x Cornell University Library Sthaca, New York BOUGHT WITH THE INCOME OF THE SAGE ENDOWMENT FUND THE GIFT OF HENRY W. SAGE 1891 “. NATURE SKETCHES IN TEMPERATE AMERICA hemes “Stranger, if thou hast learned a truth which needs no school of long experi- ence, that the world is full of guilt and misery, and hast seen enough of all its sorrows, crimes, and cares, to tire thee of it, enter this wild wood and view the haunts of nature.” Bryant. From “Entrance to a Wood.” Tue Troitus Burrerriy (Papilio troilus) Visiting the cardinal flower (Lobelia cardinatis) From a photograph NATURE SKETCHES IN TEMPERATE AMERICA A SERIES OF SKETCHES AND A POPULAR ACCOUNT OF INSECTS, BIRDS, AND PLANTS, TREATED FROM SOME ASPECTS OF THEIR EVOLUTION AND ECOLOGICAL RELATIONS BY JOSEPH LANE HANCOCK M.D., F.E.S. WITH TWO HUNDRED AND FIFTEEN ORIGINAL ILLUSTRATIONS IN THE TEXT, AND TWELVE COLORED PLATES BY THE AUTHOR CHICAGO A. C. McCLURG & CO. OME JS } Vg iy, AVTTS ’) CopyRIGHT Sy A. C. McCuure & Co. 1911 Published, May, 1911 Entered at Stationers’ Hall, London, England THE » PLIMPTON + PRESS [w-p-o] NORWOOD - MASS +>U*SeA TO LOUISE LAMBERT HANCOCK WHOSE UNTIRING INTEREST AND EBNCOURAGEMENT WAS ONE OF THE GREATEST INCENTIVES IN ITS PREPARATION THIS VOLUME IS GRATEFULLY DEDICATED PREFACE N a popular exposition of the facts gleaned from nature, such as the present work is intended to convey, it may be more agreeable to present the subject sometimes from the artistic or esthetic point of view. This method does not sacrifice truth, which is the religion of science, but mitigates it, bring- ing about a wider reading circle and thereby serving a greater usefulness. This work consists essentially of suggestive essays drawn from observations afield, and treating of various insects, birds, and plants. In this account there is brought together a series of life histories of many of the animal forms. I have given more consideration here to the insects than to other groups of animals. I think this is justifiable when it is remembered how many more representatives of these animals populate the earth, as compared with other families of animals. The habits of some of the commoner species of Orthoptera, or grasshoppers and locusts, have been treated at length in the text. This feature, given in the last section of the book, along with the many photographic illustrations and drawings accenting their ecological relations, it is hoped, will interest the general reader in this group. As above intimated, the relation of animals and plants to their natural surroundings has been kept constantly in mind throughout its preparation. I have treated the subject of . protective resemblance and mimicry, as well as the various protective devices inherent in insects, in a series of chapters because of the unusual interest centred in this theme. Many photographs are given, gathered with great care, of the actual live insects found in nature illustrative of pro- tective resemblance and mimicry, and I have treated many of the examples given by Darwin in his “Origin of Species,” but from the standpoint of my own views. It will be remem- bered that we have in the temperate. region but a mere straggling of animal and plant forms compared to that found vil viii PREFACE in the tropics. Yet the forms in this latitude tell us the same story of evolution as those of the hotter portions of the earth. I realize that I may color the facts at times with human imagination, but where there is danger of this I have always endeavored to support my contentions or optical proof with either photographic illustrations, or drawings from life, of what I saw. I am satisfied to let the reader draw his own conclusions. The work has been divided into sections mainly through an endeavor to show the philosophy of evolution. First, I have brought forward sketches showing special adaptations and animal behavior. Secondly, by walks afield I have attempted in a simple manner to show the application of evolution to the objects viewed. In the table of contents will be found other subdivisions of the subject. When not other- wise stated, these word sketches have been drawn from my diary notes covering many years, made at Lakeside, Berrien County, Michigan. It affords me great pleasure in this connection to acknowl- edge the generous assistance received in the correction of the manuscript to Professor Lillian V. Lambert, of the Iowa State Teachers College. My special obligation is also due Professor William L. Tower, of the University of Chicago, for useful sug- gestions while reading the manuscript, and to Dr. James W. Walker for carefully making typographical corrections in the page proofs. J. L. H. CuHIcaco, January, 1911, I. EVOLUTION AND NATURAL SELECTION INTRODUCTION SPECIES AND THEIR DESCENT — LAMARCK’S DOCTRINE REGARDING SPECIES — FUNCTIONALLY PRODUCED MODIFICATIONS — DARWIN’S PROGRESSIVE EVOLUTION THROUGH NATURAL LAW — SPECIES, VARIETIES, AND MU- TANTS DESCRIBED— NUMERICAL RELATION OF ANIMAL GROUPS — STRUGGLE FOR EXISTENCE — INCREASE IN ORGANIC BEINGS — BENE-— FICIAL VARIATIONS ARISING FROM COMPLEX AND CHANGING RELATIONS OF LIFE— NATURAL SELECTION OR THE SURVIVAL OF THE FITTEST DOES NOT IMPLY CONSCIOUS CHOICE — ANALOGY TO ARTIFICIAL SELECTION — INHERITANCE — EVOLUTION AND INSTINCT — PERFECTED INSTINCT IN ANIMALS — FORMATION OF NEW SPECIES —-MUTATION THEORY OF DEVRIES — WHITMAN’S ANALYSIS OF DEVRIES’ THEORY — PERSONAL, HISTONAL, AND GERMINAL SELECTION AS DESCRIBED BY WEISMANN — QUETELET’S LAW, TRIAL BY ERROR — ORTHOGENESIS — VARIATION — UTILITY THE BASIS OF NATURAL SELECTION — PROTECTIVE RESEMBLANCE AND MIMICRY — SEXUAL SELECTION — SUMMARY OF NATURAL SELEC— TION 2 2 6 8 @ 6 8 8 ee II. ADAPTATIONS IN ANIMALS AND PLANTS, WITH. EXAMPLES ADAPTATION — PLANT ADAPTATIONS —— FLOWER AND INSECT ADAPTATIONS —— WHY THE NECTAR GATHERERS ASSEMBLE ON THE BASSWOOD BLOSSOMS —— HOW THE MILKWEED PROFITS BY THE VISITS OF ITS INSECT GUESTS — THE SELECTED GUESTS OF THE BUTTERFLY WEED — BIRD FLOWERS — THE LITTLE PEAR-SHAPED HOUSE ON THE WITCH-HAZEL BOUGH — THE GUESTS OF THE WILD BERGAMOT-— THE SEASONAL PROCESSION OF THE FLOWERS, INSECTS, AND BIRDS—- WHAT THE POLYPHEMUS PAGES 1-24 MOTH AND CATERPILLAR SUGGEST . . - « «© © «© «© «© «© «© « 25-64 1x x CONTENTS Il]. PROTECTIVE RESEMBLANCE, WITH EXAMPLES DARWIN’S THEORY OF PROTECTIVE RESEMBLANCE — THE COLORS OF ANI- MALS ANALYZED — ACTION OF NATURAL SELECTION IN PRESERVATION OF COLORS — THE TREE-TOAD — THE HABITS OF THE WALKING-STICK — AN ILLUSIVE BUTTERFLY AND ITS FLOWER PROTECTOR — THE ANIMATED ROLLED LEAF — THE TWIG IMPERSONATOR — HOW THE ACONTIA AND STENOMA MOTHS ARE PROTECTED — PROTECTIVE RESEMBLANCE TO BARK IN CATOCALA LARVA—THE WEEVIL BARK IMITATOR— THE ARBO- REAL KATYDID — THE INVISIBLE OR THREAD-LEGGED BUG — QUAINT VISITORS TO THE SAP FOUNTAINS ON THE OAK — THE PROTECTED SCHIZURA PAGES CATERPILLAR . . 1. eee ee eee 65-114 IV. MIMICRY, WITH EXAMPLES BATES THEORY OF MIMICRY — GADOW’S CHEMICAL THEORY OF ANIMAL COLORATION — MULLERIAN MIMICRY —— THE MONARCH BUTTERFLY AND ITs MIMIC —— THE BUMBLEBEE’S MIMIC — FLOWER-FREQUENTING PUUS 6 we Kae a ee eee Re ew Re He De & Bw =m » TO V. WARNING COLORS, TERRIFYING MARKINGS, AND OTHER PROTECTIVE DEVICES, WITH EXAMPLES WALLACE’S THEORY OF WARNING COLORS — ACTION OF BIRDS TOWARDS CATERPILLARS, TESTING THEIR EDIBLENESS — SIGNIFICANCE OF COLOR- ING IN BUTTERFLIES AND MOTHS — THE PAINTED LADY BUTTERFLY AND ITS WORLD-WIDE DISTRIBUTION — THE SADDLE-BACK LARVA — THE SWALLOW-TAIL BUTTERFLIES AND THEIR CURIOUS LARVZ — THE DIs- GUISES OF THE CRESPHONTES CATERPILLAR — THE CURIOUS PUSS- MOTH CATERPILLAR — THE ACHEMON SPHINX AND ITS TAILED LARVA — 18 IT PROTECTIVE RESEMBLANCE AND MIMICRY COMBINED IN AUTO- MERIS (0P 2. ee ee ee te ee ew eee) «185-164 VI. ANIMAL BEHAVIOR, WITH EXAMPLES BOHN’S CONCEPTION OF ANIMAL BEHAVIOR — THE DISPOSITION OF THE SPECIAL SENSE ORGANS IN INSECTS-—— THE ASSASSINS IN LACE-LIKE FLOWERS OF WILD CARROT— THE TENANTS OF AN ACORN — THE “WOOLLY BEAR” CATERPILLAR’S FATE— THE ANT-LION— THE EVEN- ING PRIMROSE SPIDER TRAP— THE CASTLE-BUILDING SPIDER — THE BEHAVIOR OF A JUMPING SPIDER — THE GOLDEN SPHEX AS THE GRASS- HOPPER’S ENEMY — THE HABITS OF THE GREEN MEADOW GRASSHOPPER — THE JUG-MAKING WASP — THE HABITS OF THE WHITE-FOOTED MUD- DAUBER AND ITS ALLIES—— THE TABANID FLY AS AN AERIAL PERFORMER — THE HUNTED CICADA — THE ROSE-CHAFER — AN AUGUST HAILSTORM, WITH ITS SEQUENCE — THE MARYLAND YELLOW-THROAT —THE MORN- ING TROUBADOR OR GOLDFINCH — BIRDS AND BLUE RACERS — THE CONTENTS PHG@BE’S BIOGRAPHY — THE DEATH OF THE YELLOW WARBLER — THE RED SQUIRREL’S FROLICS — SOME VISITORS TO THE WALNUT TREE — BIRDTIME REFLECTIONS — THE BIRD OF TWILIGHT.OR NIGHT HAWK —A TRAGEDY IN THE DUNES — STRANGE MISHAPS TO BIRDS—THE TOAD’S SOCIAL LIFE—THE BIRD THERMOMETER OR INDIGO BIRD— THE CHE- PAGES WINK —TAKING SPIZELLA’S PORTRAIT . . . . . . . . 165-267 VII. GENERAL OBSERVATIONS AND SKETCHES AFIELD, WITH EXAMPLES WALKS AFIELD AS AN AID TO INTERPRETATION OF NATURE — RESULTS OF OBSERVATION —- THE FORMULATION OF PROBLEMS — SEASONAL DI- MORPHISM —— CASES OF ORIGIN BY ADAPTATION IN NATURE — VARIANTS — MUTANTS — ECADS —- MEADOW ECHOES — THE POND — THE BROOK INHABITANTS — NATURE'S LABORATORY — ANIMAL LIFE IN RAINY WEATHER — PASTURE AND MEADOW INSECTS— THE UNDER-LEAF INHABITANTS —_- THE SAND DUNES — NIGHT INSECT VISITORS TO OUR. DOORWAY — THE ‘BUMBLEBEES’ NIGHT CAMP—THE BIRDS AND SQUIRRELS’ ASSEMBLAGE GROUND — THE HERMIT THRUSH AS A SELEC- TIVE FACTOR . 6 «& «© s % &% 2 » © 4 © © & «» » 269-814 VIII. ECOLOGY — INTERPRETATION - OF ENVIRON MENT AS EXEMPLIFIED IN THE ORTHOPTERA SOURCES OF LIFE AFTER GLACIATION — HABITATS OF PLANTS AND ANIMALS — BASE LEVELLING AND SUCCESSIONS OF PLANTS AND ANIMALS —z00- GEOGRAPHY — NATURE'S RECLAMATION OF STERILE GROUND — THE HABITAT OF THE ORTHOPTERA — THE TEXAN KATYDID —— THE HOME OF THE FORKED-TAIL KATYDID AND ITS ALLIES — THE SWORDBEARER — THE CAROLINA LOCUST —— THE SPRINKLED LOCUST — THE VARIED-WING LOCUST — BLATCHLEY’S LOCUST — THE TWO-STRIPED LOCUST AND ITS RELATED SPECIES —- THE LONG-HORNED LOCUST— THE MOTTLED SAND LOCUST — BOLL’S LOCUST — THE CLEAR-WING LOCUST ——- THE LEATHER-COLORED LOCUST — THE SHORT-WING BROWN LOCUST — THE CLOUDED LOCUST — THE DRINK OF THE GRASSHOPPERS ——- THE MOLE CRICKET — THE HABITS OF THE STRIPED MEADOW CRICKETS——SOME HABITS OF FIELD CRICKETS — KATYDIDS IN THEIR NIGHT RESORTS —— THE SHORT-WINGED GREEN LOCUST — THE QUAKER LOCUST — THE PASTURE LOCUST — THE SHORT-HORNED LOCUST — THE GREEN-LEGGED LOCUST — THE GREEN- STRIPED LOCUST — THE GROUSE LOCUSTS — THE LESSER LOCUST — THE PENNSYLVANIA COCKROACH — CLASSIFIED HABITATS OF VARIOUS SPECIES OF ORTHOPTERA BASED ON THEIR EGG-LAYING SITES, SHOWING THEIR RELATION TO PLANT FORMATIONS IN GENERAL — DEFINITIONS OF COM- MON ENVIRONMENTAL COMPLEXES AND VARIOUS HABITATS OF PLANTS GROUPED UNDER FORMATIONS <8 = oe ee & «© & 9 BBS INDEX Se we we om Om en om Oa 435 LIST OF ILLUSTRATIONS PAGE Moth Mullein, Pasture Thistle, and Bumble Bee (Bombus mor- risonit), showing plant and in- sect association in July . . . i Troilus Butterfly (Papilio troilus) visiting the Cardinal Flower (Lobelia cardinalis). Colored plate. . . . . . . . Frontispiece Robber-fly (Diasyllie sacrata) . . iv Head of Pileated Woodpecker, or Logeock . 2... ix Harebell Flowers ait Bumble Bue xiii Diagram showing chief relations of animal kingdom, after Gallo- way... 4 The large aneasilis “Tebneutwen Fly (Thalessa lunator) . . . . 12 Female Arboreal Katydid ((yrto- PAGE phyllus perspreillatus). Colored plate. x Pair of Slender Conk: hesid Gis. hoppers (Conocephalus attenu- atus [ensiger]). Colored plate . Plant and Insect Association of the Meadow in September: Blazing Star (Lacinaria spi- cata) with insect visitors, the butterfly (Argynnis bellona) and the clear-wing moth (Hemaris axillaris). Colored plate . Basswood Flowers. Initial draw- LU ae ee eee a ee Insect Visitors to the Basswood Blossoms (Tibia americana) Flowers of Milkweed. Initial drawing . Nore. — Unless otherwise stated the illustrations were made at Lahetle Michigan. xiii 20 22 28 33 35 36 PAGE “Insect Visitors to the Milkweed (Aselepias cornuti). The in- sects are the red-spotted bee- tles (Tetraopes _ tetraophthal- mus). Colored plate Swamp Milkweed inearnata) .... 2... The Butterfly Milkweed, Golden- rod, and Insect Guests. Inztral drawing 2... 1 we, Ruby-throated Hiiceniag tied Initial drawing . Bill, Head, and Feathers of Rube throated Humming-bird, show- ing how pollen of plants is Carried, 3 2 4 aoa 4 4 es ‘Male Ruby-throated Humming- bird (Trochilus colubris) Spiny Galls on Witch-hazel, and Plant Lice. Initial drawing . Spiny Gall on Witch-hazel, show- ing the gall-producing aphid (Hamamelistes spinosus) in the act of leaving the gall. . . Wild Bergamot (Monarda fistu- losa) and its little yellow but- terfly visitor, Terrias lisa . Troilus Butterfly visiting the Cardinal Flower (Lobelia car- (Aselepias Moth (Telea polyphemus). . . - Polyphemus Caterpillar on bass- wood in contracted attitude. . Protective resemblance in the Snout Butterfly (Libythea back- MONTY 6. ss ho ge cA on he dR Ok Tree Toad (Hyla versicolor). . . Male Walking-stick (Diaphero- mera femorata)....... Leaves of Red Oak, showing Walking-stick protected by its resemblance to veins of the leaf, and Round-wing Katydid, almost invisible against leaf background. ........, Wild Gooseberry Branch showing 36 37 40 42 45 48 49 51 55 57 60 61 64 73 77 79 LIST OF ILLUSTRATIONS PAGE young green Walking-sticks (Diapheromera femorata) on the upper surface of the leaves. Dune landscape, showing habitat of Orange-tipped Butterfly. Initial drawing . . . . . . , Orange-tipped Butterfly (An- thocharis .genutia), resting on flowers of Arabis lyrata. Col- ored plate. Datana Moth. Tiikel denise, Two Moths (Datana contracta) . Moth (Datana angussi) viewed from above, showing markings in simulation of a dried, rolled leaf . 2... 1... Datana Caterpillars grouped at the top of a branch in sim- ulation of a flower. Geometrid Moth. Initial a Acontia and Stenoma Moths. Initial drawing . : Geometrid Larva on iwc of Sassafras... 2... 1. Moth (Acontia erastriodes) and bird excrement which it’ re- sembles . . .. . . Moth (Stenoma eilnanaidy on upper surface of Strawberry Dieahe: 5.4. ee hye. Re Catocala Larva blending with the color of atwig. Initial drawing Weevil on Oak Bark. Initial photograph by C. T. Hills . Thread-legged Bug and Walking- stick. Initial photographs . Bumble Flower Beetles and Oak Trees. Initial drawing Bumble Flower Beetle and Bumblebee. . . . 2. 2... Schizura Caterpillar. —_ Initial photograph... . 1.2... . Case of protective resemblance both in form and color — the caterpillar Schizura ipomee feeding on dogwood leaf. . 81 83 84 86 87 89 91 93 94 95 96 97 99 . 101 . 105 . 107 109 110 - 111 LIST OF ILLUSTRATIONS PAGE Example of protective resem- blance — green caterpillar feed- ing on leaves of wild gooseberry . Boneset and its butterfly guests. Initial drawing . . 2 2. es . Caterpillar of Viceroy Butterfly on leaf of Heart-shaped Willow .......... Monarch Butterfly (Anosia ple- zippus) above, with its mimic species, the Viceroy (Basilar- chia disippus), below, visiting Boneset Flowers... .. . . Viceroy Caterpillar about ready to pupate Viceroy Pupa. . 2... 2... Robber-fly (Dasyllis sacrata) in pursuit of a Syrphus Fly. Initial drawing Robber-fly (Dasyllis sacrata) on Sassafras Leaf Landscape showing habitat of Flower Flies. Initial drawing. Robber-fly (Dasyllis _ sacrata) with an insect which it has just caught... . Purple Aster with Moth (Plusia simplex) and Drone-fly (Eri- stalis tenax). Colored plate . . Viceroy Butterfly Painted Lady Thistle ... Painted Lady or Thistle Butterfly (Pyrameis cardut) Saddle-back Larvee (Sibine sti- mule) on Witch-hazel Leaves . Row of Saddle-back Caterpillars. Green Caterpillar of the Turnus or Tiger Butterfly. ..... Male Papilio turnus Butterfly visiting the flower of the Red Butterfly and Glover: Ha Bee ee Cresphontes Caterpillar and Butterfly. Initial illustration. Caterpillar of Papilio cresphontes on its food plant, the three- 113 120 121 123 125 126 127 129 130 . 131 132 133 . 189 141 143 144 145 147 150 | xv PAGE leaved hop tree. Photograph by Dr. James Walker Puss-moth Caterpillar in quies- cent attitude. 2... 2... Puss Caterpillar (Cerura multi- scripta) on Willow Leaf, in state of excitement, displaying the whip-lashes at the end of the body... 2... Moth (Achemon sphinx) . . . Sphinx Caterpillar (Pholus ache- mon) on Virginia Creeper Leaf. Moth (Automerisio). . 2... Automeris io Moth with spread wings...) . Hymenopterous Parasite attack- ing Sphinx Caterpillar. . . Wild Carrot Blossoms. photograph... 2... 1, Wild Carrot (Daucus carota), showing an Ambush Bug (Phymata wolffii) near the middle of the flower with a captured fy... 2... Acorn with ant tenants. Initial drawing... 1... Parasitic Wasp (nailines rufi- pes), Cocoon, and Woolly Bear Host. Initial drawing... . Ant-lion Pit, and Adult Ant-lion on Milkweed. Initial drawing Ant-lion andits Cocoon . . . Evening Primrose with Spider (Misumena vatia) in position to trap insects. Initial drawing Spider (Misumena vatia) on Evening Primrose in position to catch insects... 2... Evening Primrose, showing the pink and yellow moth (Rhodo- phora florida). ....... Castle-building Spider on her Castle. Initial drawing. Castle-building Spider (Lycosa domifer) in bottom of her burrow Initial . 152 153 155 . 156 157 160 161 . 163 170 171 AT4 176 177 . 179 182 183 185 . 186 xvi PAGE Castle of Spider. . 190 Jumping Spider (Phidippus mor- sitans) with captured Da- tana Moth ........ 193 Golden Sphex Wasp flying above the opening of her burrow. Initial drawing... 1... Golden Wasp (Spher ichneu- monea) dragging its prey into the burrow ........ Green Meadow Grasshopper (Orchelimum glaberrimum) lay- ing her eggs in stem of burr marigld. ......... Pair of Green Meadow Grass- hoppers (Orchelimum vulgare) on a sedge Jug-making Wasp (Eumenes fra- ternus) in act of building nest. Initial drawing. . 2 1... Completed Nest of Jug-making Wasp (Eumenes fraternus) . Nest of Mud-dauber Wasp, show- ing stored spiders and wasp’s grub. Initial drawing . White-footed Mud-dauber (Try- porylon albitarse) and her Nest. : View of Bluff on Shore of ‘Tigke Michigan, depicting an Out- cropping of Wet Clay where Mud-dauber Wasps obtain Plastic Mud for their Nests. Tabanid Fly... .. . Dog-day Tarvest-fly, Cada, or Lyreman (Cicada tibicen) just emerged from Pupa . . Wild Rose with Rose- nies (Macrodactylus subspinosus). Colored plate... . 2... Oriole’s Nest. occupied by Wrens. Red Squirrel. . 2 2 2... Pair of Maryland Valawthwont Warblers, with Nest. . Landscape, with Goldfinches in foreground. Initial drawing . 195 196 202 205 206 . 207 209 . 213 214 217 218 221 223, . 224 226 LIST OF ILLUSTRATIONS PAGE Goldfinch giving forth his morn- ing song Birds and Blue Racer. drawing - Striped Garter Snake . . . Butcher Bird and Yellow Wie bler. Initial drawing . Young Red Squirrel on Walnut Branch. Initial drawing. Red-headed Woodpecker in act of cracking corn. Initial drawing Landscape, showing Swallows. Initial drawing. Nest of Red-eyed Vireo Red-eyed Vireo . Landscape, showing Hawks. Initial drawing . House Wren’s Nest in the Woods occupied by White-footed Mouse. ... .- . : ‘ White-footed Moure. ‘fi the Wren’s Nest as she appeared after bark had been removed. Pair of Baltimore Orioles. Initial drawing . Fate of Young alvenre Oriole hung by Thread of Nest . Golden-crowned Kinglet cap- tured and killed by Burrs of Burdock. Photograph by R. K. Nabours Stag Beetle (Lucanus Initial drawing . Fowler’s Toad (Bufo fateth. Fowler’s Toad, ventral view. Tailpiece. Landscape, howind Tada Bird and Nest. Initial drawing. Indigo Bird on Nest in Dogwood Bush ...... Nest of Chewink . Male Chewink, or Tawies (Pinile erythrophthalmus) . Young Robins. I witied i aniks Field Sparrow, with Nest and Young Bird Blue Taiciel Night dama). . 227 . 229 231 235 . 236 238 . 242 » 24k . 245 . 246 . 248 250 252 . 253 . 255 256 257 259 . 260 . 261 263 . 264 265 LIST OF ILLUSTRATIONS PAGE View at Edge of Oak Forest in Late Summer ....... Black-eyed Susans, with insect PWS 6% oe eo UK ae Tree-hoppers (Publilia cava)... lL, Dragon-fly (Sympetrum mum)... .....00.., Prison ties, dian junius and Aeschna constricta. . . 281 Dragon-flies at the border of the pond. bers Wild Honeysuckle... .... A Brook, the habitat of the red- bellied minnow (Chrosomus erythrogaster) and the black- nosed dace (Netropis megalops) Plant and Insect Association of the Meadow in September — a Field Thistle, Carduus species, with some of its insect visitors. Colored plate . . 286 Mourning Dove. Initial drawing 290 Male Texan Katydid. Colored plate . Varied-winged Tiseus (Arphia xanthoptera) ........ Geometrid Moth (Xanthotype crocataria) on Wild Bergamot. Initial drawing . Branch of the Button-bush. . . Pair of Texan Katydids on a sedge. Colored plate . 296 Landscape in the sand dunes, showing habitat of striped lizard . . Green Bullfrog (Rana catisbint). con- 276 viet- 279 282 283 285 Colored plate... ..... 300 Blow Snake in sleeping attitude . 300 Beetles. 2... . 301 Crickets (MN. snobs Hiacahoal. 302 Beetle visitors to the Eetitesie light — eyed-elater (Alaus ocu- latis), click beetle, stag beetle (Lucanus dama), and longicorn beetle. . . . . . . 303 xvii PAGE Branch of Button-bush (Cepha- lanthus occidentalis), showing the flower and visiting bumble- DBCS sso Gavan de ster ts a Boke Jumping Mouse (Zappus hud- sonius). 2... Robins. Initial drawing. . . Brown Thrasher... .... Ruby-throated Humming-bird . Hermit Thrush Flicker. 2... 2. Map of Great Lakes Region, showing former glaciated View on Des Plaines River. Landscape, showing habitat of Orthopteran life... .. . Outline tracing, showing habitat of various species of grass- hoppers mentioned in text. Landscape, showing habitat of Orthoptera in the rear of author’s grounds... .. . Male Texan Katydid (Scudderia texensis). Colored plate . . Eggs of Texan Katydid in Leaf of Goldenrod Striped Meadow ne (Xiphidium fasciatum) . Home of the Katydids Pair of Forked-tailed Katydids (Seudderia furcata) on grass plant : Pair of Slender Conachesd! Grass- hoppers (Conocephalus attenu- atus) on goldenrod. ... . Young (Nymph) Cone-head Grasshopper (Conocephalus ro- bustus), showing stage just before the last moult . . . Carolina Locust (Dissosteira caro- lina) Carolina Locust which has been killed by a fungus disease. . Sprinkled. Locust (Chlealtis con- spersa). 305 307 . 308 308 308 313 314 319 . 320 325 - 325 329 . 328 331 . 332 . 333 835 339 . 341 343 . 345 xvill PAGE Pair of Varied-wing Locusts (Arphia xanthoptera) Blatchley’s Locust (Mulanontua blatchley?) Two-striped Locust (Mr lisnempliay bivittatus) : Long-horned Tacnst.. : Mottled Sand Locust (Selena: gemon wyomingianum) . Boll’s Locust = (Spharagemon boll) Clear-wing Locust. pellucida) ; Leather-colored oe (Schis- tocerca alutacea) . Short-wing Brown Laseust “(Ste- nobothrus curtipennis) . Clouded Locust (Brasppectonsline sordidus) . a Grass Stems, Segue dicwtions, the drink of grasshoppers. Initial drawing . . . Mole Cricket (Giyliniclne “one: alis); long-wing form . Striped Meadow Cricket . Stems of blackberry, horsewood, and goldenrod, stripped of their leaves to show the holes made by the striped meadow cricket (Oecanthus fasciatus), during oviposition Pennsylvania Field (Gryllus pennsylvanicus) . Night home of the Katydids. Initial drawing . . Female Ohlong-staved. Katydid (Amblycorypha oblongifolia) on Dandelion . (Camnula Cricket 353 355 . 857 361 . 363 . 365 367 369 371 373 375 . 377 . 379 . 381 . 386 388 . 389 LIST OF ILLUSTRATIONS PAGE Texan Katydid as viewed at night on flower of horse mint. Pair of Oblong-winged Katydids (Amblycorypha oblongifolia) on monkey flower (Mimulus rigens) Short-winged Green Locust (Di- chromorpha viridus) . ‘ Landscape, ‘showing habitat of short-winged green locust. Quaker, or Sulphur-winged Lo- cust (Arphia sulphurea) Landscape in the dune region, showing typical habitat of quaker locust. @. 48 View, showing habitat of reid locust . 6b BT eae Pasture — Locust (Orphuella speciosa) . Short-horned Toast (L. wptial brevicornis) . Home of the shits henitael lacus Green-legged Locust (Afeclanoplus viridipes) . Greenstein. Cactus: (Chortos phaga viridifasciata) . Landscape in the dune region in April, showing habitat of gran- ulated grouse locust . Row of Granulated Grouse fin: custs (Tetrix granulata), show- ing the median striped form . Row of Ornate Grouse Locusts (Tetrix ornata), showing many color forms.and hybrids . Pennsylvania Cockroach (Isch- noptera pennsylvanica) . Lesser Locust COlatmoplas ih lanus) . . 390 391 393 . 394 . 397 398 . 399 401 403 405 407 . 409 411 412 . 412 416 - 417 I. EVOLUTION AND NATURAL SELECTION INTRODUCTION Mammals Birds f000e 3500 R epti les 3000 Amphibians 700 | (Fishes ‘\ 13000 Insects Arachnida ~ 4000 200,000 — 1,000,000 ™ / Crus "ECL ae elids ottfer. tint EN Thread Worm: L Flat Worms Worm SG Coelenterates Porifera ,, Molluscoidea 1200 Protozoa 4000 Nature Sketches in Temperate America I. EVOLUTION AND NATURAL SELECTION T is my purpose to confine this brief historical sketch to some of the salient features of the theory of natural selection as applied to organic life. I shall attempt to show the presumed process by which organisms have changed and become modified into what are termed species. In so doing, I have stated some of the opinions of the principal workers in this field of biological science. Before the time of Linneus the grouping of animals and_ plants was not founded upon any useful scientific plan, and it remained for him to bring forth system out of chaos. The system which he introduced comprised the grouping of animals according to their resemblance, both in external appearance and anatomi- cal structure. This laid the foundation of systematic arrange- ment of animals which grouped them into class, order, genus, species, and varicty. Until recently the majority of natural- ists believed that species were unchangeable productions and had been separately designed and created: On the other hand, some of the earlier naturalists believed that species underwent modification and that the existing forms of life were the descendants of preéxisting forms.' Passing over the allusions made to the subject by the earlier classical writers, we find that Lamarck was the first whose conclusions on the subject excited much attention. In his published views in 1809 he upholds the doctrine that all species, including man, are descendants from other species. He was the first who aroused attention to the probability of all change in the organic as well as the inorganic world being the result of natural causes, and not miraculous interposition. With respect to the means by which modification of animals was 1In this epitomized sketch I have borrowed freely from Darwin and the various other writers cited in the text. 3 4 NATURE SKETCHES IN TEMPERATE AMERICA brought about, he attributed something to the direct action of the physical conditions of life — something to the crossing of already existing forms, and again, much to the use and dis- use of parts—that is, the effect of habit. To this latter agency, says Darwin, he seemed to attribute all the beauti- ful adaptations of nature, such as the long neck of the giraffe for browsing on the branches of trees. He also believed that all forms of life tend to progress, and in order to account for the existence of the present day simple forms of life, he main- tained that they were spontaneously generated. Erasmus Darwin and Herbert Spencer held similar views, namely: that the effect of habit or increased use of structures leads to increase of their functional efficiency. These functionally produced modifications were supposed to be transmitted by inheritance. Following Lamarck were Wells, Saint-Hilaire, Herbert, Grant, Matthew, Von Baer, and others. But we find that Darwin was the first to make the subject of evolution one of universal interest. “‘ With one mighty stroke he released bi- ology from the thraldom of supernaturalism, and the sciences all the way up to psychology have experienced a wonderful renaissance. To unveil that sacred mystery of mysteries and reduce it to the level of natural law was a shock to all Chris- tendom.”! In the place of special creation he set up pro- gressive evolution through the operation of natural law. SPECIES In simple terms we speak of one of the higher animals as belonging to a species. This species is associated in the mind as having represented in its inherent ancestral make-up cer- tain characters of genus, order, family, and kingdom, each of the characters being more and more fundamental as it goes back in its ancestral pedigree. Linnzus established the use of two names to apply to a species, one for the genus and one to designate the species. Modern science recognizes this method of naming species as the bionomic system of nomenclature. Romanes” gives several definitions of species according to 1 Whitman, “‘ Congress of Arts and Sciences, Universal Exposition, St. Louis,” Vol. V. 2 “Darwin and After Darwin,” Part II, p. 231. EVOLUTION AND NATURAL SELECTION 5 the interpretations of naturalists, but the most satisfactory one ~ is as follows: “A group of individuals which, however many characters they share with other individuals, agree in present- ing one or more characters of a peculiar and hereditary kind with some certain degree of distinctness.”” Or another defi- nition of a species may be: A group of individuals bearing | close resemblance and primary relationships to each other. These resemblances include similarities even in minute struc- ture, yet varying and occasionally mutating. Those species living to-day are the latest surviving end product in the evolution of organic life. Individuals of a species interbreed freely. It has been held that one of the distinguishing points of species is that when they are crossed the resulting hybrid offspring are not fertile, but experimen- tation and observation have shown that in plants and animals this test of species does not hold good. Organisms are sensi- tive in their organization and respond to their environment, and this response to the surrounding influence is supposed to set up a tendency to vary. No two individual animals or plants are exactly alike. Systematic species as determined by eminent authorities are as a rule compound groups, often made up of two or three elementary types, and in some cases they comprise numerous constant and well-defined forms. The subdivisions of a species are distinguished from each other by more than one character, often by slight differences in nearly all their organs and qualities, and are designated elementary species. It is very difficult to estimate systematic differences on the ground of comparative studies alone, on account of the great number of varieties of the supposed type. The type from which a new species is described is to a certain extent only tentative, the final judgment in regard to it being more exactly determined only after direct experi- mental breeding. A mutation is usually rare and is often confined to one individual, while varieties are numerous in individuals. The difference exhibited by a sport may amount to a sudden, well-marked change, and present some modi- fication strictly different from the parent type. A genus is an assemblage of species presenting many fundamental characters in common. Some genera are clearly definable, 6 NATURE SKETCHES IN TEMPERATE AMERICA but others are not so clearly separated and are sometimes divided into subgenera, which is the lowest definable group of species. In zodlogy the phylogeny, or descent, of only a portion of the groups of animals has been definitely ascertained, but the diagram from Galloway gives an approximate numerical relation of the groups as they exist on the earth. (See diagram facing first page of text.) STRUGGLE FOR EXISTENCE In the past organic forms were recognized as species when intermediate forms were absent. When these connecting forms were living or were found in the fossil state, naturalists usually regarded the whole series as varieties and named all the members of it as belonging to the same species. In the naming of species they designated cases where connecting forms have not been observed. In the systematic divisions of plants and animals in groups higher than species, such as genera, families, and orders, grada- tions have been traced which show these divisions should be regarded as conventional. Although the pre-Darwinian students of nature recognized gradation among the groups of organisms, in the case of species they supposed them to be the miraculously created units of organic life, in contrast with the present conception that they are the product of natural evolution or gradual transmutation. Wallace states that so far as observation goes “every species has come into existence coincident both in space and time with preéxisting and closely allied species.” Geo- logical evidence shows that extinct species which now occur only as fossils on any given geological area, resemble the species still living upon that area. It is obvious that the vast hordes of animals have a great struggle for existence, and it is to explain the philosophy of how these animals maintain themselves upon the earth, and the causes operating in perpetuating their lives, that the the- ory of natural selection is propounded. Darwin says:! “All organic beings without exception tend to increase at so high 1“ Origin of Species.” EVOLUTION AND NATURAL SELECTION 7 a ratio that no district, no station, not even the whole sur- face of the land or the whole ocean would hold the progeny of a single pair after a certain number of generations. Even slow-breeding man has doubled in twenty-five years, and at this rate, in less than a thousand years, there would literally not be standing room for his progeny. In the same way all through nature every organic being may be said to be striv- ing to the utmost to increase its numbers. The result is an ever recurrent struggle for existence. It has been truly said that all nature is at war. The strongest ultimately prevail, the weakest fail, and we well know that myriads of forms have disappeared from the face of the earth.” Here we again recall the classic words of Darwin: ‘When we look at the plants and bushes clothing an entangled bank, we are tempted to attribute their proportional number and kind to what we call chance. But how false a view this is. What a struggle must have gone on during long centuries between different kinds of trees, each annually scattering its seeds by the thousand. What war between insect and insect, between insects, snails, and other animals, with birds and beasts of prey all striving to increase, all feeding on each other or on the trees, their seeds and seed- lings, or on the other plants which first clothed the ground and thus checked the growth of the trees. But the struggle will almost invariably be more severe between the individuals of the same species, as they frequent the same districts, require the same food, and are exposed to the same dangers.” He further maintained that in all nature we see a strong tendency to variation. Now if any organic being varies even in a slight degree owing to change in environment, of which we have abundant geological evidence; if in the long course of ages inheritable variations ever arise in any way advantageous to any being under its exceedingly complex and changing rela- tions of life, it would be a strange fact if beneficial variations never arose, seeing how many have arisen which man has taken advantage of for his own profit and pleasure. If, then, these contingencies ever occur, then the ever recurrent struggle for existence will determine that those variations, however slight, which are favorable -shall be preserved or selected, and those which are unfavorable shall be destroyed, and from the strong 8 NATURE SKETCHES IN TEMPERATE AMERICA principle of inheritance the selected variety will tend to propagate its new and modified form. Darwin says: “This preservation, in the battle of life, of varieties which possess advantages in structure, constitution, or instinct, I have called natural selection.’ Spencer has well expressed the same idea by the survival of the fittest. Darwin placed emphasis on the point that natural selection does not imply conscious choice. For brevity’s sake he some- times spoke of natural selection as an intelligent power in the same way as astronomers speak of the attraction of gravity as ruling the movements of the planets. Moreover, he often personified nature, but he adds: “I mean by nature only the aggregate action and product of many natural laws, and by laws the ascertained sequence of events as ascertained by us.” “Under domestication we see much variability caused, or at least excited, by changed conditions of life. Variability is governed by many complex laws, by correlated growth, com- pensation, the increased use and disuse of the parts,! and the definite action of the surrounding conditions, such as climate and food supplies. There is no question but that our domestic productions have been modified and these modifications have been inherited for long periods. Variability is not actually caused by man, but the organism is exposed to new conditions of life, and nature acts on the organization and causes it to vary.” But man can and does select variations given him by nature and thus accumulates them in any desired manner. “The key is man’s power of accumulative selection, nature gives successive variations, man adds them up in certain directions useful to him. It is the magician’s wand by means of which he may summon into life whatever form and mould he pleases.” Taking the domestic pigeon, for example, he was able to trace its ancestry to the wild rock pigeon which is still extant. It is certain that man can select individual differences in a breed so slight as to be unappreciated except to an educated eye. Man can produce a great result by his methodical and uncon- scious means of selection. 1 The variations caused by increased use and disuse of parts are not now considered by many investigators to be inherited. EVOLUTION AND NATURAL SELECTION 9 “But man can act only on external and visible characters. Nature cares nothing for appearances, except in so far as they act on every internal organ, on every shade of constitutional difference, on the whole machinery of life. Man selects only for his own good, nature only for that of the being which she tends. Man keeps the natives of many climates in the same country —he feeds the long and short beaked pigeon on the same food. He often begins his selection by some half monstrous form, or at least by some modification prominent enough to be plainly useful to him. Under nature the slightest difference of structure or constitution may well turn the nicely balanced scale in the struggle for life and so be preserved.” “How fleeting are the wishes and efforts of man, how short his time, and consequently how poor will be his results compared with those accumulated by nature during whole geological periods! Can we wonder then that nature’s productions should be far truer in character than man’s productions; that they should be infinitely better adapted to the most complex con- ditions of life and should plainly bear the stamp of far higher workmanship? No breeder doubts the strong tendency to inheritance. That like produces like is his fundamental belief. Every one has heard of strange and rare deviations of structure being inherited. Now if these are freely ad- mitted to be inherited, how much more are the less strange forms inherited.” Darwin again says the laws governing inheritance are for the most part unknown. “Perhaps the correct way of viewing the whole subject would be to look at inheritance as a rule and non-inheritance as an anomaly. The whole subject of inheritance is wonderful. When a new character arises, whatever its nature may be, it tends to be inherited, at least in a temporary and sometimes in a per- sistent manner.” Castle has recently stated: ‘Every. new individual arises out of material derived exclusively from its parents. This is the basis of heredity. But it does not follow that the new individ- ual will resemble its parents merely. It may resemble remote ancestors more strongly than either parent. For it repre- sents a combination of materials or of qualities derived 10 NATURE SKETCHES IN TEMPERATE AMERICA from the two parents, and it is possible that neither parent may manifest all the peculiarities which it transmits to the offspring. For the parent is made up of two distinct parts, its own body and the reproductive substance con- tained within that body, and the two may not be identical in character.” The checks to inheritance as far as we know them are: firstly, circumstances hostile to the peculiar characters in question; secondly, conditions of life incessantly inducing fresh variability; and, lastly, the crossing of distinct varieties during some previous generation, together with reversion; that is, the tendency in the child to resemble its grandparents, more remote ancestors, or some distant member in a collateral line instead of its immediate parents. A familiar example of reversion is the horns appearing in the young of hornless cattle. The offspring may present inter- mediate characters between those of the parents, which is known as blended inheritance; or the offspring may be more extreme than either parent, which is known as intensified inheritance; or, lastly, the offspring may exhibit characters dif- fering from those of either parent, which is known as hetero- geneous inheritance. In the case of sterile offspring, such as the mule, of course they are self-exterminating. Mendel brought forth the principle that the hybrid produces germ-cells like those of its parents in about equal numbers, and the character of its offspring will be dependent on the chance way in which these germ-cells are paired in fertilization. When the parental characters are preserved in the hybrids, that is unaltercd, it is known as alternative inheritance. Castle affirms that size variation is apparently continuous and its inheritance blending, while color variation is discon- tinuous and its inheritance is governed by Mendel’s law.! Brooks reminds us that in popular language specific stability may be said to be due to inheritance and specific mutability to variation. But in this connection these words have only a loose meaning, in so far as they convey the impression that the stability and mutability of species are antagonistic to each other. These terms are unfortunate, for we have good ground 1 Popular Science Monthly, May, 1910, p. 426, EVOLUTION AND NATURAL SELECTION 11 for believing that they are only contrasted aspects of the same phenomenon. For stability of species is due to survival in the same way that mutability is. EvoLution anp INSTINCT An action which requires experience to enable us to perform it, says Darwin, when performed by an animal, more espe- cially by a very young one without experience, and when per- formed by many individuals in the same way without their knowing for what purpose it is performed, is usually said to be instinctive. A little dose of judgment or reason, says Huber, often comes into play even with animals low in the scale of life. Instinct has been defined as hereditary habit (behavior), comprising an element of transmitted experience. In all cases where instinct becomes complex or refined we seem com- pelled to accept the view that its origin is to be sought in con- sciously intelligent adjustment on the part of the ancestors. Many of the lower animals exhibit instinctive actions, such, for instance, as a spider-spinning its web, a bird building its nest, and the beaver building a dam, these actions being per- formed the first time the animal tries almost as well as when it is older and experienced. Spencer supposed that intelli- gence first arose through the multiplication and codrdination of reflex actions, and although many of the simple instincts grade into reflex actions, and can hardly be distinguished from them, yet the more complex instincts seem to have arisen inde- pendently of intelligence. Instinct has been described as being automatic obedience to the demands of external conditions. As these conditions vary with each kind of animal, so must the demand vary, and from this arises the great variety actually seen in the instincts of different animals. With others, instinct has been regarded as the natural survival of those methods of automatic response which were most useful to the life of the animal, the individuals having less effective methods of reflex action having perished, leaving no offspring. As the mental qualities of animals vary and as instincts vary slightly in a state of nature, and as instincts are of the highest importance to each animal, there is no real difficulty under changing conditions of life, says Darwin, in “natural 12 NATURE SKETCHES IN TEMPERATE AMERICA The large parasitic Ichneumon Fly (Thalessa lunator), having a long oviposttor for drilling in trees. With extraordinary instinct it pierces the wood and deposits an egg 1 an the burrow of the Tremex larva. See page 13. EVOLUTION AND NATURAL SELECTION 13 selection accumulating to any extent slight modifications of instinct which are in any way useful.” A remarkable example of perfected instinct is shown in one of the hymenopterous insects known as Thalessa (see illustra- tion). This is an ichneumon fly having the end of the body pro- vided with a long ovipositor with a chisel-like extremity. With this instrument she bores into the solid wood of a tree and with great precision strikes the burrow of the Tremex larva. After reaching the burrow she deposits an egg, which, soon after hatch- ing into a larva, crawls along the burrow and attaches itself and feeds on the body of its victim. ForMATION oF NEw SPECIES It has been lately maintained by DeVries that species can come into existence within the space of a man’s life- time. This has been observed to take place in the evening primrose in a state of nature. Darwin maintained that natural selection acts by accumulating slight successive favor- able variations. It can produce no great or sudden modifi- cation. But, according to DeVries, species have not arisen through gradual selection continued through hundreds of thousands of years, but through sudden, though small, trans- mutations, or steps. In contrast with fluctuating variations, which are changes in a linear direction, the transformations called mutations diverge in new directions without apparent definite direction. MacDougal, after considerable experimentation, has gone so far as to say: “Having ascertained at what time in the life period of the individual mutations occur, I have been so fortunate as to secure results demonstrating that mutations may be induced in a species not hitherto active in this respect, and that it is possible to call out new species by the intervention of external agents during the critical period.” ! ; Of DeVries’ views on this subject Whitman says: “The so-called mutations of the primrose are undoubted facts, but two leading questions remain to be answered. First, are these ‘1 “Heredity and the Origin of Species,” 1905, p. 31. 14 NATURE SKETCHES IN TEMPERATE AMERICA mutations now appearing, as is claimed, independently of variations that took place in an earlier period in the history of these plants? Secondly, if species can spring into existence at a single leap without the assistance of cumulative variations, may they not also originate with such assistance? That varia- tion does issue in new species and that selection is a factor, though not the only factor, in determining results is in my opinion as certain as that grass grows, although we cannot see it grow. It is then after all the slight individual differences that suffice for the work and are probably the sole differences which are effective in the production of new species.” Furthermore, Tower says: “Of late there has grown up, since the publication of DeVries’ work, a tendency to ascribe to ‘mutation’ a far greater importance, and to a considerable extent to substitute that process for all others in evolution, even though DeVries distinctly points out that ‘mutation’ is complementary and not antagonistic to natural selection, and that the two are necessary in evolution — that is, ‘muta- tion’ explains the origin of variations in evolution, and natural selection their preservation.” + Weismann maintained that there are three principal stages of selection: that of personal selection as held by Darwin and Wallace, that of histonal selection as upheld by Roux in the form of the struggle of the parts, and, finally, that of germinal selection, the existence of which he endeavored to establish. He called the reproductive substance the germ plasm, and he maintained that this substance is distinct from the body and the influences that modify the character of the one do not necessarily modify the character of the other. These are the supposed factors that codperate to maintain the forms of life constantly capable of life. It may be interesting to note that the study of variation has been aided considerably by mathe- matical science, that is, by the use of statistical measure- ments. This is accomplished by taking.a series of hundreds or thousands of individuals of a species in a state of nature and, by making careful measurements of some of the more impor- tant structures of the animal and reducing them to figures, Investigation of Evolution in Chrysomelid Beetles of the Genus Leptino- tarsa. EVOLUTION AND NATURAL SELECTION 15 making deductions accordingly. In this way it has been shown by Galton that certain individuals of a species, represented by the mean measurements, survive in the struggle for existence, while those individuals which depart somewhat radically from this type, as represented by the maximum and minimum, are eliminated in the struggle for existence. This law was earlier known to Quetelet! and now bears the latter’s name. This law of trial by error has an important bearing on the question of evolution, especially on the origin of species, for it will be remembered that DeVries says the origin of species has been brought about by the sudden though slight changes that have been acquired and transmitted to the offspring. According to Quetelet’s law, mutations would seemingly not be preserved in the struggle for existence (see under “ Varia- tion”’). The question may be asked: If the tendency to variation is so great, why is it that some simple animals from the first apparently remain in the same condition? Why have not the more highly developed forms supplanted and exterminated the lower ones? In answer to these questions Darwin says ‘that natural selection does not necessarily include progressive development, it only takes advantage of such variations as arise and are beneficial to each creature under its complex relation of life. He adds: “What advantage would it be to an earthworm or infusorium to be highly organized? If it were no advantage these forms would be left by natural selection unimproved, or but little improved, and might remain for indefinite ages in their present lowly condition. In some cases variations or individual differences of a favorable nature may never have arisen for natural selection to act on and accumulate.” There must arise something of a selective value, says Romanes, for natural selection to act on. Darwin further says: “In no case has time sufficed for the utmost possible amount of develop- ment. Nevertheless, low and simple forms will long endure if well fitted for their environment, namely, simple condition of life.” Darwin’s principle explains that selection takes place between individuals, while the mutation theory decides between whole species, and ultimately it is simply the ability for existence ! Discovered in 1846. 16 NATURE SKETCHES IN TEMPERATE AMERICA under given conditions that decides the permanence of a form. Variation is sometimes orderly tendency, — that is, there is definite variation, — or the species forming variability and mutability is indeterminate in direction. In either case it is not teleology, or adaptation to purpose, which was so effectually eliminated by Darwin. We find there is apparent difficulty for natural selection to account for the incipient stages of useful organs, and here orthogenesis attempts to remove this obstacle. The name was originally introduced by Haache, and later, among others, was championed by Eimer. The latter’s work was dominated by a desire to show the inheritance of acquired characters. Whitman ! says that “without the assistance of some factor having more continuous directive efficiency, selection would fail to bring out of the chaos of chance variation or kaleidoscopic mutation, such progressive evolution as the organic world reveals. In order to show such a factor is essential, and that it is actually present, supplying the indispensable initial stages, and holding the master hand in the general direction of evo- lution, demonstrative evidence is, of course, required. Such . evidence lies in the history of specific characters.” After pains- taking breeding experiments with pigeons covering many years, Whitman demonstrated by making phylogeny his guide as a starting point, that the orthogenetic process is a primary and fundamental one. By his researches, he found it compara- tively easy to thread his way through the maze of color patterns existing among five hundred or more species of pigeons, and even to trace affinities farther back in the bird world. Of the orthogenetic process he further says: ‘We find unlimited opportunity for the play of natural selection, escape the great difficulty of incipient stages, and readily understand why we find so many conditions arising and persisting without any direct help of selection.” Osborn? has recently given the influences which govern evolution as follows: “The life and the evolution of organisms continuously centre around the processes which we term 1“The Problem of the Origin of Species,” Congress of Arts and Science, Universal Exposition, St Louis, 1904. 2 Osborn in “Fifty Years of Darwinism,” 1909, p. 238. EVOLUTION AND NATURAL SELECTION 17 heredity, ontogeny, environment, and selection; these have been inseparable and interacting from the beginning; a change introduced or initiated through any one of these factors causes a change in all. First, that while inseparable from all the others, each process may in certain conditions become an initia- tive or leading factor; second, that in complex organisms one factor may at the same time be initiative to another group of characters, the inseparable action bringing about a continuously harmonious result.” VARIATION Since Darwin’s “Origin of Species” and especially in the last decade since DeVries’ “‘Mutationstheorie” appeared, the statistical, quantitative, and experimental study of variation has received a new impetus, and there has developed a “biometric school.’”’ Experimental investigation of variation has made more exacting the study of the problem, but as yet no fundamental laws have been proved regarding the real causes of variation. As soon as a hypothesis is advanced, it is subjected to painstaking test and analysis, principally by breeding experiments of plants and animals. Variations dependent on environment or use are not now supposed to be inherited, while on the other hand, new characters are trans- mitied from parent to offspring. On this basis a classification of variations is formed on their heritability. According to Jordan and Kellogg‘ variations may be either congenital or acquired; that is, may be such as are apparently determined in the organism at conception, or such as are imposed on it during its development by the influence of extrinsic factors. Or variations may be divided into deter- minate and indeterminate; that is, those (if there really are such) which are apparently controlled by some, to us unknown, influences and by these influences confined to certain lines or directions of change; and, on the other hand, those which are apparently wholly accidental, or rather which may represent any conceivably possible line or kind of change. Finally, variations may be distinguished as to their general character as continuous and discon- 1 “Evolution and Animal Life,” pp. 140, 141. 18 NATURE SKETCHES IN TEMPERATE AMERICA tinuous; that is, variations occurring irregularly, mostly large and comparatively rarely, and small abundant variations occurring in gradual series. Among the former are to be ranked the occasional sports and monsters familiar to breeders, while in the latter, Darwin believed himself to have at hand the necessary, ever-present materials to serve natural selection as a basis for species transformation. Hence the slight, but abundant and ever-present, fluctuating, continuous variations are often called ‘‘ Darwinian variations.” The law of Quetelet applies solely to the Darwinian variations, The law is “that these variations occur according to the law of probabilities (or law of error); that is, that the slightest variations away from the modal or average type will be the most abundant, and that the number of varying individuals will be progressively less the farther away from the modal type the variations of these individuals are.”’ DeVries maintained that species have arisen without the aid of natural selection; the actual production of species being due to saltation or mutation quite in contrast with the gradual transmutation of Darwin.! This conception of species formation is different from the theories of Nageli, Eimer, and Cope, who maintained that non-fortuitous and determinate variations were determined by certain causes inherent in life (Nageli), or causes extrinsic to life, but imposed upon it (Eimer). Recently Johannsen has endeavored to interpret by experi- mental investigation those slight variations that seem to be independent of environment, which the biometric students call “‘frequency polygon.” Davenport,? in reviewing the work of Johannsen, says: “The biometric ‘school’ laid stress on this sort of variation and held that by selective breeding from the extreme variants through many generations an indefinitely wide departure from a starting point might be effected. This DeVries denied, but held that, while such selection might lead to a certain departure from the mode, the degree of such a departure was restricted through a strong regressive tendency. Here 1 Natural selection determines the future existence of the form in either case. 2 Sctence, N. S., XXX, 1909, p. 852. EVOLUTION AND NATURAL SELECTION 19 Johannsen steps in, analyzing more completely this result of breeding from the extremes of the frequency polygon.! “The fundamental principle of Johannsen is that an ordinary frequency polygon is usually made up of measurements of a characteristic belonging to a non-homogeneous mass of indi- viduals; that it is really analyzable into several elementary masses each of which has a frequency polygon of its own. In each elementary polygon the variation is strictly due to non-inheritable somatic modifications, selection of extremes of which has no genetic significance. But the selection for breeding of individuals belonging to different elementary polygons, lying, say, at the extremes of the complex, may quickly lead to an isolation of these elementary polygons, the constituent individuals of which reproduce their peculiarities as distinct elementary species. Thus Johannsen holds that not only do individuals with qualitatively dissimilar characters belong to distinct elementary species, but often such as are only quantitatively unlike. The complex variation-groups are called by the author phaenotypes, or false types, the elementary variation-groups are genotypes, or genetic types.” Utiniry anp Natural SELECTION Perhaps no principle has created more discussion than that which Darwin so earnestly impressed upon us, namely: that no special organs, no characteristic form of markings, no peculiari- ties of instinct or habit, no relation between species or races can exist but must now be, or at a previous time have been, useful to the individual or species which possesses them. Natural selection cannot possibly produce any modification exclusively for the good of another species, although they often take advantage of beneficial structures. Darwin also maintained that if it could be proved that any part of the structure of any one species had been formed for the ex- clusive good of another species, it would annihilate his theory, for such could not have been produced by natural selection. Wallace tells of the varied ways in which the coloring and form of animals serve for their protection, 1For further study of so-called frequency polygon consult ‘‘Davenport’s Methods,” second ed., 1904. 20 NATURE SKETCHES IN TEMPERATE AMERICA their strange disguises. The simulation of animals to other objects has been designated as “protective resemblance and mimicry.”