Viisilllljl 1,1, ALBERT R. MANN LIBRARY New York State Colleges OF Agriculture and Home Economics AT Cornell University The original of tiiis book is in tine Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924101523425 A STUDY OF SELECTIONS FOR THE VARIATION AND INHERITANCE OF THE SIZE, SHAPE AND COLOR OF HENS' EGGS A THESIS PRESENTED TO THE FACULTY OF THE GEADUATE SCHOOL 0K CORNELL UNIVERSITY FOR THE DEGREE OF DOCTOR OF PHILOSOPHY BY EARL WHITNEY BENJAMIN 1914, 1920 A STUDY OF SELECTIONS FOR THE VARIATION AND INHERITANCE OF THE SIZE, SHAPE AND COLOR OF HENS' EGGS A THESIS PRESENTED TO THE FACULTY OF THE GRADUATE SCHOOL OF CORNELL UNIVERSITY FOR THE DEGREE OF DOCTOR OF PHILOSOPHY BY EARL WHITNEY BENJAMIN 1914, 1920 CONTENTS PAGE Review of literature 195 Methods of investigation 198 Size character .- 199 Shape character 201 Photographing the eggs for size and shape studies 202 Color character .' 20i Methods common to studies of all the characters 206 Results : 208 Inheritance studies '. 208 Variability of production due to differences between the parent types 208 Inheritance of mean egg type 215 Relation of egg incubated to mean egg type of bird hatched 227 Relation of eggs incubated to types of eggs produced by the respective birds hatched 214 Miscellaneous studies •. 250 Relationship of size and shape of eggs 250 Incubation effects of egg type 252 Relative variability of the productions of successive yecirs 253 Variations in types of eggs produced during successive months and years 254 Size character 255 Shape character ' 259 Color character. 262 Variations in types of successive individual eggs 266 Variations in types of eggs produced in different calendar months 267 Relation between vigor of the chick and size of the egg from which it was hatched 269 Relation between male and female weights for chicks of the same age 270 Relation between size of the chick and size of the egg from which it was hatched 271 Discussion of results 305 Summary 307 Acknowledgments 309 Bibliography 310 191 A STUDY OF SELECTIONS FOR THE SIZE, SHAPE, AND COLOR OF HENS' EGGS A STUDY OF SELECTIONS FOR THE SIZE, SHAPE, AND COLOR OF HENS' EGGSi Eakl W. Benjamin The study here reported was conducted from the spring of 1911 until 1919, with the purpose of determining the results that may be obtained by selecting the breeding stock of the domestic fowl, and. the eggs for hatching, in order to change the size, shape, and color of the eggs pro- duced by the offspring. There is a certain type of egg which especially meets the desires of the respective customers in various markets. It is usually not practicable to grade the eggs closely, and it becomes necessary to select and develop the flocks so that the proportion of eggs unsatis- factory to the customer may be reduced to the minimum. The wholesale trade of the New York City market requires the size and shape of the eggs to be such that the eggs are not crowded, but fit snugly, in the fillers of the conamercial thirty-dozen cases; this naeans an egg about 2| inches long and If inches wide, and usually weighing from 2 to 2| ounces when fresh. Shipping only the eggs of proper size and shape insures less breakage, better appearance, and a resulting higher sale value. The New York City market has a special demand for white- shell eggs and will sometimes pay from eighteen to twenty cents a dozen more for eggs having chalk-white shells than for those varying from cream- tinted to brown. REVIEW OF LITERATURE The study of the external characters of eggs seems to date from a com- paratively recent period,, and even at the present time the pubhshed data with respect to these characters are very meager. Tradition tells us (in Horace, Lib. II, st. 4) that the eggs of pullets are longer than those of hens, and that pullets' eggs produce a larger proportion of male chicks than do hens' eggs. This tradition has been developed until many persons believe that long eggs produce cockerels and round eggs produce pullets when incubated. 1 This study completes the work reported in part in a thesis presented by the writer to Cornell Uni- versity in 1912 for the degree of master of science in agriculture, and continued in a thesis presented to Cornell University in 1914 in partial fulfillment of the requirements for the degree of doctor of philosophy. 195 196 Earl W. Benjamin The size and shape of the egg is shown by Curtis (1911 a)^and by Surface (1912) to be due partly to the structure of the oviduct, which may probably be considered an inherited character as claimed by Newton (1893-96). This is in accordance with the view of Thompson (1908). This physical influence on the size and shape of the egg described by Thompson (1908) is denied by Horwood (1909), but without convincing evidence. The shape of the egg seems to depend on its size, according to Curtis (1914 a). The same author shows good correlations between the two dimensions of eggs, and between either of these dimensions and the weight. This agrees with the conclusions of Pearl and Curtis (1916). Curtis (1914 a) claims that the larger eggs are due to a greater relative deposition of egg white, while Atwood (1914) finds indications contrary to this. ^ The size of the egg seems to be affected by the feed, according to Atwood (1914), and the same author shows a marked seasonal fluctuation in the weight of eggs laid, the weight gradually increasing from July to February and decreasing from March to July. , This agrees with Curtis (1914 a) and with F6r^ (1898 b), who claim that the eggs are smaller at both the beginning and the end of the litter. Rice, Nixon, and Rogers (1908) and Riddle (1911) show a striking effect of the amount of food consumed on the number of eggs produced. According to these workers, both the amount of food consumed and the number of eggs pro- duced seem to be variable factors agreeing in their seasonal fluctuations with the size of the egg, as just noted. Curtis (1914 a) also shows a grad- ual reduction in size for the successive eggs in the clutch. Hadley (1919) shows a monthly fluctuation in the egg weight of thirty-nine White Plymouth Rocks Tvhich corresponds closely with the monthly numerical production. He finds also that the percentage increase in egg weight during the two modal months of increased production (April and Sep- tember) is positively indicative of the relative annual numerical produc- tion of the respective birds. .^According to Curtis (1914 a), the size of the eggs increases as the bird matures. Curtis states also that the variations among the eggs produced by individuals were not so great as the variations in the flock's production, and seemed to diminish as the birds matured. This agrees with the 2 Dates in parenthesis refer to Bibliography, page 310. Study op Seliictions for Size, Shape, and CotOR of Hens' Eggs 197 results obtained in a study of the number of leaves to a whorl in Ceratophyllum made by Pearl, Pepper, and Hagle,' and in a later study for egg shape made by Pearl (1909). Similar variations in sparrows' eggs have been observed also by Pearson (1902 b). Stewart and Atwood (1909) report that chicks hatched from pullets' eggs are not so large nor so vigorous as those hatched from the eggs of hens two and three years old. Atwood (1914) mentions this fact as showing that chicks hatct ed from larger eggs are larger and more vigorous than others. It would seem that there is danger here of attributing any possible defect of the embryo due to the inamaturity of the parent, to the smaller size of the agj, which also is due to the immaturity of the parent. The writer does not see proof that a smaller egg produces a smaller and weaker chick irrespective of the maturity and condition of the parent. Pearl and Curtis (1916) found thai the two characters size and shape, as measured by weight, length, and breadth, show different degrees of variability, ranging from the most variable to the least variable in the order named. Pearl and Curtis were able also to strengthen their previous conclusions that the index and the weight are negatively cor- related. They found that dwarf or abnormal eggs do not occur more frequently at the beginning or at the end of the Htter than at other times. During the eight years previous to their study, 5.15 per cent of all the birds kept at the Maine experiment station produced one or more dwarf eggs, and only 3.5 per cent of this 5.15 per cent produced more than two dwarf eggs. Abnormal types of eggs have been reported also by Von Nathusius (1895), F^re (1897 and 1898 b), Herrick (1899, a and b), Hargitt (1899 and 1912), Parker (1906), Patterson (1911), Glaser (1913), Curtis (1914b), Chidester (1915), and Weimer (1918). Some of the abnormahties reported might, of course, prove to be inherited, especially such as the double yolks found by Glaser (1913); however, since this pubhcation is concerned with normal eggs, further discussion of rare monstrosities may be omitted. The coloration of the shells of eggs has long been a subject of interest to oQlogists. According to Newton (1893-96), older birds usually lay darker-shell eggs. Newton says that some of the color is applied to the 3 Variation and differentiation in Ceratophyllum. By Raymond Pearf, Olive M. Pepper, and Florence J. Hagle. Carnegie Inst. Pub. no. 58 : 1-136. 1907. 198 Earl W. Benjamin shell early in its development, while some is added later — as is indicated by the lighter shade of an egg that has been laid prematm-ely, due to some excitement. The intensifying of the pigment with the age of the bird is supposed to continue until she has attained her full vigor, when the tint begins to decline gradually. Newton believes that except for individual differences the pigment is fairly constant in supply. Sorby (1875) found seven substances which in various mixtures are sup- posed to produce all eggshell colors. These substances were oorhodeine, oocyan, banded oocyan, yellow ooxanthine, rufous ooxanthine, a substance giving narrow absorption-bands in the red, and lichnoxanthine. They are said to be closely connected with either haemoglobin or bile pigments. M'Aldowie (1886) and many others have advanced theories as to the cause of variation in eggshell color. The general opinion seems to be that the color is very unstable and variations do occur frequently, and that general tints or colors are inherited. Horwood (1909) gives it as his opinion that coloration of the shells of birds' eggs has absolutely no connection with mendehan principles. According to Surface (1912), the color of eggshells is probably added from glands in the vagina or adjoining parts of the oviduct, and it may reasonably be supposed that a fimction of this nature would be inherited. Such a supposition agrees with the results of Benjamin (1912 and 1914), which are discussed later in this report. All these studies, made by various workers, show conclusively that with respect to ma,ny characters, including size, shape, and color, there is a characteristic type of egg to be accredited to each individual, and that some degree of inheritance has been found to exist. n METHODS OF INVESTIGATION The investigation described in this memoir was begun, in the spring of 1911, by selecting fifty eggs for hatching for each of the follow- ing nine characters — three characters being grouped in each of three selection studies: Size selections Shape selections Color selections Large Long Chalk-white Medium Normal ■ Cream-tinted Small Round Brown-tinted Study of Selections for Size, Shape, and Color of Hens' Eggs 199 The eggs were selected from three-year-old Single Comb White Leghorn hens, and an effort was made to get eggs from hens that consistently laid the type of egg selected. The Single Comb White Leghorn breed was used for the study because, first, it is 'the commonest breed in New York State, and secondly, because it was desired to study these commercial characters of eggs by the use of comrfiercial breeds, and the Leghorn predominates on commercial- egg farms in the United States. The birds used were from the high-producing trap-nested stock of the well-established Cornell strain. SIZE CHARACTER The basis for selecting eggs for the size character was weight. A Harvard balance, equipped with a slide reading to 10 grams in tenths, was used early in the work, but this was later replaced by a special direct-reading balance (fig. 7).* Exact weights were used at first, but later the weights were recorded in 2-gram classes and could be transferred directly for use in the correlation tables. Eggs weighing more than 50 grams and not. more than 52 grams were recorded as 51 grams in weight and were ^grouped in the 50-52-gram class in the correlation tables. The eggs were weighed as soon as possible after they were laid, in order to avoid any serious losses due to evaporation. When it was neces- sary to hold them for some time before weighing, they were kept packed and in a cool, rather moist, place. T^ter January, 1913, the eggs were held in an artificially cooled room at a temperature of from 32° to 40° F. The eggs selected for incubation each year were weighed, as well as all the eggs produced by any of the hens in the size-character studies. In the early part of the work the eggs selected for incubation were also measured and their length and breadth recorded. Just before hatching, the eggs were placed in pedigree trays. The trays used in 1911 were so constructed that it seemed advisable to put into one compartment all the eggs produced by the same hen. If more than one egg in a compartment hatched, it was necessary to use the average of aU the hatched eggs in that compartment, in order to calculate the average type of egg which hatched. This gave a fairly accurate result because, as a rule, all the eggs laid by the same hen are of the same general type. However, as this method allowed the possibility of some error, * Thio balaacc was imported by Corneliua Kahlen, New York City. 200 Earl W. Benjamin Fig. 7. specially designfd direct-reading balance for weighing eggs and ch;cks Study of Selections for Size, Shape, and Color of Hens' Eggs 201 all incubated eggs were individually pedigreed after 1911. For the 1912 and 1913 hatches, the compartmentp of the pedigree trays were made small enough to hold just one egg, and thus it was possible to know from which egg each chick hatched. In the 1914 hatch and after that time, the chicks were satisfactorily hatched in cloth bags. The day-old chicks were weighed on the same direct-reading egg scales as were used for the eggs. After this first weighing the chicks were individually weighed every four weeks on a special type of milk balance, by which the weights could be accurately estimated to 1/100 pound. When these weights were transformed to grams, as was done for some of the correlation tables, the calculation was made by means of the formula, 1 pound = 453.6 grams. In the early part of the work a separate record was made of the vigor of the chicks. SHAPE CHARACTER The basis for selecting eggs for shape was the index figure obtained by dividing the greatest width of the egg by its greatest length p,nd 1 ^m ^Hl Fig. 8. specially designed ratchet micrometers held BY woodworking CLAMP, FOR EGG MEASUREMENTS multiplying the result by 100. The measurements were made by specially constructed ratchet micrometers with a f-inch face (fig. 8).* One micrometer was adjusted for the egg length and one for the egg width. ' These were mantifactured by Brown & Sharpe, Providence, Rhode Island. 202 Earl W. Benjamin Fig. 9. light, and frame for holding eggs, as used for the shadow photo- graphic process The wire circle around tlie liRht was used early in the work to hold a curtain for preventing reflection of light from the sidewalk. The eggs are shown as they are placed on the film ready for exposure. At the riftht is shown the frame used for arranging the eggs in their proper positions The micrometers were held in a wood- working clamp to prevent error due to expansion which might result if they were warmed by .being held in the hand of the operator. All eggs incubated for the shape- character studies, or produced by hens in the shape-selection studies, were measured and the data recorded. PHOTOGHAPHING THE EGGS FOR SIZE AND SHAPE STUDIES It was thought desirable to have some sort of graphic representations of the eggs selected for size and shape, and .to compare these with represen- tations of the eggs that the pullets produced dming the following year. Photography was the first method of representation considered. Since this was very expensive, however, the practice of allowing the shadows of the eggs to fall directly on sensitized photographic paper was adopted.* A sheet of sensitized paper, 9 by 11 inches in size, is slipped into the back of a specially constructed frame, where it is held securely by a wooden support. The sensitized paper is slipped in back of a sheet of stock film glued in the frame; this film, if kept clean, does not hinder the re- production, reflects much of the dif- fused light, and thus prevents the blurring of the shadow.' The eggs are placed on the film as shown in figure 9, and are held in It was necessary to use high-contrast paper for this work, in order to obtain distinct black and wnite tones. ' This stock film is the base used for photographic films before the gelatinous coating is applied. It is transparent. Study of Selections fob Size, Shape, and Color of Hens' Eggs 203 Fig. 10. PHOTOGRAPHIC STUDY OF SIZE AND SHAPE CHARACTERS This shows the appearance of the sensitized paper after exposure under the eggs and subsequent development. A record is made at the time of the exposure, identifying each egg so that, i£ desired, it may be used later in a group with all other eggs laid by the same hen 204 Earl W. Benjamin place by small circles of stock film made by cutting strips of film about 3 inches long and f inch wide and gluing the ends together. These film circles are transparent, thus casting no shadow, and are therefore much more suitable than if made of an opaque substance such as cardboard or metal. When the twelve eggs that are to be reproduced on each 9x11- inch sheet are placed on the film, they are arranged evenly by means of a separate frame shown in figure 9, which divides the 9xll-inch space into twelve equal parts. This frame is removed before the repro- duction is made. After the frame with the eggs on it is in place under the light, the Hght is turned on for an exposure varying with its power and its distance from the eggs. In this study, a 200-candle-power tungsten light, with a special parallel-ray reflector, was used, about 9 feet distant from the eggs, and an exposure of just one minute was required. A red light was used when working with the sensitized paper. After the exposed sheet has been developed, the eggs appear as white outhnes on a black background (fig. 10). ^A key is arranged at the time when the exposure is made, whereby the numbers of the eggs repro- duced are known, so that certain eggs can be cut out of the plate at any time, rearranged, and photographed. COLOE CHAEACTEB The method of making selections for the color character, and of recording the colors for reference during succeeding generations of the birds, was a difficult one to develop. Various schemes were contemplated and many of these were tried. Schemes of using color tops or wheels, various types of colorimeters, colored photography, and so forth, were considered, but were discarded as being too slow, expensive, or inaccurate. It is very difficult to match the color of an egg with that of any other surface. It was decided that if a system' of matching colors was to be followed, in order to do the work rapidly the eggs must Jbe matched to other eggs of standard colors. ^ By a careful inspection of all eggs produced on the plant for several days, a graduated set of colors containing about fifty tones from chalk- white to dark chocolate brown was obtained. The first seventeen of these tones were the only ones used in the experiment. The contents of these eggs were blown, and the shells were numbered consecutively and Mbmoie 31 Plate VII Plate VII KEY TO COLOR NOTATION USED FOE COLOB STUDIES OF EGGS Color notation number Equivalent in Repertoire de Couleurs • Plate Ton ( Tone ) 1 . ...1 1 2 11 1 3 .. .11 2 4 . 11 3 5 ; 2 .. ..1 6 10 1 7 10 2 8 9 . . 3 9 9 4 10 . . . .312 1 11 . . . .312 2 12 67 1 13 ... .36 1 14 68 1 15 .....68 2 16 68 3 17 68 4 206 Eahl W. Benjamin arranged in a tray. These standard eggs were then carefully matched with their respective colors in Repertoire de Couleurs^ (Plate VII). The color of eggshells is not permanent and will fade considerably if exposed to the Hght for any great length of time. The practice was tried of coating the shells, with various preparations intended to preserve their color, but this was not successful, as all these preparations contained so much color in themselves that the color of the shells thus coated was materially changed. The method finally followed was to use, as standards, eggs with the natural surface. The tray of eggs was kept covered with a black cloth except when in use, and the standard eggs were replaced with others of identical color at intervals varying with the length of time they were used. A clear north light is necessary for accurate color selection, and one must have a trained eye in order to be sure of recording the correct color. The terms chalk^white, .cream-tinted, and brown-tinted are used merely to designate the three groups of colors, in order to show the type of eggs selected for each lot. The color recording was done by one person early in the experiment and by another person laten A trial was made of color recording by several inexperienced persons on the same set of eggs for several succeeding days, and the percentage of error was found to be very sUght. The same standard scale of colors was used thruout the work. The colors were numbered as shown in Plate VII, and these num- bers were used in the correlations and other calculations. METHODS COMMON TO STUDIES OF ALL THE CHABACTERS The chicks used in this study were reared by standard methods, in colony houses with the other experimental chicks on the Cornell experi- mental farm. Previous to 1913 the mature birds were kept in a narrow house divided into nine pens, one pen for each of the nine characters. Under these conditions the one selected male bird for each pen was allowed freedom in the pen. During the 1913 breeding season and after, individual mating coops were installed, and individual mating was followed for the remainder of the experiment. New houses were used for the stock after 1913 (fig. 11). All feeding, trap-nesting, and other details of management » Repertoire de couleurs. Published by La Socifitfi Fransaise des Chryaanth^miBtes and Ren6 Oberthur, with the collaboration of Henri Dauthenay and others. 1905. Study of Selections for Size, SnAPte, and Color of Hens' Eggs 207 were conducted under the supervision of the manager of the Cornell poultry farm and in accordance with the usual practice on that farm. The general plan was to save all the chicks until maturity and then save as many typical specimens from each group as could be satis- factorily housed. Usually about 120 females and 30 males were kept for the study of the three characters, size, shape, and color. When the surplus stock was culled each fall, an effort was made to save the birds Fig. 11. TYPE OF HOUSE USED FOR STOCK AFTER I9I3 representing the extremes of the types. If there were birds that .had produced no chicks during the previous breeding season, these birds were ■usually culled. In cases in which- nearly all the members of a certain family had developed only a medium quality for the character studied, the whole family was often culled to make room for more promising birds. A large proportion of cockerels and pullets were usually saved for the first year, and these were culled fairly closely before being used as breeders during the succeeding years. 208 Earl W. Benjamin These methods of selection explain why so few records are actually available for the study of some of the characters. In following the method of individual mating, each male to be mated with any females in the pen is retained in a coop. Whenever a female is removed from the trap nest, the attendant finds her band number on a posted list and learns the band number of the male with which she is to be mated. Before placing her in the mating coop, however, the work is further checked by looking for the hen number on a tag attached to the coop, and also by comparing the color of her band with the color of the male's band. The female is then placed in the coop and removed at the time of the next inspection of the trap nests. Usually about twelve mating coops were needed in each house. Every egg laid by the mature birds is recorded as to either its size, its shape, or its color, in the same way as the original incubated eggs were recorded. This enables the investigator to compare the character of the egg incubated with the eggs which the resulting pullet produces. Many of the eggs from hens in the size and shape selections were also photographed, as previously explained. , RESULTS The results of the investigation may properly be grouped into those concerned with the inheritance studies and those concerned with other related studies, the former being dealt with first. INHERITANCE STUDIES Variability of production due to differences between the parent types An effort was made to determine to what extent the variabihty of a bird's production was dependent on the differences existing, for the particular character, in the respective dam and sire. The studies made in this regard are illustrated in tables 1 to 12, and a summary is given in table 13. In constructing these tables, the standard deviations for each of the three egg characters considered, for each respective year's production, were calcu- lated, and these were correlated with the differences existing between the means of the respective egg character for all the eggs produced during the life of the respective dam, and as calculated for the respective sire.' 9 The life mean for the sire waa obtained by averaging his respective dam and sire. The character of the egg from which the first sires used in the study were hatched, was taken as the mean for these first sires. When a class is designated by one figure, that figure represents the upper limit of theclass; when a clasb is designated by two figures, the upper figure is included m the class. Study of Selections for Size, Shape, and Color of Hens' Eggs 209 It is clear that no correlation exists for these characters. This state- ment, of course, has reference to the first generation only. This result does not show that when comparing the mean characters for the several offspring from a certain mating, one may not find a variability depending on the difference between the same characters for the respective dam and sire. TABLE 1. Standard Deviation op Egg Size (Weight in Grams) during First Year of Production, Subject; Difference between Egg-Size Life Mean for Dam and for Sire, Eelative ' Coefficient of correlation = .012 ± .052 1.0-1.5 1.6-2.0 2.0-2.5 2.5-3.0 3.0-3.5 3.5-4.0 4.0-4.5 4.5-5.0 5.0-5.5 5.5-6.0 6.0-6.5 6.5-7.0 7.0-7.5 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 1 2 1 2 1 1 1 2 1 1 4 2 2 4 2 1 7 4 2 2 3 11 5 3 2 1 7 2 S 3 3 2 1 4 1 6 S 3 4 1 7 5 2 7 (i 1 1 1 3 2 1 1 1 1 2 1 1 1 1 3 1 1 ' 1 33 53 47 17 3 1 1 1 26 13 10 9 4 13 16 17 13 20 5 10 9 1 1 1 1 169 TABLE 2. Standard Deviation op Egg Size during Second Year of Production, Subject; Difference between Egg-Size Life Mean for Dam and for Sire, Relative Coefficient of correlation = — .28 ± .08 1.5-2.0 2.0-2.5 2.5-3.0 3.0-3.5 3.5-4.0 4.0-4.5 1 2 3 4 5 6 7 8 9»10 11 12 13 14 15 16 17 18 19 \ 1 1 1 2 2 2 1 2 2 1 2 3 ) 2 1 2 2 4 4 2 1 3 2 2 1 2 1 1 1 3 1 4 6 3 3 2 13 27 10 2 2 66 210 Earl W. Benjamin TABLE 3. Standard Deviation of Egg Size during Third Year of Production, Subject; Difference between Egg-Size Life Mean foe Dam and for Sire, Relative Coefficient of correlation = .13 ±.12 1.5-2.0 2.0-2.5 2.5-3.0 3.0-3.5 3.5-4.0 4.0-4,5 4.5-5.0 5.0-5.5 5.5-6.0 1 2 3 4 5 6 7 8 g 10 11 12 13 14 15 16 17 18 19 1 1 1 1 1 1 4 2 1 3 r 1 1 1 1 1 1 2 1 2 1 3 6 4 1 3 13 6 4 1 1 29 TABLE 4. Standard Deviation op Egg Size during Fourth Year op Production Subject; Difference between Egg-Size Life Mean for Dam and for Sire, Relative Coefficient of correlation = — .16 ± .20 2.0-2.5 2.5-3.0 3.0-3.5 3.5-4.0 4.0-4.6 1 2 3 4 5 6 7 8 9 10 11 12 1 1 1 1 1 2 1 1 1 1 3 3 3 2 11 TABLE 5. St4jjdard Deviation of Ego Shape during First Year of Production, Subject; Difference between Egg-Shape Life Mean for Dam and for Sire, Relative Coefficient of correlation = .18 ± .08 1.0-1.5 1.5-2.0 2.0-2.6 2.5-3.0 3.0-3.6 3.5-4.0 4.0-4.5 4.5-5.0 .01 .02 .03 .04 .05 .06 .07 .08 .09 .10 .11 .12 .13 .14 .15 .16 .17 .18 1 T 1 1 1 1 4 3 1 1 1 1 1 1 1 1 4 2 2 ■A 2 1 1 2 2 3 1 1 1 2 1 2 1 2 1 2 1 1 1 2 4 1 1 2 9 6 2 9 S 2 1 4 16 24 11 10 2 70 Study of Selections for Size, Shape, and Color of Hens' Eggs 211 TABLE 6. Standard Deviation op Egg Shape during Second Year op Production, Subject; Dippbrence between Egg-Shape Lipb Mean por Dam and por Sire, Relative Coefficient of correlation = .14 ± .10 0.5-1.0 1.0-1.5 1.5-2.0 2.0-2.S 2.5-3.0 3.0-3.5 3.5-4.0 4.0-4.5 4.5-5.0 5.0-5.5 .01 .02 .03 .04 .05 .06 .07 .08 .09 .10 .11 .12 .13 .14 .15 .16 .17 .18 1 1 1 2 1 1 1 1 1 1 1 2 1 1 1 1 3 1 1 1 1 1 1 '1 1 1 1 1 TABLE 7. Standard Deviation op Egg Shape during Third Year op Production, Subject; Difference between Egg-Shape Life Mean for Dam and for Sire, Relative Coefficient of correlation = .13 ± .18 2.0-2.5 2.5-3.0 3.0-3.5 3.5-4.0 4.0-4.5 4.5-5.0 5.0-5.5 5.5-6.0 6.0-6.5 6.5-7.0 .01 .02 .03 .04 .05 .06 .07 .08 .09 .10 .11 .12 .13 .14 2 1 1 1 1 1 1 1 1 1 1 1 1 3 TABLE 8. Standard Deviation of Egg Shape during Fourth Year of Production, Subject; Difference between Egg-Shape Life Mean for Dam and por Sire, Relative Coefficient of correlation = .45 ± .20 1.5-2.0 2.0-2.5 2.5-3.0 3.0-3.5 3.5-4.0 .01 .02 .03 .04 .05 .06 .07 .08 .09 .10 .11 .12 .13 .14 1 2 1 1 2 1 1 1 1 3 1 3 2 10 212 Eael W. Benjamin HOO^OOOiH m H l\ §a P4 s o « » s is a H° °9 < ■Hcot-Mcqw Ni-HViHl-H MrHfMcO-tfCO (N^i-H ■^Mb-U3iOC0 C* S (N i-i m OS T)< (M CO .-iM o o o i-i iH i-H rH cq « N o) cc m »•«■«*■*■*' 'tji lo lO U3 u3 Study of Selections for Size^ Shape, and Color of Hens' Eggs 213 TABLE 10. Standard Dbviaiion of Egg Coloe dubing Second Yeab of Production, Subject; Difference between Egg-Color Life Mean for Bam and for Sire, Relative Coefficient of correlation = .43 lii .07 0.25-0. SO 0.50-0.75 0.75-1.00 1.00-1.25 1.25-1.50 1.50-1.75 1.75-2.00 2.00-2.25 2.25-2.50 2.50-2.75 2.75-3.00 3.00-3.25 3.2S-3.50 3.50-3.75 3.75-4.00 4.00-4.25 4.25-4.50 4.50-4.75 4.75-5.00 5.00-5.25 5.25-5.50 5.50-5.75 0.5 1.0 1 .5 2 .0 2 .5 3 .0 3 .5 4 .0 4 ,5 5 5.5 6.0 0.5 7.0 7.5 8.0 8.5 9.0 9.5 1 » 3 3 3 2 1 2 1 1 2 1 1 1 2 1 2 1 2 1 1 1 1 1 1 2 1 1 1 2 2 1 3 1 I 1 1 12 15 6 3 6 4 11 1 1 7 10 11 9 5 7 3 4 2 2 2 1 1 1 1 68 TABLE 11. Standard Deviation of Egg Color during Third Year of Production, Subject; Difference between Egg-Color Life Mean for Dam and fob Sire, Relative Coefficient of correlation = .52 ± .13 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 CO 6.6 7.0 7.5 8.0 8.5 9.0 9.5 214 Earl W. Benjamin TABLE 12. Standahd Deviation op Egg Color during Fourth Year of Production, Subject; Difpbrbnce between Egg-Color Life Mean for Dam and for Sibe, Relative CoeflSoient of correlation = .55 ± .15 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 TABLE 13. Summary of Correlations between Standard Deviation of Egg Char- acters DURING Each op the First Four Years of Production, Subject, and Dipperencb between Respective Life Means for Dam and foe Sire, RBLATrvE £electio:i Year of production Coefficient of correlation r Er Number of indi- viduals Size First . .... .012±.052 -.28 ±.08 .13 ±.12 .16 ±.20 0.23 3.50 1.08 0.80 169 Second . . ... 56 Third 29 Fourth '. 11 Shape First .18 ±.08 .14 ±.10 .13 ±.18 .45 ±.20 2.25 1.40 0.72 2.25 70 Second 32 Third 14 Fourth 10 Color First .13 ±.05 .43 ±.07 .52 ±.13 .55 ±.15 2.60 6.14 4.00 3.67 174 Second 68 Third 21 Fourth 10 Study of Selections fob Size, Shape, and Color of Hens' Eggs 215 Inheritance of mean egg type The correlations shown in tables 14 to 22 and summarized in tables 23 and 24 indicate a distinct positive relation between the mean type of either or both parents and the production of the offspring. In table 23 r it IS seen that ^ for the sire ranges from 3 to 18; for the dam, from 4 to 22; and for the average of both parents, from 8 to 39. In table 24 it J- is seen that ^r ranges, for size, from 4 to 10; for shape, from 3 to 8; and for color, from 18 to 39. TABLE 14. Total Avdragb Size (Weight in Grams) op Production of the Off- SPBING, Subject; Size Record for Sire, Relative Coefficient of correlation - .36 ± .04 36 11 38 40 42 4i 40 11 48 3 2 2 1111 1 12 50 4 3 22312 17 Si 2 2 3556111 2 28 51 23 247231 121 5 33 53 2 122 52413 121 6 32 53 1 1 122 11 311 9 23 60 11113 4 11 62 1 112 5 64 113 5 66 11114 68 70 72 74 1 1 13 5 13 3 13 15 24 9 ID 4 1 8 8 5 33 173 216 Eabl W. Benjamin m ^ 3 fn rt n ta P o rn rt" -H a rvi P4 (N P^ 1 a o ■■P H si g s O ta O u; o o -R fl> p ^ d h O 1^ I o H ■^CO NtH j-t^j-iOi ^ (M .Hr- CI Tfi CQ cq 1-1 T-i IN th •-H C^ Tff Cco eooi .-I (NCQCCrH COi-lrtt,-( lO o ^ rt oq !M W PO r-t CO tH M ^Ol (N i-H cq ,-H r-( Study of Selections for Size, Shape, and Color of Hens' Eggs 217 M O fa s O o n ^ t3 ■<* CO 02 O o a ■^ CO g eq OS s -* lO >■ i % II U3 O tA g .2 ^ H to ti a" ^ § § s a 5 o 1 to t^ .s i o s 9 CO £ O »o b C4 U3 O KT »H N lO IH CO s S 5 pq 00 03 «• O o o H U t= fe oa -H S II a O 1^ o 13 O y +s H « q ^ M Ph o b O O 1-1 rH eOCON rHi-i ■ Tit«Ji-lM r-t ^Hi-ICOCONr- T-t .-I.HCO.-I ^H i-H rH Tt* i-H N Study of Selections for Size, Shape, and Color of Hens' Eggs 219 TABLE 18. Total Average Shape of Production of the Offspring, Subject; Shape EecorD fob Dam, Relative Coefficient of correlation = .47 ± .06 54 1 1 56 1 1 58 60 62 64 66 1 1 1 2 1 6 68 2 2 1 5 70 13 12 5 3 1 1 17 72 1 322 72. 13 11 23 74 76 78 80 102000200 12 6 100 187002734 02 76 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 1 1 1 1 1 2 2 2 1 1 1 3 1 2 Fi ■3 1 1 1 3 2 2 7 1 3 1 1 1 1 2 1 1 9, 1 3 1 2 1 1 1 1 1 1 •^ TABLE 19. Total Average Shape op Production op the Offspring, Subject; Average Shape Record for Sire and Dam, Relative Coefficient of correlation = .49 ± .06 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 54 1 1 56 1 1 58 60 62 64 66 1112 1 6 68 112 1 5 70 1 1154311 17 72 1132245311 23 74 12 13 119 76 1 3 13 8 78 - 2 2-4 80 2 2 1000000030"32574 18 13 12 24 1 1 76 220 Earl W. Benjamin TABLE 20. 1.0-1.5 1.5-2.0 2.0-2.5 2.5-3.0 3.0-3.5 3.5-^.0 4.0-4.5 4.5-5.0 5.0-5.5 5.5-6.0 6.0-6.5 6.5-7.0 7.0-7.5 7.5-8.0 8.0-8.5 8.5-9.0 Total Average Color of Production of the Offspring, Subject; Color Record for Sire, Relative Coefficient of correlation = .53 ± .03 . 15 33 38 19 24 12 12 6 3 2 8 26 8 1 216 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 .S 2 3 1 5 5 1 2 2 9 1 fi 5 1 11 2 10 2 1 8 7 8 1 5 2 1 2 2 3 1 1 3 2 6 11 5 7 1 3 1 2 2 1 2 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3 2 1 1 3 4 2 6 3 13 1 2 29 47 12 39 TABLE 21. Total Average Color of Production of the Offspring, Subject; Color Record for Dam, Relative Coefficient of correlation = .67 ± .03 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 1.0-1.5 6 3 9 1.5-2.0 8 2 1 2 2 15 2.0-2.5 5 10 7 3 2 3 1 1 33 2.5-3.0 1 3 7 9 4 2 1 3 4 38 3.0-3.5 2 1 2 4 2 2 2 1 2 1 19 3.5-4.0 4 7 5 2 2 2 24 4.0-4.5 1 6 1 1 1 1 12 4.5-5.0 1 1 3 2 2 1 1 12 5.0-5.5 1 1 1 1 2 6 5,5-6.0 1 1 3 6.0-6.5 1 1 2 6.5-7.0 1 1 4 2 g 7.0-7.5 1 8 11 5 26 7.5-8.0 1 1 1 2 1 2 8 8.0-8.5 8.5-9.0 1 1 3 11 42 43 18 12 11 11 13 14 14 14 9 216 Study of Selections for Size, Shape, and Color of Hens' Eggs 221 TABLE 22. Totai, Avebaob Colob of Productton of the Offspbino, Subject; Avebagb CoLOB Recobd fob Sibe and. Dam, Rblativb 2.5 CoefiScient of correlation = .79 d= .02 3.0 3.5 4.0 4.S S.O 5.5 6.0 6.5 7.0 1.0-1.5 3 2 1 2 1 g 1.5-2.0 3 4 1 2 4 1 15 2.0-2.5 7 2 7 1 10 4 1 1 33 2.5-3.0 6 2 6 8 13 2 1 ,W 3.0-3.5 1 3 2 7 3 1 2 II 3.5-4.0 3 3 11 7 94 4.0-4.5 1 1 4 4 2 1?! 4.5-5.0 4 5 1 1 1 1? 5.0-5.5 2 3 1 6 5.5-6.0 ~ 1 1 1 3 6.0-6.5 1 1 9, 6.5-7.0 1 3 1 3 8 7.0-7.5^ 1 1 2 5 17 ?.f> 7.5-8.0 1 2 2 2 1 8 8.0-8.5 8.5-9.0 1 1 22 18 49 10 12 21 216 TABLE 23. Sitmiiabt of Corbelations between Total Avebagb Chabaoters of Production of the Offspring, Subject, and Average Characters of Parents, Relative ' '. Correlated parentage Character studied CoeflBcient of correlation r Er Number of indi- viduals Sire Size .36±.04 .21±.07 .53±.03 9 3 18 173 76 Color 216 Dam Size .22±.05 .47±.06 .67±.03 4 8 22 173 Shape 76 Color 216 Size .42±.04 .49±.06 .79±,02 10 8 39 173 Shape 76 Co?or 216 222 Eabl W. Benjamin TABLE 24. Summabt Given in Table 23 Arranged Accordinq to Characters Character Correlated parentage Coefficient of correlation r Er Number of indi- viduals Size Sire .36±.04 .22±.05 .42±.04 9 4 10 173 173 Sire and dam 173 Shape Sire .21±.07 .47±.06 .49±.06 3 8 8 76 Dam ' 76 Sire and dam ... 76 Color .53±.03 .67±.03 .79±.02 18 22 39 216 Dam ' 216 Sire and d;^m . -^ 216 All of these correlations are significant, especially since they arise from a random population. From the results of this study, it would appear that the quahty of either the male or the female parent will affect the type of egg to be produced by the offspring, with the female having sUghtly greater influence-. A certain character is of much greater influence if possessed by both individuals than if possessed by either one alone. This does not agree with some results obtained by Pearl (1912, and 1915 a and b) in dealing with quantity of production, and it does not show quite the conditions found by Goodale (1918), who also worked with the quantity factor; it does agree fairly closely, however, with the general opinion prevaihng among poultrymen. The results for the whole experiment relative to the mean character of the progeny in relation to the respective characters of the sire and the dam, are charted in figures 12 to 17. References to large, small, round, long, brown, or white parents or progeny relate to the quality of the eggs produced by those birds, not to the size, shape, or color of the birds. The terms large and small refer, respectively, to means of the sizes of eggs produced during the birds' lifetime, of 56 grams or more, and of less than 56 grams; the terms round and long refer to means of the index figures of the eggs produced during the birds' lifetime, of 72 or more, and of less than 72, respectively; and the terms brown and white refer to means of the color of eggs produced during the birds' lifetime, of 3 or higher, Stodt of Selections for Size, Shape, and Color of Hens' Eggs 223 and of lower than 3, respectively. The exact means for the various groups shown in figures 12 to 14 are given in table 25: TABLE 25. Mean Chabactebs of Bibds Available fob Use in Calculatino Data FOB FiGUBES 12 TO 14 Character type Mating Mean character for sire Mean character for dam Mean character for progeny Size Large sire and, small dam Small sire and large dam 59.6 51.7 60.3 51.7 51.5 60.6 59.6 51.7 54.3 53.9 57.2 Small sire and small dam 51.6 Shape 73.0 67.0 73.0 65.4 69.3 75.4 '■ 76.0 69.1 71.5 Lons sire and round dam. . 72.5 RiOUiid sire a.ii(l rouud dam 75.0 71.0 Color Brown sire and white da.m 4.81 2.11 4.56 2.34 2.34 4.78 4.55 2.19 3.00 3.27 Brown sire and' brown dam 3.75 2.60 Weight (grams) large Small Frog- BJre dam eny (25) (49) Small large Frog' sire dam eny (18) (81) Large Large Frog- dam eny (23) '(41) Small Small Frog> ore dam .(17) (39) Pig. 12. mean size characters of sires, dams, and progeny in all matings The figures in parentliesis designate the numbers of birds available for the respective calculations 224 Eakl W. Benjamin Pig. Long Bound Prog- Round Round Prog- Long Long Prog- sire dam eny siie dajn eny sire, dam eny (10) (26) fl) (2) (16) (46) 13. MEAN SHAPE CHARACTERS OF SIRES, DAMS, AND PROGENY IN ALL MATINGS The figures in parenthesis designate the numbers of birds available for the respective calculations ' Round Long Frog- sire dam eny (3) (9) Color Brown White Prog- sire dam eny (27) (70) Wliite Brown Prog- sire dam eny (12) (30) Brown Prown Prog- sire dam eny (33) (70) Wliite Wliite Prog- sire dam eny (27) (29) Fig. 14. MEAN COLOR CHARACTERS OF SIRES, DAMS, AND PROGENY IN ALL MATINGS The figures in parenthesis designate the numbers of birds available for the respective calculations It is seen in figures 12 to 14 that in every instance in which one extreme character has been mated with another, the progeny have dis- Study of Selections foh Size, Shape, and Color of Hens' Eggs 225 played a character between the two. In most instances in which the sire and the dam were both of the same extreme character, the progeny dis- played a cliaracter nearer to normal than either of the parents. In the case of small size, however, this tendency was reversed, and the character for the progeny from two small parents was of a still smaller type. In this case it is probable that the effect of the size of body was to limit the size of the eggs (Benjamin, 1914). The relative effect of the sire and the dam is shown clearly in figm'es 15 to 17. In figure 15 it is seen that small size is predominant over large size. The sire will transmit small size to the progeny much more strongly than large size. In the instance in which both parents are large, only 58.6 per cent of the progeny possess the "large" character; but when Small sire large mre Small si'e Large dam Large dam Small dam Fig. 15. relation of progeny size characters to sire and dam The white area in each case designates the proportion of progeny showing the same character as that of ^ the sire both parents are small, 81.9 per cent of the progeny possess the "small" character. The two parents appear here to have about equally strong influence in transmitting the "small" character. The predominance of the small size may be due to the additional physiological factors involved by the size of the dam's body restricting the size of egg which can possibly be produced, without regard to any inherited tendencies. A hen with a large body can produce a small egg, but a hen with a small body cannot so readily produce a large egg. The question of the inheritance of egg shape may not be entirely free from the physiological compUcations involved in the study of egg size. This opinion is borne out by figure 16. The dam seems to have nearly 60 per cent of the influence on the progeny. The fact that the two long parents have a somewhat higher percentage of the progeny following their type than do the two round parents, would lead to the theory that 226 Earl W. Benjamin the length character is somewhat predominant over the width; other- wise one would expect to find more than 50 per cent of round progeny when both sire and dam are round. Both the size and the shape of the egg seem to be about equally trans- mitted to the progeny by the dams and by the sires. These two factors Long eire Hound dam Round sire Round dam Long sire Long dam Fig. 16. relation of progeny shape characters to sire and dam The white area in each case designates the proportion of progeny showing the same character as that of the sire appear, however, to be independent, as is shown by an entire lack of correlation between them (Benjamin, 1912). Such a condition as is found here is the reverse of what might be expected if the results obtained by other workers (Pearl and Curtis, 1916) on Barred Plymouth Rocks were borne out with the strain of White Leghorns used in these experi- 4r) \ 76.5%} White sire White dam Fig. 17. relation of progeny color characters to sire and dam The white area in each case designates the proportion of progeny showing the same character as that of the sire ments. Pearl and Curtis found the index figure and the weight of eggs to be negatively correlated. The study of the color inheritance (fig. 17) shows about equal influences of sire and dam. When both parents are of the "white" character, they seem to be able to transmit their character more definitely than when Study of Selections for Size, Shape, and Color of Hens' Eggs 227 both are of the "brown" character, but this difference is not great. Neither color and neither parent seem to have a predominance. These results are an accumulation of data from six different years, with all the variations in conditions that must always occur. Hence the facts shown can apparently be accepted as giving undoubted evidence of the inheritance of the characters in question. Relation of egg incubated to mean egg type of bird hatched The correlations shown in tables 26 to 49, and sunamarized in tables 50 and 51, show a general relationship between the particular type of egg incubated and the type of egg produced by the chick hatched, both for the separate years of the bird's production and for its life mean." ^^r is much less significant for these studies than for the studies of the relation existing between the mean productions of parents and progeny. Apparently the particular type of egg incubated has some effect on the type of egg which the offspring will produce, but not so much effect as the mean production of the hen which laid that incubated egg. In this study the coefficient of correlation for the size character, as shown in table 50, is of greater significance than that for the other char- acters, as is the case in all of the work here reported. The shape character shows a fair degree of correlation. The color character exhibits a peculiar condition. The correlations with the pullets' eggs incubated, for the first and second years, are insignifi- cant; the third-year correlation is based on too few individuals to be of much value; and the life-mean correlation shows a distinct negative coefficient. This condition is probably due to the great irregularity that exists in the coloration of successive eggs laid by most individuals. Sufficient proof is not at hand to warrant the conclusion that a negative correlation actually exists for this character, but it is believed that such a negative or insignificant correlation may be expected, due to the irregu- larity of the material. ii^The termapuUet and hen, as used in' this memoir, refer to female birds during their first season of production and during their later seasons of production, respectively. 228 Eabl W. Benjamin TABLE 26. Mean Size (Weight in Grams) op Fiest Year's Production of Birds, Subject; Size of Pullets' Eggs thom Which Respective Birds Were Hatched, Relative Coefficient of correlation = .40 ± .063 46 48 50 52 54 56 58 60 62 64 45 47 49 51 53 55 57 59 61 63 65 1 1 2 2 2 2 1 1 5 2 1 1 1 1 1 1 1 4 5 1 3 2 1 1 1 3 2 3 4 3 1 2 1 1 4 1 1 2 1 1 1 1 1 1 2 1 13 6 20 10 11 n 11 11 17 12 4 3 1 1 81 TABLE 27. Mean Size of Second Year's Production of Birds, Subject; Size of Pul- lets' Eggs from Which Respectivb Birds Were Hatched, Relative Coefficient of correlation = .37 ± .103 47 49 51 53 65 57 59 61 50 1 1 2 52 1 1 54 1 1 2 1 5 66 1 3 1 1 7 58 1 2 1 1 6 60 1 2 1 1 6 62 64 1 1 1 2 3 66 68 70 1 1 33 Study of Selections for Size, Shape, and Color of Hens* Eggs 22^ TABLE 28. Mean Size of Third Ybab's Pboduction op Birds, Subject; Size op Pul- lets' Eggs from Which Respective Birds Were Hatched, Relative Coefficient of correlation = .30 ± .131 47 49 51 53 55 57 59 61 60 1 1 52 1 1 1 3 54 1 2 1 5 56 1 1 1 3 58 2 2 4 60 1 2 3 62 1 ' 1 64 1 1 66 68 70 72 74 1 1 22 TABLE 29. Mean Size of Fourth Year's Production op Birds, Subject; Size of Pul- lets' Eggs prom Which Respective Birds Were Hatched, Relative Coefficient of correlation = .50 ± .191 50 52 54 56 58 60 62 64 66 47 49 51 53 55 57 59 1 1 1 1 1 1 1 2 1 ^30 Eabl W. Benjamin TABLE 30. Mean Size op Life Production or Bibds, Subject; Size of Pullets' Eggs FBOM Which Respective Bibds Webb Hatched, Rblatite Coefficient of correlation = .37 ± .065 45 47 49 51 53 55 57 59 61 63 65 46 1 1 48 1 1 2 2 2 8 50 1 1 3 1 1 1 8 62 1 2 1 3 1 1 9 54 2 1 7 3 1 1 15 56 2 2 2 1 3 3 1 1 15 58 1 2 4 3 1 2 13 60 1 1 1 1 1 1 6 62 2 2 64 1 1 1 3 68 ,0 68 70 72 74 1 1 13 6 20 10 10 81 TABLE 31. Mean Size op First Year's Production of Birds, Subject; Size op Hens' Egos from Which Respective Birds Webs Hatched, Relativi: Coefficient of correlation = .31 ± .065 36 38 40 42 44 46 48 SO 52 54 56 58 60 62 64 45 47 49 51 53 55 57 59 61 63 65 67 69 1 1 1 1 3 1 2 1 1 1 3 f 3 2 3 2 5 1 1 2 3 2 1 4 2 2 1 1 2 1 2 1 1 2 3 1 2 1 2 2 1 1 4 1 1 2 1 1 1 1 1 1 1 2 2 13 11- 17 12 1 1 2 4 8 17 20 15 9 5 1 4 1 88 Study op Seeections fob Size, Shape, and Color of Hens' Eggs 231 TABLE 32. Mean Size of Second Year's Production op Birds, Subject; Size op Hens' £qos from Which Respective Birds Were Hatched, Relative Coefficient of correlation = .46 ± .099 50 1 1 2 1 5 52 1 1 2 54 1 1 2 56 11 13 58 2 12 1 6 60 1 1 13 62 1 1 64 1 3 4 66 68 112 70 1 1 221545201421 29 TABLE 33. Mean Size op Third Year's Production op Birds, Subject; Size op Hens' Eggs from Which Respective Birds Were Hatched, Reiativb Coefficient of correlation = .65 ± .123 •45 47 49 61 53 55 57 69 61 63 66 52 54 56 58 60 62 64 66 2 1 1 2 1 1 2 1 1 1 1 10 232 Eael W. Benjamin TABLE 34. Mean Size op Life Production of Birds, Subject; Size op Hens' Eggs PROM Which Respective Birds Were Hatched, Relati-vb Coefficient of correlation = .34 ± .063 45 47 49 51 53 55 57 59 61 63 65 67 69 71 73 75 36 1' 1 38 40 42 44 ,0 46 1 1 48 2 2 4 50 1 2 3 4 10 52 112 3 3 5 11 17 54 113 14 2 1 12 16 56 141241 111 16 68 1 13 1 11 8 60 12 111 6 62 1112 5 64 66 2 111 16 2 3 5 11 11 9 16 14 3 5 3 3 4 1 90 TABLE 35. Mean Shape op First Year's Production op Birds, Subject; Shape op Pullets' Eggs prom Which Respective Birds Were Hatched, Relative Coefficient of correlition= .39 ± .106 64 1 1 63 1 1 2 68 1 1 1 3 70 1 12 4 72 2 3 2 12 10 74 1 2 1116 76 1 1 78 1 1 80 1^1 13124352 2 4 1 129 Study of Selections foe Size, Shape, and Colob of Hens' Eggs 233 TABLE 36. Mean Shape op Second Yeab's Production op Birds, Subject; Shape op Pullets' Eggs from Which Respective Birds Were Hatched, Relative CoeS&cient of correlatiou = .23 ± .192 68 70 72 74 76 69 70 71 72 73 74 75 76 77 1 1 1 1 1 1 1 1 1 1 1 4 4 2 1 11 TABLE 37. Mean Shape of Life Production op Birds, Subject; Shape op Pullets' Eggs from Which Respective Birds Were Hatched, Relative Coefficient of correlation = .43 ± .102 66 68 70 72 74 76 78 80 68 69 70 71 72 73 74 75 76 77 78 79 80 1 1 2 1 1 1 1 3 1 2 1 1 1 1 2 1 1 1 1 3 1 6 10 6 1 1 1 29 234 Eakl W. Benjamin TABLE 38. Mean Shape of First Yeab'b Production op Bieds, Subject; Shape op Hens' Eqqs from Which Respective Birds Were Hatched, Relative Coefficient of correlation = .34 ± .083 61 62 63 64 65 63 67 68 69 70 71 72 73 74 75 76 77 77+ 54 56 58 60 62 64 66 68 70 72 74 76 78 80 1 1 1 1 I 2 1 , 5 1 1 1 ' 1 2 1 7 1 1 1 1 2 6 1 2. 1 3 2 1 2 2, 17 1 1 1 2 1 2 2 1 1 • 1 1 1 1 8 4 3 1 1 1 0323346737451 62 TABLE 39. Mean Shape of Second Year's Production op Birds, Subject; Shape op Hens' Egos from Which Respective Birds Were Hatched, Relative 66 68 70 72 74 76 78 67 - 68 69 70 71 72 73 74 75 76 77 1 1 1 1 1 1 1 1 1 1 2 1 2 1 1 1 2 1 1 1 1 1 1 1 4 1 5 6 6 4 1 27 Study of Selections for Size, Shape, and Colok op Hens' Eggs 235 TABLE 40. Mean Shape of Third Year's Production of Birds, Subject; Shape of Hens' Eggs from Which Respective Birds Were Hatched, Relative Coefficient of correlation = .52± .142 54 56 58 60 62 64 66 68 70 72 74 69 70 71 72 73 74 75 76 77 1 1 . 1 1 1 1 1 1 1 1 1 1 2 1 1 1 1 1 4 2 3 12 TABLE 41. Mean Shape of Life Production of Birds, Subject; Shape op Hens' Eggs FROM Which Respective Birds Were Hatched, Relative . Coefficient of correlation = .31 ± .084 61 or 54 56 58 60 62 64 66 68 70 72 74 76 78 less 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 77+ 1 1 I 1 1 1 1 1 1 1 1 1 1 1 2 2 3 1 1 1 1 1 2 1 1 2 1 1 3 1 1 1 1 1 2 2 1 3 1 1 1 110 1 03 "2 334673746 e 1 1 5 3 12 16 6 5 3 1 53 236 Eabl W. Benjamin TABLE 42. Mean Color of First Year's Production of Birds, Subject; Color op Pullets' Eggs from Which Respective Birds Were Hatched, Relative Coefficient of correlation = — .12 ± .07 6 1.0-1.5 1 2 3 1 1.5-2.0 1 7 3 2 1 2.0-2.5 7 8 3 2.5-3.0 4 12 2 4 1 3.0-3.5 6 3 1 3 1 3.5^.0 1 1 1 4.0-4.5 1 1 2 4.5-5.0 3 3 1 1 5.0-5.5 1 2 5.5-6.0 2 2 6.0-6.5 6.5-7.0 , 7.0-7.5 1 1 28 38 20 10 7 14 18 23 14 3 4 8 3 4 2 1 100 TABLE 43. Mean Color of Second Year's Production op Birds, Subject; Color of Pullets' Egos prom Which Respective Birds Were Hatched, Relativp Coefficient of correlation = .002 ± .105 1 6 1.0- 1.5 1 1.5- 2.0 1 2 2.0- 2.5 1 4 2.5- 3.0 2 2 1 1 3.0- 3.5 3 2 1 1 3,5-4.0 2 1 4.0- 4.5 3 1 1 4.5- 5.0 1 5.0- 5.5 2 1 5.5- 6.0 6.0- 6.5 1 2 6.5- 7.0 1 7.0- 7.5 1 7.5- 8.0 8.0- 8.5 8.5- 9.0 9,0- 9,5 9,5-10,0 10.0-10,5 1 13 16 3 1 3 5 7 7 3 5 1 3 3 1 1 1 41 Study of Selections fob Size, Shape, and Color of Hens' -Eggs 237 TABLE 44. Mean Color of TmRD Year's Production op Biros, Subject; Color op Pullets' Eqqs prom Which Respective Birds were Hatched, Relative Coefficient of correlation = .57 ± .15 12 3 4 1.5-2.0 1 ' 1 2,0-2.5 2.5-3.0 2 2 3.0-3.5 1 1 2 3.5-4.0 1 1 2 4.^4.5 1 1 4.5-5.0 5.0-5.5 5.5-6.0 1 1 TABLE 45. Mean Color op Lipb Production op Birds, Subject; Color op Pullets Eqqs from Which Respective Birds Were Hatched, Relative Coefficient of correlation = — .26 ± .1)6 12 3 4 5 6 7 1.0-1.5 1 2 2 5 1.5-2.0 1 6 2 2 11 2.0-2.5 5 6 3 1 15 2.5-3,0 5 11 2 5 1 24 3.0-3.5 5 4 1 2 1 13 3.5^.0 2 4 3 9 4.0-4.5 1 1 2 1 5 4.5-5.0 3 3 1 1 8 5.0-5.5 2 2 4 5.5-6.0 2 1 3 6.0-6.5 6.5-7.0 7.0-7.5 1 1 2 7.6-8.0 1 1 28 38 20 8 4 1 1 100 238 Earl W. Benjamin TABLE 46. Mean Color or First Year's Production op Birdb, Subject; Color of Hens' Eggs from Which Respective Birds Were Hatched, Relative Coefficient of correlation = .20 ± .08 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 1.0-1.5 1.6-2.0 2.0-2.5 2.5-3.0 ;.0-3.5 .5-4.0 .0^.5 .5-5.0 1.0^.5 .5-6.0 6.0-6.5 6.5-7.0 7.0-7.5 7.5-8.0 8.0-8.5 8.5-9.0 1 2 2 4 1 1 3 3 2 1 5 3 3 3 2 1 2 1 1 1 1 3 2 1 1 1 2 2 1 1 1 2 1 1 1 1 1 1 15 15 17 9 4 400000000100001 1 9 10 16 7 6 7 2 4 1 1 1 1 66 TABLE 47. Mean Color of Second Year's Production of Birds, Subject; Color op Hens' EoGS from Which Respective Birds Were Hatched, Relativb Coefficient of correlation = .31 zt .10 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 1.0-1.5 1 1.5-2.0 1 1 2.0-2.5 1 2 3 1 - 1 2.5-3.0 1 3.0-3.5 2 1 3.5H1.0 2 4.0-4.5 1 1 4.5-5.0 1 1 1 1 6.0-5.5 1 1 5.5-6.0 1 6.0-6.5 6.5-7.0 1 7.0-7.6 7.5-8.0 8.0-8.6 8.5-9.0 1 54842300000 10 1 Study op Sblections fob Size, Shape, and Color of Hens' Eggs 239 TABLE 48. Mean Color of Third Year's Production of Birds, Substect; Color of Hens' Eggs from Which Respective Birds Were Hatched, Relative Coefficient of correlation = .17 ± .20 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 1 1 1 1 1 3 1 1 1 11 1.0-1.5 1 * 1.5-2.0 1 2.0-2.5 1 2.5-3.0 1 3.0-3.5 3.5-4.0 1 4.0-4.5 1 1 1 4.5-5.0 1 5.0-5.5 1 5.5-6.0 6,0-6.5 6.5-7.0 7.0-7.5 1 1141110000000 1 01 TABLE 49. Mean Color of Life Production op Birds, Subject; Color of Hens' Eggs FROM Which Respective Birds Were Hatched, Relative Coefficient of correlation = .28 ± .08 12 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 1.0-1.5 1.5-2.0 2.0-2.5 2.5-3.0 3.0-3.5 .5-4.0 .0-4.5 .5-5.0 .0-5.5 .5-6.0 6.0-6.5 6.5-7.0 7.0-7.5 7.5-8.0 8.0-8.5 8.5-9.0 1 1 1 3 1 2 4 4 1 > 5 3 3 2 2 1 2 2 2 3 2 1 1 1 1 2 2 1 1 1 1 3 2 1 1 1 1 1 15 15 18 9440000000 1 01 1 6 11 15 7 7 7 5 3 2 0- 2 1 67 240 Eakl W. Benjamin TABLE 50. SuMMABT of Cokeelations between Chaeactek-Meanb roH Peoduction FOR Separate Years and for Life, Subject, and Chaeactees foe Paebnt Egos iNCiraATED FROM PuLLETS OE FROM HeNS, RELATIVE Character Year of production (means for) Pullets' eggs incubated Hens' eggs incubated Coefficient of correlation r Er Number of indi- viduals Coefficient of correlation r Er Number of indi- viduals Size First .40 ±.083 .37 ±.103 .30 ±.131 .50 ±.191 .37 ±.065 •6.3 3.6 2.3 2.6 5.7 81 33 22 7 81 .31±.065 .46±.099 .65±.123 4.8 4.6 5.3 88 29 Third 10 Fourth.. . Life . .34±.063 90 Shape First .39 ±.103 .23 ±.192 3.7 , 1.2 29 11 " "29 .34±.083 .47±.101 .52±.142 .31±..084 4.1 4.7 3.7 3.7 62 Second 27 Third 12 Life.... .43 ±.102 4.2 53 Color First -.12 ±.07 .002±.105 .57 ±.15 -.26 ±.05 1.7 0.02 3,8 4.3 100 41 9 100 .20±.08 .31±.10 .17±r20 .28±.08 2.5 3.1 0.8 3.5 66 28 Third 11 Life 67 TABLE 51. Summary of -=- from Table 60 Er Year of production Character ^ r Er Pullets' eggs incubated Hens' eggs incubated First Size 6.3 4 8 Shape 4 1 Color 2 5 Second Size 3.6 1.2 0.02 4 6 Shape 4 7 Color 3.1 Third Size 2.3 5 3 Shape Color 3 7 3.8 8 Life Size 5.7 4.2 4.3 5 4 Shape 3 7 Color 3 5 Study of Selections for Size, Shape, and Color of Hens' Eggs 241 The summary in table 51 groups the figures for the factor of significance, pT' according to years and life means. There is a more significant cor- relation between the life mean of the offspring production and the type of parent egg incubated, than between the production of any of the separate years and the incubated egg. This means that the egg incubated affects the mean type of egg produced during the whole hf e of the bird hatched, to a greater extent than it affects the pullet-year production or the pro- duction of any other single year. There is a strong correlation, as shown in tables 52 to 54, when a study is made of the relationship between the individual eggs incubated and all TABLE 52. ^ Size (WEiaHT in Grams) or Eggs Laid by Birds, Subject; Size op Eggs from Which Rbbpective Birds Were Hatched, Relative Coefficient of correlation = .458 ± .007 46 48 50 52 54 56 58 60 62 64 66 68 70 72 74 1 1 1 4 12 10 22 53 167 302 498 614 735 786 694 486 320 274 169 57 22 14 5 3 5,250 2S-30 1 30-32 1 32-34 1 34-36 3 1 36-38 4 6 2 38-40 3 6 1 40^2 2 8 1 5 1 5 42-44 10 8 3 27 2 2 1 44-46 41 32 11 63 3 3 9 5 46-48 68 45 23 82 28 12 30 3 11 48-50 77 108 32 89 32 30 76 4 5 44 1 50-52 45 155 39 41 45 70 124 8 11 76 52-54 26 129 65 29 79 98 110 29 25 137 8 54-56 15 69 79 25 143 120 91 51 27 153 12 1 66-58 3 42 45 24 129 87 65 1 104 35 157 1 1 58-60 1 24 28 17 75 50 59 74 59 94 4 1 60-62 6 33 13 28 36 38 1 38 46 79 2 62-64 1 6 10 2 15 28 35 30 116 31 64-66 6 1 5 17 22 17 85 16 66-68 1 4 1 49 1 1 68-70 1 1 1 19 70-72 1 13 72-74 1 1 3 74-76 2 1 300 646 376 418 585 557 667 2 356 500 811 28 the individual eggs produced by the respective birds hatched. The factor g- equals, for size, shape, and color, respectively, 65, 20, and . 16. This is significant ^nd suggests the same relative degrees of inheritance as are found in other studies in this investigation. 242 Eabl W. Benjamin The comparable coefficients of variability, calculated on the basis of unit classes, for the eggs used in compiling tables 52 to 54 are: for size (table 52), 20 per cent; for shape (table 53), 10 per cent; for color (table 54), 74 per cent. The greater irregularity in the color of eggs as compared TABLE 53. 54- 56 56- 58 58- 60 60- 62 62- 64 64^ 66 66- 68 68- 70 70- 72 72- 74 74- 76 76- 78 78- 80 80- 82 82- 84 84- 86 86- 88 88- 90 90- 92 92- 94 94- 96 96- 98 98-100 Shape of Eqgs Laid bt Bibds, Subject; Shape op Eggs prom Which Respective Bibds Webe Hatched, Relative 64 Coefficient of correlation = .204 ± .01 66 68 70 72 74 76 78 80 1 1 1 6 1 3 2 2 2 21 1 7 7 8 65 . 6 24 16 16 146 17 71 58 34 132 38 222 152 80 1 143 44 310 193 146 97 80 397 175 211 39 43 355 122 148 21 13 175 59 29 5 4 48 4 10 1 9 3 4 1 9 3 1 1 1 1 1 2 1 1 1 2 14 46 127 326 624 840 961 707 307 71 17 11 3 1 2 1 2 2 247 1,637 796 701 1 4,065 with the other characters undoubtedly accounts for the results in this one correlation with the pullets' eggs incubated. The coefficients of correlation for the study of the mean production with the hens' eggs are positive for all characters and years. The color correlation is about as significant as the shape correlation. Study op Selections for Size, Shape, and Color of Hens' Eggs 243 TABLE 54. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 CoiiOB OF Egos Laid bt Bibds, StJBJBCT; Color of Eaos fbom Which Rbspeciive Bibds Webe Hatched, Relative Coefficient of correlation = .145 ± .009 12345678 938 '1;405 1,101 686 389 235 119 130 83 86 91 37 39 23 3 1 1 5,367 143 238 40 182 175 117 10 33 396 298 168 188 206 107 -26 1-6 • 215 174 173 183 227 56 42 31 68 119 137 110 173 32 33 14 27 71 62 85 86 24 12 22 15 44 47 47 41 8 12 21 7 18 28 31 21 7 1 6 12 14 26 44 17 2 1 14 5 18 15 26 2 16 5 26 20 19 3 2 7 2 21 19 30 7 i 8 19 5 10 2 6 1 8 16 9 11 6 2 2 1 2 1 1 892 995 791 938 1,050 367 144 190 HnuM ~_^ December January February March Pig. 18. variation of size (weight in grams) of successive eggs laid during early pullet production The squares blocked in black indicate the days on which eggs were laid by the respective pullets 244 Eael W. Benjamin Relaiion of eggs incvbated to types of eggs produced by the respective birds hatched Some further features of the relationship existing between the types of eggs incubated and the egg types produced by the respective birds hatched, are shown in figures 18 to 25. These figures represent only a small part of the available material resulting from the study, and are used here merely to show typical conditions. Gmms [3 U 16 21 26 31 36 41 46 51 S6 61 66 71 76 81 86 .91 96 101 Fig. 19. variation of sizb (weight in grams), by weekly averages, of eggs pro- duced BT dam for two years AND BY PROGENY DURING EARLY PULLET PRODUCTION The heavy horizontal line in each division represents the character of the parent egg incubated; the heavy curve represents the production of the chick hatched; the light curve represents the production of the progeny of the chick. The dotted lines indicate that no eggs were produced during the periods which they cover Pullets 8882F and 8939F, illustrated in figure 18, are from small eggs, but pullet 8872F is from a large egg. It is evident that the tendency is for a pullet to produce eggs of the same size as the egg from which she was hatched. Sometimes small eggs are obtained from hens that Study of Selections for Size, Shape, and Color of Hens' Eggs 245 Fig. 20. shadow photographic record of relation between size of egg incubated and size of eggs produced by the resultant chick Each row of progeny production shows twelve eggs, which were selected at regular intervals during the respective year's production. All eggs were photographed each year, but only twelve eggs for each year could be represented in this group 246 Eakl W. Benjamin ordinarily lay large eggs, and vice versa; this probably accounts for the low correlation in studies of mixed flocks, while the study of separate matings shows more definite results. The heavy curve for line 3916F in figure 19 represents the record for the bird whose early pullet daily record is shown as 8882F in figure 18. The photographic record, figure 20, shows the relative sizes of eggs produced by hne 8224F, one of the largest lines, and by line 3916F, one of the smallest hues. The difficulty of observing the fine differences in size, except by careful measurements, is seen from this figure. Under line 3916F^ shown another record of the production of 8882F. January February March * April Pig. 21. variation of shape of successive eggs laid during early pullet production The squares blocked in black indicate the days on which eggs were laid by the respective pullets In figures 21 and 22 are shown the daily and weekly fluctuations of shape. A photographic record of two of the first-year inheritance results for the shape character is shown in figure 23. Both of the fines shown in figure 23 are shown also in figure 22. Neither the shape nor the size of Study op Selections for Size, Shape, and Color of Hens' Eggs 247 eggs has a large coeflScieiit of variability, and this fact is reflected in the curves and in the photographic record. Shape index TTTTI 95 85 :::;;::::;:::;:::::;:;;:;::;;;::; ;;;; :;;:;;;;: ;;; ;:::; i; 1 75 ::■ i\': :'■''■'' ■': :' -J ;;; |::::^, ::s .;:,; ,:!l m f \\ 'ir' 65 :::: t::; :::: :::::::::: ::: ::::: ::: !:■■ .:'.', . a \%t\ :'.:: ::::^::::::: :::::::::: ::: ::::: :::: ::::::::: :: ::::: :::: 95 ' ?' ". "' "' '''. '■'- '-"'. ,,, ■ ■ 8ii 75 :j ;:;::;::::::;;:::: 65 '' ::. ::„:|iiiiiii| jil iiil III liiil liiii liiii | 1 1 !!!! !!! 1 j Ml 105 95 85 |b: T + f : f 1:+-- -j;-^- t - fe:: V Vt) ill 1 11 tii it! 65 1* tt-t- i ; ';: ::; :: iL. mjji Weeks 11 " 16 21 26 ' 31 36 41 46 51 56 61 66 .71 76 81 86 91 96 101 Fig. 22. variation of shape, by weekly averages, of eggs produced by dam for two years and bt progeny during early pullet production The heavy horizontal line in each division represents the character of the parent egg incubated; the heavy curve represents the production of the chick hatched; the light curve represents the productijn of the progeny of the chick. The dotted lines indicate that no eggs were produced during the periods which they cover The color character has a much higher coeflBcient of variabiKty, as may be observed from figures 24 and 25. The pullets included in figure 24 were all of the brown-egg type, but in figure 25 both brown-egg and white- egg types are shown. In these figures there seems to be a tendency for the type of egg produced by the original pullet hatched, and her later offspring, to resemble the original egg incubated. The writer can explain the negative or practically zero correlation for the color character in the 248 Eael W. Benjamin Pig. 23. shadow photographic record of relation between shape of egg incu- bated AND shape of eggs PRODUCED BY THE RESULTANT CHICK Each row of progeny production shows twelve eggs, which were selected at regular intervals during the respective year's production. All eggs were photographed each year, bat only twelve eggs for each year could be represented in this group Study of Selections foe Size, Shape, and Color of Hens' Eggs 249 data previously reviewed, only by the high coefficient of variabihty and the probabihty that many abnormal eggs are incubated instead of the normal type for the respective dam. Color . 16- . 1 1 ' ■ ■ : : . 1 1 1 , 1. 1 1 ! 1 IS- . 3 I \\,ii.^.jyM^^J^if,.^^ |/>^V^\^/V\, 1 15- I. 6- — »*■ ^J— lUEM^j Y -If. 1- 1 ; : 20 24 28 1 5 9 18 17 21 25 39 2 10 14 IS 26 1 5 9 IS 17 21 December March 29 2 April jBnuary February Pig. 24. variation of color of successive eggs laid during early pullet production The squares blocked in black indicate the days on which eggs were laid by the respective pullets 250 Eakl W. Benjamin Color 16 ::::;::;:;;;;;:::::;;;;;::::r;;;;;:;;;::::i:::i::;: mil illlilill ■■■■■ ■■ ■■■■■■■ :-::-;i;::i:i::-]ii"b{^j::f J:-;'"!;;:::;:::::]- lllllliHIIIIIHIilllllll mil III ■■■■■■ 11 ssusii v.:v. :s:sii Q -:: fctHtt, ii :i J is ■■■■■B ■■■■■■■■■■ ■■■■■ ■■■■ •••il'l -i-i:::!:::! 1 ■■■■■B ■ ■■■■('■"■■■■■■■■■ESS! . .- . ■ :; ::;;■::::■. . .:::.:::: .... :: ::: ::■: :::::: : : :: ::::::::::::::::::::::::::::::::: : : : . :::::::::::;: !■■■ SSSSSS S S ■■ :: 1 ::i: "» -S-i 6 ItmiiWttmP^^^^^^^^B^^^ ::s : ■■■ 1 ■■■■ ■ PMM 1 lEll ':ii::::h:::i;::S:s:H:h-'::;:;::::::::::°^l^li^|:i^ 1 16 U 6 1 III Hi illllililiili IN! ■«■ ■■■■■■ ■■ ■«■■■ ■■■■■■■■■ ■■■■ ■■■■■ ■ ■ »! :::::! ■:::::::::::!:!>»:: ::::: :■ iU F:^::: :: :::::::::::;:: iSi: j:::: :: •:: ■ ■■ illBBB ■■ ■■■■■ ■■■■VB-Jk'« ■■■■ ■■■■■ ■ 'a ■" " : :::::::::::::■■:::::;::: i iiliiliiiiilili ■ifl ■■■■■ ■■■■■ ■■■■■ ■■■■■ ■■■■ ■■ ■■■■■ ■■■■■ ■■■■■■■■IB ■■■! ■■■■■I Wis: !■■■■■ ■■■■■■ :::::: ■::::: ;:;:;:;::::::; : :::»:; ;: !:;:; ;» ::: k:;: :: ::: 1R 11 llllillrlllllllllliii lllliilillillMiliili III ■■■■■ ■■ ■■■■ ■■ ■■ ;::: ; :;» :; ;; |:-:;|;;;-::;;:!;;::;;;;-|-::::;::;;:;:!-;:::: :;s: : ::ss :: :: ■■■■ ■ ■■■■ ■■ ■■ h + :■ ::z:S::: :zz: ::- :z::: :\::±:: :::■■::■ :■■■■■ ::: IMIMIII nillNIHI +H+H 1 ya![K!:::»""k-:::::!::'::!:|:n:»»:[;» Weeks 6 11 16 21 26 31 36 11 46 51 56 61 66 71 76 81 91 96 101 Pig. 25. variation of color, by weekly averages, of eggs produced bt dam for TWO years and bt progeny during early pullet production The heavy horizontal line in each division represents the character of the parent egg incubated; the heavy curve represents the production of the chick hatched; the li^ht curve represents the production of the progeny of the chick. The dotted Unes indicate that no eggs were produced during the periods which they cover MISCELLANEOUS STUDIES A few studies were made in addition to those relating solely to the degree of inheritance existing for the size, shape, and color characteristics. These are discussed in the following pages. Relationship of size and shape of eggs A study was made of a mixed assortment of pullets' eggs (table 55), which showed practically a zero correlation. This does not agree with results reported by Pearl and Curtis (1916). Some individuals, and some different strains and breeds, may possess characteristics the reverse of those of the strain of Single Comb White Leghorns used in these experiments. Study op Selections for Size, Shape, and Color of Hens' Eggs 251 ^ w I OM"*eoi3>icc 1-H i-H rS i-H CO CO to ^« ^ r-l r-l.-H o.-< «. ^ ^ ^ s? ' ^ «. .H ^ ^ ^ * W CO c§ " .-H rH M Tjl -* .-( N o •4i fc rt iO«5-*Tj(W (N-H CO g M»-(,H i-H-^-^OfflOO « lOrt o r lOrHr-ICOIMiO'«i<"*©0 rtCqi-l II a o s; e^ rti-(.-(Ti)(Mr-.osooco ,-(,-(cq^ 1 8 K i-t fH CO .-< CO iC CO CO so lO 1-1 i-H N rt 1-1 m Ni-H CO»OCO»OQ0t-.-i COeOi-1 rt (N (N C0(N50C»t*bc/iK)fr £>//x/s. 3.40 . S/Ta/jerse/ec/zo/? jb/h/s^ _ Co/or ^se/ec/zb/? iv'/ds.^. Year 1st 2d Pig. 26. standard deviations for successive years, grouped as to character The figures in parenthesis designate the number of birds available for the respective calculations 27. In figure 26 the studies are segregated into the three character groups. The reduction of the number of birds available for study in the fifth and sixth years makes the data for these years of doubtful value, altho the number of eggs used for each bird is in each case sufficient to make the standard deviation of real value. 254 Eael W. Benjamin In figure 27 the data for the three characters are combined both by a weighted and by an ordinary average. This figure does not show the definite tendency toward a reduction in the variabihty which is claimed by some other investigators (Pearl, 1909), altho if the data for the fifth and sixth years could be given as much value in this discussion as is given to the data for the first four years, a straight line fitted to the curve would show a distinct reduction in the standard deviation. The unweighted averages are shown in figure 27 because if it can be considered that the standard deviations calculated for the respective character >^yera^e of ihree choracfers, pyv/^hfed . „„ for number of t Omreighfecf aireragie ^ 2 60- ■ «. ..^ ^^..-s**" ^^ ^ -^,^>^ "v..^ " ' '^v^ ^ V 2 20- ^N^ \ ,.X \ J 2 00- \ \ \"^ 1 80- \\ \ \ 1.60. \\ \ ^ 1.40. \ 1.20. 2d 3d 4th 5th 6th Year 1st Fig. 27. standard deviations of all characters for successive years The figures in parenthesis designate the number of birds available for the respective calculations groups are based on a sufficient number of individuals to be trustworthy, none of these characters should be handicapped in the average if it hap- pened that a less number of individuals were available for that particular character than for the others. This is especially true since this is a comparison of standard deviations based on a grouping according to classes of widely different values. Variations in types of eggs produced during successive months and years The study of the variations of eggs produced during successive months and years was carried on with birds that began to lay in different months, as noted in table 58. The time of beginning to lay is varied enough in the data used here to nearly eliminate seasonal effects. Study of Selections for Size, Shape, and Color of Hens' EggS 255 TABLE 58. Pebcbntagb op Each Year's Flock Beginning to Lay in the Respective Months from Novembee to June, Inclusive Percentage of year's flock that began laying in respective months Mouth when laying began First year of pro- duction Second year of pro- duction Third year of pro- duction Fourth _ year of ' pro- duction Fifth year of pro- duction Sixth year of pro- duction November 0.3 21.7 29.6 28.2 11.2 9.0 1.1 8.6 28.0 28.4 22.6 9.7- 1.1 0.5 6'2 28.4 46.9 18.5 2'.6 2.6 43.6 48.6 2.6 5.6 5.6 33.3 49.9 5.6 December February March, . . 20.0 80 April June Size character The variations in the mean size of the eggs produced during the successive months by the size-selection birds are shown in figures 28 to 31. These curves are made up by calculating the mean for the first month's pro- duction of the first year, the second month's production of the first year, and so on for the succeeding months and years for each hen used, and then finding the mean for all available hens at each period. Data for eleven months of each year were available for a sufiicient number of birds to make the figures reasonably reUable. The size of the eggs produced by pullets increases fairly regularly during the year, but no real increase in the size of the eggs produced during the later years of production can be observed. It may seem that this statement is disproved by figure 30, but a glance at figure 28 shows that the size of the first year's production increases so rapidly that it causes the mean size to increase sHghtly. AU seasonal effects are eliminated in these studies, the birds being arranged in accordance with the month whent^ey began laying each year, irrespective of the particular month which that happened to be. It would seem that the wide fluctuations after the ninth month in figure 28, and after the seventh month in figure 29, may- be due to the fact that too few birds were available for study; but an apparent tendency for the size * of the egg to increase rapidly near the end of the laying season is observed. 256 Earl W. Benjamin /y0C7/7 for ^rsf /fea/7 for jreco/7c/ ^ Grama i^eors /yrocfucf—^ __ ^ s/Ar/h i/ears proc/acf. 64 -1 ' ' ' ■ — ' ' — ■ — ' ' ' ' 63 62 61 60 69 58 57 56 55 64 63 52 51 Month 1st 2d ■ 3d 4th 5th I 6th 7th 8th 9th 10th llth Fig. 28. monthly variation in size of eggs produced during a period op six YEARS The figures in parenthesis designate the number of birds available for the respective calculations 171 r'^"'^ ^o; /\ li*^ \ / , N. / y tf^A &4') 4r, x (IIW R3,^ y HO} (109) g5> gjt-- ^y^■ * ea JSX^ IH) ^.^ '^» ^"^ lito)^ -* 'i^'" J?-^ ^ Second uears T/t/zz/ i/earj ^cf/^/? (/ea/v ff/^h umars S/x^ t/eaz-j- 72- / (2) / nR / ' / Al 61 / / III A'> / , 15) / i pn / \ ' 1 i/?i ^ / \ ^ U, /' ^^2 68-, 33 63J E^I TtSJ -A=^ ^=^ Rff 35 5ri=~ 1 B» ^^=:^ .8; • / SiJ ^6) 7 \ / i£i. / • • ^;»^ *"" (,2)_ (ipl > ?5) \ / »iJ^"_ \ • (31 ( f' , ^N.. 'v k./ FiO * (II ••. ,3, .III lift — " n^*-*-- III trr( Month 1st 2d 3d 4th 6th 6th 7tb 8th 9th lOtb llth Pig. 29. monthly variation in size of eggs produced during a period of six YEARS The figures in parenthesis designate the number of birds available for the respective calculations Study of Selections fob Size, Shape, and Color of Hens' Eggs 257 It should be noted that the individuals whose data are used for the later months of the year, shown in figures 28, 29, and 30, are those that laid during the longest period and were very likely to be the highest pro- ducers (Rice, 1914). This would indicate an agreement with Curtis Grams 3/m/s n^/r/? //fis mec/n of -^S or /ess 56-60^ , . -^(0-50 6/-65 5/-55 7/-75 1:^^^ 62- 58 S4 50 46 h) (27) er'. (ew ■ y i ■ 1 1 I II I 1 1 ■ ■ ■ I 1 1 1 1 t^ -em o^J'f" I3iy ""^; Month iBt 2d 3d 4th 5th 6th 7th 8th 9th 10th llth Pig. 30. monthly variation in size of eggs produced during a period of six YEARS The figures in parenthesis designate the number of birds available for the respective calculations The curve representing the birds having a life mean of 45 or less does not lie entirely within that range because the whole six-years data on which the life mean is based is not available in monthly means for this chart (1914 a) and-Hadley (1919) to the effect that the conditions causing the production of a great many eggs will also cause the production of large .eggs. In order to see whether the results shown in figures 28, 29, and 30 were due to the selection of high-producing birds from the low producers, as suggested above, figure 31 was constructed for five individuals which 258 Eael W. Benjamin began laying in December and continued laying for about the same period as the others (until August). No material difference can be observed between the types of curves shown in figure 31, and those shown in figures 28, 29, and 30. There seems, then, to be no marked error due to the possible- selection of birds in the study of the random flocks, and it "is probable that the curves for heavy producers are not materiUly different from those for lower producers. . ^ J -' ) ' Grams 65 63 61 59 57- Deo. ^^^ •f^^*"^ a '***yy ^ • ••- o /7~ *.. f • •. A V • ^ s y 'yi f \ X H*te .--- . .1 / /^* \ y *«^ jr*^ . — " ***** *-*_ -^ / ^ "o™ ■^?-afc*'*ip «■»****-**, :yr_ 7 ^ «®o •ooa o ooooeo <^ ' ^ t^,^ ^ '■ "^ ^ - — "^ Jan. Feb. March April May June July Aug. - Fig. 31. mean monthly size records for five normal individuals for a period OF FIVE years After the great increase in the size of the eggs from the first to the second year, there seems to be a gradual decrease in the size of the eggs produced during successive years. This last statement does not agree with the results of Curtis (1914 a). . No decreased size of the eggs produced at the beginning aod at the end of the fitter is observed, as claimed by F6r6 (1898 b) and Curtis (1914 a), and there is no appreciable difference in the variations for the birds laying large, medium, and small eggs (fig. 30). Study of Selections fok Size, Shape, and Color of Hens' Eggs 259 Shape character In order to study the relative monthly and yearly shapes of eggs pro- duced, the data for shape selection were prepared for figures 32 to 35 in the same way that the data for size selection were prepared for figures 28 to 31. There is shown a tendency for the eggs produced each year, even in the pullet year, to have a gradually increasing index until the fifth or sixth month of production, after which this index gradually decreases until the season's production ceases (fig. 32). Index proefc/c/ jproc/ucA '3ccor7e/ /a j'ax//? uears Month 1st 10th nth Fig. 32. monthly variation in shape of eggs produced during a period of six YEARS The figures in parenthesis designate the number of birds available for the respective calculations According to figure 32, the eggs produced during the pullet year are of practically the same shape as those produced in later years. The difference may be considered insignificant. The reader should be warned against erroneous interpretation of the fifth and sixth years' production shown in figure 33, because of the very few individuals available for study for those years. As indicated in figure 34,- there seems to be no radical difference between the variation of the groupings according to the fife means of the birds. Where sHght differences are shown, these may usually be considered as being due to an insufficient number of individuals available for study. The five birds recorded in figure 35 showed no distinct character different from those shown in figures 32 to 34. 230 Earl W. Benjamin 3eaonc/ (/ec7/:s Th/'n/ t/ears /ou///? i/ears f/f/ih (/ecrrs S/jrt^ c/ecjrs Index procfucf pro(fuc/m • _ ^ro&ucA^ . .. ^.rtx/c/c/, ,,», M/=>/73K7<:/£7^r^nt nth Fig. 33. monthly variation in shape of eggs produced during a period of six YEARS The figures in parenthesis designate the number of birds available for the respective calculations Study of Selections fob Size, Shape, and Color of Hens' Eggs 261 Index B/rc/s f^/fh ///e n?e-c7/7 of eo-es 7o-r5 . . 65-70 75-eo III _^ t<^ ii?i \ £g>i»^ X ^'^^ \ 71 - ^J^ \ ^^ \ M - r rtJiO) > >k^ / « IfeSi.--' i^6) \ 79 - z\)jr y^ '"■•^ (f7) \ (4 f fer;^ ■>». ni^j \. ^i^"^ 65L'"^ ''^. (^.^ / ^ ■■^^X / IS-) r (-42) faR) / 3j 4^^ > (^ ^-. / •/ ^ / \ qei / \ (4S ^ / ^ << \ V ;?&! / / \ DO) \ / \ \ V \ r?) \ s?^«*^^ V*' \ \ 6.5 u> Month iBt 2d 3d 4th 5th 6tli 7th 8th 9th >: 10th 11th Pig. 34. monthly variation in shape of eggs produced during a period of six YEARS The figures in parenthesis designate the number of birds available for the respective calculations The curve representing the birds having a life mean of 60-65 does not lie entirely within that range because the whole six-years data on which the life mean is based is not available in monthly means for this chart 262 Earl W. Benjamin 75 — — 74 73 72 70 ^ ■ ^ _.— ._ • %^^ ^ ■^.»" - "~^ •^ y ^ " ^ "» v'^ ~ v^. / / ^* , ^- j/^ ^''^. 't^'^ .'"/'• • -li? x: "^ \ VI J /.' ,^^^ *°., /'o v* /^^ ''^ • ••' ••.. \ c^ « • '•. \ ..'/•j •. • • ••- /X 1 «^/ ^/ f - Dec. Jan. Feb. March April May June July Aug. Fig. 35. mean monthly shape records for five normal individuals for a period OF five years These results do not agree with deductions to be gained from Curtis (1914 a) or from Thompson (1908). It would appear from these results that the tension of the oviduct wall may gradually relax during the first five or six months of the bird's production each year, and then increase again as the season closes, causing at first a rounding of the egg and later a lengthening. Color character The study of the monthly production as to the variations of color is summarized in figures 36 to 39. There is a definitely increased amount of pigment in the eggs produced by the hens after their pullet year as compared with their first year's production (fig. 36). There is a distinct tendency for the eggs to become whiter as the production continues for the first five or six months, and then to become more tinted again toward the end of the season's production. It would seem that the amount of pigment is decreased during the period of most abundant egg production. As shown in figure 37, there is no distinct and gradual increase in the pigmentation of the eggs from the second to the sixth year's production, but during each year when enough birds are available for the data to be considered of value, there is a tendency for the same monthly fluctuations as are exhibited in figure 36. The grouping of the birds according to their life means in figure 38 shows the same monthly fluctuations as were previously observed. Study of Selections foe Size, Shape, and Color of Hens' Eggs 263 A^san ■for -/Frsf Color t^ears proof uc/- 5.8 5.6 5.4 5.2 5.0 4.8 4.4 4.2 4.0 3.8 3.6 3.4 3.2 3.0 2.8 2.6 2.4 2.2 Month 1st /^ea/f ■fyr deconc/ fo »_ s/x//? years proc/ucr/-_ yi+o • 1 J|29)\ \ \ \ ' UI37) pg; \ \ / ^} \ \ / / \ \ / / \ \ (133; /ts) \ ■'' ■^8) ' (I24-) ^^ ^^ .(423;^^ it32>_____ 021) tisSi— — 'faa / \ \ f7Q) _, / \ v, us^i. (IE6> •^ ^ (SK) > ^9; ^"^^ ije;^ — \ \ vV2> ''>9 3d 4th 5th 6th 7th 8th 10th 11th Fig. 36. MONTHLY VARIATION IN COLOR OF EGGS PRODUCED DURING A PERIOD OF SIX YEARS The figures in parenthesis designate the number of birds available for the respective calculations 264 Earl W. Bf,n.ia.min ^prcx/ucK— . — .m.procfucf .....^/T3(7Z/ V ?' \ «.. \ \ \ /J' ^,, \ V (13) > gs) "\ a!L_^ ^' (■ r^'^ iC*'*' s „. \ v \, , .>j ^*=1; *tr*^ "f' >A (4-; .^ 8) > ^ S jU^x ^ " • ^" t9j • *" V \ ^''*«. .2) r \ <^* 4 a'.««' 'V \ \ l£J \ \ \ \ \ \ \ \ 2 ■ \ fzi \ \ _, ' 1.6 . > f) Month Ifit 2d 3d 4th 5tb 6th 7th 8th 9th 10th 11th Fig. 37. monthly variation in color of eggs produced during a period of six YEARS The figures in parenthesis designate the number of birds available for the respeotive calculations Study of Selections fob Size, Shape, and Color of Hens' Eggs 265 Color B/rds H^/f/7 //fe ' rr?ea/7 of /-a — -9-5. Z—3 5-6 J— ??__ .—6-7' o—7'-8»'*» 4.2. 3.S 3.4 3.0. 2.6 2.2 1.8 1.4 Month iBt |3) ^ 8S-^ ^^ g^ ».8J^ ;57i,.__ p; 11th Fig. 38. monthly variation in color of eggs produced during a period of six YEARS The figtires in parenthesis designate the number of birds available for the respective calculations 266 Eael W. Benjamin The results of this study agree in general with the findings of other workers, already discussed. The record of five individuals in figure 39 agrees in general with the records in figures 36 to 38. Color' 5.0- 3.0 2.0 1.5. ^^ >\ a k "^ \ • • J V • \ / \ V • • *'*•. • • my X \ ;••• •« • • •♦. • 5f \ \ K '••.. • /* 1, ^^ « •• ,• V / • \ ^. -,-'■ X y • \ ^^^^ \ y • \ ^ . ^ f'^-w^ ^ • ( "\- jX N/^ ^^'^ c^ /. \ y^ ^•c^ =^o^ 1 *>»>»»^ '^ / ^* — ^s v***^ •n / ^ Dec Jan. Feb. March April May June July Aug. Fig. 39. mean monthly color records for five normal individuals for a period of five years Variations in types of successive individ/iml eggs An opportunity is furnished by figures 18, 21, and 24 (pages 243, 246, and 249) to observe how the types of successive eggs may be affected by the general type of the bird and the rate of laying. In figure 18 it may be noted that in nearly every instance when two or more eggs are laid on successive days, the si.w gradually diminishes until the bird rests for one or more days, when the size of the next egg is again larger. This agrees with many more charts constructed for this same character, and is in entire 'accoMance with Curtis (1914 a). A study of figure 21, which agrees in general with other charts constructed for the shape character but not reproduced here, reveals the fact that in a large proportion of the instances when two or more eggs are laid in succession, the egg laid later is rounder than the one laid earlier. About 60 per cent of the cases showed an increase in the index, 25 per cent showed no change, and 15 per cent showed a decrease. This condition may Study of Selections fob Size, Shape, and Color of Hens' Eggs 267 result from the less tension exerted by the oviduct wall on the second egg when it closely follows an earlier one. After the bird has rested for a day er two, the oviduct wall regains its tension and the next egg is longer. The egg color, for the birds that were studied in this regard, seemed to be gradually intensified in eggs laid on successive days (fig. 24). About 50 per cent of the cases showed an intensification of color, 25 per cent showed no change, and 25 per cent showed a decrease of color. Variations in types of eggs produced in different calendar months Since it is known that the commercial eggs received in the markets vary somewhat from month to month as to their average size and color, and possibly as to their shape, it was thought well to ascertain what information could be obtained on this point from the data at hand. These variations for size, shape, and color, respectively, are illustrated in figures 40, 41, and 42. The results shown in figure 40 do not agree with those of Hadley (1919), but tend instead to agree in general form with figures 28, 29, and 30. Grams 0^ - \ / 60 \ / \ / n8 \ / / 5A / "•^^ ^^. / 54 ^v -^ — ■^^^ ^ ^^ y^ a?, Feb. March April May June Joly Aug.' Sept. Oct. Nov. Fig. 40. mean mont^y variation in size of eggs produced in certain calendar t months for a period of six years. LAY IN FEBRUARY record of ten individuals beginning to No increase of egg size during the period of heavier production can be observed here, as found by Hadley (1919) with White Plymouth Rocks. The results shown in figures 41 and 42 agree closely with the results previously obtained for mixed flocks, and need no further comment here. 268 Earl W. Benjamin Index 72. S- A y X. y >s, / ^^ 70 / '"'"**-».^ 69 5- / / 68 5- ^^^ 68.0 / / / / 66.0- Jan - II Feb. '{T" March " i April ] " ' May 3 June "i \ July Aug, Sept. Oct. Fig. 41. mean monthly variation in shape of eggs produced in certain calendar months for a period of six years. record of ten individuals beginning to lay in january Color 4.2- 4.0- V- i L^^ 3.9- 3 8— -V —i \ / V / 3.5<. \ / 3 4- \ / 3 3- \ / 3.2- \ ♦ / 3 1 \ *.' / \ / x^ / \ / 1..9- N / \ / Feb, March April May June July Aug. Sept. Oct. Fig. 42. MEAN MONTHLY VARIATION IN COLOR OF EGGS PRODUCED IN CERTAIN CALENDAR MONTHS FOR A PERIOD OF SIX YEARS. RECORD OF TEN INDIVIDUALS BEGINNING TO LAY IN FEBRUARY Study of Selections for Size, Shape, and Color of Hens' Eggs 269 Relation between vigor of the chick and size of the egg from which it was hatched In 1911-12 a separate record of the vigor of the chicks, as well as of their weight, was made for the first forty weeks of their hves. The vigor was recorded in four classes: Very Poor (V.P.), Poor (P), Good (G), Very- Good (V.G.). Correlation tables such as table 59 were constructed TABLE 59. Vigor of Chicks at the Age of Four Weeks, Subject; Weight (in Grams) OP Eggs from Which the Respective Chicks Were Hatched, Relative Coefficient of correlation = .381 ± .064 44^6 46-48 48-50 50-52 52-54 54-53 55-58 58-80 60-62 62-64 64-66 " I V. p. 1 ■ p. 1 3 1 1 1 1 1 9 G. 5 1 6 5 4 3 1 2 27 V.G. 5 4 8 8 2 8 4 4 43 8 11 14 13 10 80 for each four weeks of the chicks' lives. A summary of the results of the correlation tables (space for which caimot be taken here) is given in table 60. In this table the respective weight correlations also are shown. TABLE 60. Summary of Coefficients op Correlation Found in Studying the Relation of the Weight and Vigor op the Chicks, Subject, and the Weight op the Eggs prom Which the Respective Chicks Were Hatched, Relative Age of chick Coefficient of correlation Number Chick vigor Cliick weight viduals * .844±.021 .461 ±.060 .311±.067 .362±.068 .38D±.068 .263±.073 .308±.072 .296±.077 .509±.064 .392±.074 .397±.079 82 4 weeks .38i±.664 .331 ±.086 .334±.069 .338±.070 .159±.077 .176±.077 .174±.081 .296±.080 .075±.087 .110±.093 80 82 12 weeks 75 72 20 weeks 73 73 28 weeks 65 32 wppks 61 36 weeks 60 51 *The vigor was not recorded at the one-day-old period, because it was impossible to designate the dif- ferent classes at this early age. In recording the data for these vigor studies, a special effort was made to be sure that the record for vigor was made independently of the record 270 Earl W. Benjamin for weight. Of course these two factors are hkely to be very closely associated. The weight correlations are much more distinct than those for vigor during most of the year. The vigor correlations decreased after the early weeks, until some very severe winter weather just previous to the thirty-sixth week's recording. After the thirty-sixth week, how- ever, abnormally early spring weather prevailed, the vigor of all birds improved wonderfully, and the correlation entirely disappeared. From the observations just noted, it seems that the test of the vigor of a chick, that is to say, when the size of the parent egg is of real benefit, comes during the season of greatest hardship to the birds. The weights are not affected by the seasonal conditions quite so definitely as is the vigor. Relation between male and female weights for chicks of the same age Diu-ing the first forty weeks of the 1911 hatch, and the first seventy-six weeks of the 1912 hatch, the male and female weights were averaged TABLE 61. Constants Representing X in the Formula: Weight : : X : 1 Female Weight : Male 1911 offspring 1912 offspring Age Constant Age Constant .89 .91 .81 .78 .75 .75 .88 .89 .92 .90 .97 4 weeks ... . 4 weeks 72 8 weeks 12 weeks .84 12 weeks .86 16 weeks 16 weeks. . . . 88 20 weeks .87 24 weeks 24 weeks\ * 28 weeks 28 weeks . . . . 95 32 weeks .91 36 weeks 36 weeks ,95 40 weeks 40 weeks. . . . .94 .85 .83 52 weeks . . .89 .84 60 weeks .81 -■ 64 weeks . . . .82 68 weeks .85 72 weeks .82 .83 * No male weights were obtained at this age in 1912. Study of Selections fob Size, Shape, and Color of Hens' Eggs 271 separately, and for each four-weeks period a figure was obtained to rep- resent X in the following ratio: Female weight : male weight :: x : 1 A Kst of all such constants obtained is shown in table 61. In studying correlations for the- weeks shown in table 61 for the 1911 offspring, and for the- one-day-old period of the 1912 offspring, the male weights were multiplied by their respective constants and used with the female weights. After the above periods, and for all other offspring, no male weights were used. These constants correspond rather closely to the con- stant 0.93 representing the same ratio for human stature in mature per- sons, found by Galton." Relation between size of the chick and size of the egg from which it was hatched A preliminary study was made of the 1911 and 1912 offspring, before the records for the later years were available, to determine the relation between the size of the chick and the size of the egg from which it was Er /9//c^/vrh^ ^ . /9/eoffJA^'/?7, y^*// tf-zw/^A^^woi '" J8 20 B. ' -\i\. 1 \l\ - - - ./^tJt *:: "jk.^^-'%^c=»,^-i<;s. - i\ ^:^-^^'5._,.'v,^'^>t- \ , R>'