been advanced by
various observers. It is the object of this paper to present a true
account of the manner in which the scales of wax are transported
from their pockets to the comb and to point out some of the causes
which lead to diversity in scale number and scale form.

 

1 Dreyling, L. 1903. Ueber die wachbereitenden Organe der Honigbiene. Zoologischer
Anzeiger, Vol. 26.

Same.—1905. Die wachbereitenden Organe bei den gesellig lebenden Bienen. Zoolo-
gische Jahrbiicher, Abtheilung fiir Anatomie u. Ontogenie d. Thiere, Vol. 22.
MANIPULATION OF WAX SCALES OF THE HONEY BEE. 3
THE WAX-PRODUCING ORGANS.

The way in which the wax scales are formed, as secretion products
arising from the surfaces of the wax plates on the ventral side of
ihe abdomen of the workers, has been well described by others and
with apparent accuracy. The accounts of Dreyling embody the
results of a very considerable amount of work, and will, for the
present, at least, be taken at their full value. The work of Snod-
grass upon the anatomy of the wax plates and wax glands may be
relied upon. Only a brief statement will here be given of the struc-
ture of these organs and of the manner in which the scales are
formed.

As is well known, wax is produced by the worker bees only. The
location of the wax-secreting sur-
faces, or wax plates, may be readily
determined by an examination of the
ventral surface of a bee’s abdomen.
By stretching the abdomen somewhat
it will be seen that each of the last
four visible sternal or ventral plates
is divided into two regions: A pos-
terior projecting edge which is dis-
tinctly hairy, and a smooth anterior
half which is usually covered by the
next preceding plate. This anterior -
region is divided by a median ridge
into two distinct, irregularly oval
areas, which thus lie on either side
of the midventral line. These areas
are the wax plates, and upon them
the wax scales are formed. Each one
of the last four sternal plates bears
two wax plates, making eight in all. — Fre. 1.—Ventral abdominal plates

 

(See fig. 1.) of a worker bee dissected to show
z the position of the wax plates.
The glands which secrete the wax Original.
(Orig )

lie on the floor of the abdomen im-

mediately above and in contact with the wax plates, and their
secretion is deposited upon the external surfaces of the plates, exud-
ing through the many minute pores which perforate the plates. Upom
coming in contact with the air the fluid wax hardens, forming a cov-
ering over the entire outer surface of the plate, which gradually in-
creases in thickness with the continued addition of wax through the
pores. In this way the wax scales are produced, and since they are

 

1 Snodgrass, R. E., 1910. The Anatomy of the Honey Bee, Bur. Ent., Tech. Ser. 18,
U. 8S. Dept. Agr.
4 MANIPULATION OF WAX SCALES OF THE HONEY BEE.

molded upon the surfaces of the eight wax plates they correspond to
them in number and in form.

In its natural position each wax scale lies between its wax plate
and the overlapping edge of the next preceding sternal plate. The
scale thus fits into a little crevice or wax pocket and is well protected
from injury. If the bee extends its abdomen the rear edges of the
scales can be seen protruding from their pockets, or if the scales be-
come very thick they will push the covering sternal plates outward
and will project from the pockets.

THE FORMATION OF THE WAX SCALES.

The problem of wax secretion has been extensively studied by
Dreyling, who shows that the wax glands differ markedly in struc-
ture in bees of different ages. In the newly emerged bee the epider-
mis which underlies the wax plate is composed of epithelial cells
nearly cubical in form. As the bee grows older these cells become
elongated and are separated by clear spaces, and when the bee has
reached the height of its activity as a wax producer these gland cells
are elongated and show liquid wax stored in the spaces between them.
When the wax-secreting period is over these cells degenerate, so that
in sections through the glands of old field bees, or of bees that have
lived over winter, the layer of cells beneath the wax plates appears
greatly shrunken, and individual cells can be distinguished by their
nuclei only.- These histological data are given by Dreyling in sup-
port of the conclusion that the secretion of wax in much more abun-
dant at a certain period in the bee’s life and that old bees and-very
young bees are, as a rule, incapable of wax production. These con-
clusions are in harmony with the practical experiences of bee keepers.

METHODS OF OBSERVATION.

In a study of the behavior during scale removal and wax building
it is necessary to watch the bees -while they are working naturally
within the hive. To accomplish this, observatory hives are used in
which glass is substituted for wood in part of the construction.
Most of the work is done upon colonies in modified nucleus boxes
(fig. 2). The two sides are removed from each hive and are replaced
with glass in the form of sliding doors, two to a side, and glass plates
are fitted to the top. It all cases wooden shades cover both sides and
top when the bees are not under observation. Although bees are
somewhat disturbed when light is first admitted to the hive, they ap-
pear to become accustomed to it and work normally unless the hive is
left open for too long a period.

When a hive is well crowded with bees, and when the frames are
widely spaced, the workers are apt to extend the comb above the levél
of the top bars of the frames until it comes in contact with the glass.
This gives the observer an excellent opportunity to study the comb
MANIPULATION OF WAX SCALES OF THE HONEY BEE. 5

workers at close range, and it also obviates the necessity of placing
glass ends in the hive against which comb might be built.

Even with the best of arrangements it is difficult to follow some of
the movements of the workers during the act of scale removal. As
an aid to vision a Zeiss binocular microscope is used, the tubes being
removed from the stand and held to the eye after the manner of a
field glass. By the use of this instrument a bee appears to acquire

 

 

 

 

 

 

 

 

Fie. 2.—Observatory hive. The sides are fitted with sliding glass doors, and two pieces of
glass cover the top. The sliding glass doors allow the observer to gain access to any

. small area of the outer comb without removing the glass from the entire side of the
hive. Screens of wood cover the glass of the sides and top when the bees are not under
observation. (Original.)

the dimensions of a large-sized rat, and the action of its legs and
mandibles may be followed with great precision.

For the sake of later identification many cf the bees are marked
by painting different colors on their backs, and some are numbered.
Such distinctive marks make it possible to follow the actions of an
individual bee from day to day.

The observations here recorded were made during the summer of
1911 at the apiary of the Bureau of Entomology.
6 MANIPULATION OF WAX SCALES OF THE HONEY BEE.

REMOVAL OF THE WAX SCALES.

The determination of the exact method by which the wax scales
are removed either comes as the result of prolonged and patient

 

Fic. 3.—Ventral view of a worker bee in the act of
‘ removing a wax scale. The two middle legs and
the right hind leg are used for support, while the
left hind leg removes the scale.

watching or is the product
of good fortune. Long be-
fore the observer is able to
decide upon all of the de-
tails of the process he
becomes convinced that
usually the scales are re-
moved by the bee which
secretes them and by this
bee are masticated and
added to the comb. The
workers never assist each
other in the process of re-
moval, although, as _ will
be mentioned later, free
scales may, in some cases,
be handled by other
workers.

As a rule, the scales are
removed while the bee is

standing on the comb or its support, and the wax thus obtained is
applied to the comb near the place where it is removed. Since the
whole process of removal takes place beneath the workevr’s body it

can be observed most
satisfactorily when
the bee is seen from
the side or when it is
building comb against
a glass plate.

The posture of a
bee in the act of re-
moving a scale is
rather characteristic
and is at once recog-
nized by one familiar
with it. Immediately
before the scaleistobe
removed the bee may

 

Fig, 4.—Side view of a worker in the same posture as
that shown in figure 3. (Original.)

be busily engaged upon the surface of the comb, plying with its man-
dibles the wax of the scale last extracted or reshaping and polishing
wax already deposited, its whole body somewhat agitated, moving
MANIPULATION OF WAX SCALES OF THE HONEY BEE. q

backward and forward or from side to side as it adapts its position to
the work in hand. Suddenly its body becomes very quiet. The fore-
legs and mandibles are raised from the comb, and the head is held
with the face inclined tow-

ard the comb. The hind - auuibll
leg of one sidé is now :
raised, and its flattened
first tarsal segment or
planta is slipped alpng the
ventral surface of the ex-
tended abdomen and comes
in contact with the pro-
truding wax scales of the
corresponding side (figs.
3 and 4). The weight of
the bee is now supported .
upon three legs; upon the
middle leg of the side
from which the scale is to
be removed and upon the

iy

   

= < Fig. 5.—Ventral view of a worker bee showing the
middle and hind legs of position of the wax scale just before it is grasped

the ‘other side. The first by the forelegs and mandibles. .The scale is still
adhering to the spines of the pollen combs. The
tarsal segment of the leg bee is supported upon the two middle legs and

which is to’ remove the upon the hind leg which is not removing the scale,
x (Original. )

scale is now pressed firmly

against the abdomen, and the edge of a protruding scale becomes
engaged with it. Steady, continuous pressure is now exerted both
against the abdomen and toward the rear, with the result that the
scale is drawn out of its
pocket but remains at-
tached to the leg which
removed it. The hind
leg bearing the scale is
now, quickly flexed tow-
ard the thorax and
head, thus carrying the
scale forward under the
body of the bee and
placing it in a position

 

Fig. 6.—Side view of a worker bee in the same posture ° =
as that shown in figure 5. Original.) where it may be readily

grasped by the forelegs
or the mandibles (figs. 5 and 6). Sometimes the scale is appar-
ently removed from the hind leg by the mandibles alone, but usually
the forelegs aid in this process and also manipulate the scale while
8 MANIPULATION OF WAX SCALES OF THE HONEY BEE.

the mandibles are masticating it. After the scale has been thor-
oughly masticated the wax is applied to the comb.

THE SCALE-REMOVING ORGAN.

A point of particular interest in the process of wax scale removal
is that which deals with the manner in which the scale is grasped by

 

Fic. 7.—Inner surfabe of the left
hind leg of a worker bee, show-
ing the position of a wax scale
immediately after it has heen re-
moved from the wax pocket. The
scale has been pierced by seven
of the spines of the pollen combs
of the first tarsal segment or
planta. The jaws of the so-
ealled wax shears or pincers are
formed by the pecten spines
above and the surface of the
auricle below. (Original.)

the hind leg which removes it. As is
well known, each hind leg of the worker
bee bears a pincerslike structure—the
so-called wax shears—located at the
juncture of the tibia and the flattened
first tarsal segment or planta (fig. 7).
According to the statements of numer-
ous writers, the wax scales are grasped
between the edges of the supposed
pincers formed by the pecten above and
the auricle below, and are either snipped
off or are held by the jaws of the
pincers and thus drawn from the pock-
ets. Cowan’s' account may be given
as typical of others which are current
in the literature of apiculture and of
zoology.

The articulation of the tibia and planta
being at the anterior angle, and the absence
of the spur on the tibia (which only the
honey bee does not possess) give the pecten a
freedom of action it would not otherwise have
and enable it to be used together with the
auricle on the planta, which is quite smooth,
as a true pair of pincers, and as an instru-
ment for laying hold of the thin flakes of
wax, and for bringing them forward to be
transferred by the other legs to the jaws for
manipulation.

As a matter of fact, the wax shears
have nothing whatever to do with the
removal of the wax scales. They per-
form an entirely different function, be-
ing concerned with the gathering of
pollen in a manner to be described in a
future paper.

_ In coming to the above conclusions the writer was first convinced
that the so-called wax shears are not-used in removing scales by.
toting that the position of the tibio-tarsal joint at the time of scale

 

1 Cowan, T. W., ‘‘ The Honey Bee,” 2d ed., London, 1904.
MANIPULATION OF WAX SCALES OF THE HONEY BEE. 9

removal is such as to make it impossible’ for the pincerslike crevice
to grasp the scale. Moreover, the open jaws of the shears point lat-
terally and away from the scales rather than toward them, nor,
indeed, is it possible for the shears to grasp even the projecting edges
of any of the ventral or lateral body plates and thus steady or guide
the leg as it seeks contact with the scales.

The transverse rows of spines upon the planta, called pollen combs,
and not the wax shears are instrumental in the removal of scales.
Snodgrass (1910), in discussing the anatomy of the hind leg and
its functions, states that the wax is “poked out of” the “ pockets
by means of the spines on the feet ’—“ with the ordinary hairs or
spines of the tibie or tarsi,” and the same general conclusions were
reached independently by the writer, but with this exception ; only
the spines of the first tarsal segment (planta) function in this
manner, and usually only certain large spines in the rows at the dis-
tal end of this segment.

It is exceedingly difficult to capture a bee at the very moment at
which the scale is being drawn from its pocket and before it has been
carried to the mouth, and even if this is accomplished the captive is
very likely to drop the scale from the hind leg in its struggles to
escape. If, however, one is successful, the scale-removing leg will
show the little wax scale adhering to the distal end of the inner
surface of the first tarsal segment, being pierced in several places
by the strong spines which project from the lower rows of the pollen
combs. (See fig. 7.).

It can also be shown experimentally that this method of remov-
ing the wax scales is entirely possible, for if the hind tarsus of a bee
is mounted upon a small stick and is gently rubbed along the ventral
side of a fully extended dead bee’s abdomen, holding it in such a.
position that the pollen combs brush over the projecting edges of the
scales, one of the scales will probably be removed and will be seen
adhering to the spines in the manner above described.

In any hive where comb is being constructed rapidly many free
scales will be found upon the bottom board and upon the lower bars
of the frames. If these scales are examined microscopically some
will be found without marks upon them, having. evidently been
loosened from their pockets accidentally during the movements of
the workers over the comb and around the hive. Others will show
certain marks and scratches upon them, indicating that they were
voluntarily removed from the pockets, and in some cases they may
bear the marks of the mandibles, showing that they were dropped
during the process of mastication. Most of the scales which are
marked at all are indented with several small punctures showing the
places where the spines of the pollen combs have pierced cit,
These scars are exactly similar in appearance to those on the scale
10 MANIPULATION OF WAX SCALES OF THE HONEY BEE.

shown in figure 7. Such free scales are not marked as they would be
had they been extracted by such a structure as the so-called wax
shears.

So far as can be determined there does not appear to be any regu-
lar order for the removal of scales. One may be taken from the
left side and then one from the right, or the bee may remove two or
three from one side in succession. An attempt to remove a scale is
by no means always successful, the worker often trying first one side
and then the other, pressing the pollen combs against the more ante-
rior scales and running them down to the most posterior, until at
last a scale is impaled upon the spines or the bee discontinues its
efforts.

FURTHER MANIPULATION AND THE MASTICATION OF SCALES.

‘When a scale has become attached to the spines it is transferred to
the mouth with great rapidity, so swiftly, in fact, that the eye can
scarcely follow the action. This is not surprising, for it is necessary
only to flex the leg toward the head to bring the scale in close con-
tact with the forelegs and mandibles. The leg is rotated through
the arc of a circle, downward, forward, and upward, while at the
same time the head is slightly turned under to receive the scale.
The process of mastication is more prolonged. It is usually sup-
posed that the pure wax of the scale differs in chemical composition
from the wax of the comb, this change being accomplished during
mastication, by which process the wax is mixed with saliva, becomes
translucent rather than transparent, changes somewhat in color, and
becomes more pliable.

The behavior of a bee upon receiving a wax scale at its mouth is
subject to considerable variation. On some occasions the scales are
apparently manipulated by the mandibles alone, while at other times
the forelegs are brought into requisition and assist the mandibles.
When a scale is thin and small and has been firmly grasped by the
mandibles little assistance is needed from the legs. But if a
scale of medium or extra thickness is presented, or if the mandibles
do not hold it securely and it is in danger of falling from the mouth,
the two forelegs are used to great advantage in readjusting the scale
and in so holding it that the mandibles may be applied to it most
advantageously. Ifa scale is small and thin, it may be masticated
entirely before any wax is applied to the comb; but if of considerable
size a portion only may be prepared, this deposited upon the comb,
and then the remainder treated in a similar manner.

As a rule the wax which is deposited upon.the comb by the pro-
ducing bee is first subjected to the action of the mandibles and
mixed with saliva. Such, however, is not always the case, for some
bees appear to be “careless” and will mingle small unchewed por-
tions ef scales with the masticated wax. Indeed, it is not uncom-
MANIPULATION OF WAX SCALES OF THE HONEY BEE. 11

mon to find nearly perfect scales mixed with the wax of a newly
made comb. The masticated wax itself is spongy and flaky when
it is deposited by the producing bee and will later be reworked,
thereby gaining greatly in compactness and smoothness.

The entire process of the removal of one scale, its mastication, and
the application of the wax to the comb is completed in about four
minutes, only a very small portion of this interval being consumed in
the work of extracting the scale from its pocket and passing it to the
mouth, except,.in cases in which scales appear to be removed with
difficulty.

FREE SCALES.

When wax scales are voluntarily removed they are taken off by
the bee which secretes them and in the manner above described.
Many, however, are accidentally detached, being loosened from their
pockets by movements of the abdomen, incidental cleansing move-
ments of the legs, or by contact with objects both within and without
the hive. Such scales, and also those which are dropped in the
course of transference from the wax pocket to the mouth, may or
may not be recovered later and added to the comb. Since old wax
is used over and over again in the rebuilding of comb, it is but
natural to expect that scattered scales would likewise be utilized by
the colony and not be allowed to go to waste, and it is probably true
that such is usually the case. Yet there appears to be no concerted
action among the workers to salvage such particles of wax, no class
of comb workers whose duty it is to pick such material from the
bottom board of the hive and carry it to the comb. Scales which
drop are likely to remain for a long time, and some may even be
carried out through the entrance with waste material. If, however,
scales accidentally dislodged or voluntarily removed fall on the
comb among the comb workers they are often noticed by them, picked
up, masticated, and built into the comb. If a scale slips from the
pollen combs or is fumbled by the bee before being grasped by the
mandibles, it is seldom recovered by the worker to which it belongs
unless it. falls very near her or she stumbles upon it accidentally.

PARTIAL REMOVAL OF SCALES,

Although a bee endeavors to remove an entire wax scale at one
operation, the attempt is not always successful. A scale that has
become very thick is difficult of removal, particularly so if the outer
edge is broken or beveled. When the bee applies its pollen combs to
such a scale the spines may fail to get a hold upon the wax, or they
may not become sufficiently well fixed in it to make possible the re-
moval of the entire scale. Instead of this, shreds and small pieces of
wax are torn off and remain sticking to the bristles of the pollen
12 MANIPULATION OF WAX SCALES OF THE HONEY BEE.

combs. These may be entirely disregarded by the bee, or they may
_ be cleaned off by scraping the combs together, the shreds of. wax
dropping to the bottom of the hive. More usually, however, if a
worker is actively engaged in the task of adding to the comb these
bits of wax will be carried forward to the mouth, masticated, and
applied.

In one case which came under observation a worker had removed
all of its wax scales except a very large, thick one which was evi-
dently sticking tightly in its pocket. Repeated efforts were made by
the bee to accomplish the extraction of this scale, but with only
partial success, since the main portion of the scale remained in the
pocket. But. as the result of its efforts the bee succeeded in beveling
off the entire projecting edge of the scale, rasping it off bit by bit
and carrying the small pieces forward to the mouth, masticating
them, and dispositing the wax upon the comb.

PRODUCERS AND BUILDERS.

The presence of well-developed scales protruding from the pockets
of a worker does not necessarily indicate that this individual will
shortly add this wax to the comb, even though the colony may at the
time be producing comb at a rapid rate. Such a bee may be working
upon the comb as a molder of wax rather than as a producer. One
who is intent upon a study of the process of scale removal will often
be disappointed after following for a time the movements of a
worker ‘that is evidently manipulating wax and which shows the
protruding edges of scales beneath its abdomen, for the wax with
which it is working is being picked up, little by little, from the comb
and comes not from its own body. This reworking of wax is one of
the most characteristic features of comb construction, for it goes on
continually while new comb is being produced, and it. is, of course, a
necessary process in the reconstruction of old comb.

The claim has been made by several investigators and writers that
the bees which sculpture the wax are not at the same time concerned
with its secretion and deposition—that there are producing bees
and building bees. In a sense this is true, but not entirely so. With-
out doubt many active comb workers are, at the time, nonproductive,
for the wax glands of many are not functionally active. The re-
sults of Dreyling would indicate that the old bees, at least, might be
considered as falling in this class, and the direct abeenvatians of the
writer lead to the conclusion that, old bees devoid of wax scales per-
form a considerable share of the labor of reworking newly deposited
wax and of shaping and polishing the cells of the comb.

However, as noted above, bees with well-developed wax scales
often busy themselves with wax working rather than with produc-
tion. Moreover, a bee that is removing its scales may discontinue
MANIPULATION OF WAX SCALES OF THE HONEY BEE. 13

this work and give its attention to the molding of wax laid down
by others. This may occur immediately after a worker has removed
the last of its scales, or the bee may turn to sculpturing while several
scales yet remain in the pockets. It is thus evident that the produc-
ing bee may also be a worker of wax produced by others and that
nonproductive bees do not monopolize the work of sculpturing and
polishing the comb.

SUMMARY.

As is well known, the wax produced by the worker bee occurs in
the form of scales, eight in number, which appear upon the surfaces
of the eight wax plates. These wax plates are located upon the
last four visible ventral plates of a worker bee’s abdomen. The wax
is secreted by glands which lie upon the inner surface of each wax
plate. ‘The liquid wax exudes through pores which perfcrate the
wax plates, and it hardens to form the scales as it comes in contact
with the air.

Unless accidentally dislodged the wax scales are always removed
and manipulated by the bee which secretes them.

In the process of removal the scale is not grasped by the so-called
wax shears, but it is pierced by a few of the stiff spines cn the distal
end of the first tarsal segment of the hind leg and is then drawn
from its pocket and remains adhering to these spines until removed
for mastication.

By flexing the hind leg the scale is brought forward beneath the
bee’s body and into proximity with the mouth. In the process of
mastication the forelegs usually aid the mandibles by holding the
scale in an advantageous position. :

No definite sequence is observed by the bee in the order in which
it removes its scales.

As a rule entire scales are removed at one operation, although it
sometimes happens that a thin scale is broken in extracting it from
its pocket or an extremely thick one is gradually beveled off by the
continued rasping of the pollen combs.

Seales which are removed accidentally or which are dropped
during manipulation may be recovered later and built into the comb,
but the recovery of free scales is usually not accomplished by the
bee which secreted them.

Bees which are producing wax may also rework the masticated
wax laid down by others. Producing bees may turn to the work of
building and sculpturing the comb either before all their scales
are removed or immediately after this has been accomplished.

O