SF UC-NRLF I 33 THE HERITANCEOFTHE SIZE, SHAPE AND COLOR OF HENS' EGGS A THESIS PRESENTED ': THE DI:< DOCTOR OF PHILOSOPHY BY EARL WHITNEY BENJAMIN 1914, 1920 EXCHANGE 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, 1326^ • V : :•"'• :..: •:!L! ; EXCHANGE CONTENTS PAGE Review of literature 195 Methods of investigation 198 Size character 199 Shape character Photographing the eggs for size and shape studies 202 Color character 201 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 244 Miscellaneous studies 250 Relationship of size and shape of eggs '. 250 Incubation effects of egg type 252 Relative variability of the productions of successive years 253 Variations in types of eggs produced during successive months and years 254 Size character 255 Shape character 259 Color character 262 Variations hi 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 478389 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' EGGS1 E!AKL 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 commercial thirty-dozen cases; this means an egg about 2f 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 published 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)2 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 (19 14 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 Fere (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 which 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 OF SELECTIONS FOR SIZE, SHAPE, AND COLOR 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,3 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 hatched 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 immaturity of the parent, to the smaller size of the egg, 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 that 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 litter 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), Fere (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 abnormalities reported might, of course, prove to be inherited, especially such as the double yolks found by Glaser (1913); however, since this publication is concerned with nonnal eggs, further discussion of rare monstrosities may be omitted. The coloration of the shells of eggs has long been a subject of interest to oologists. 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 Pearl, 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 prematurely, 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 lichnoxan thine. 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 mendelian 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 function 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 many 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. 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 FOB 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 commercial 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).4 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. After 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 all 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, 4 This balance was imported by Cornelius Kahlen, New York City. 200 EARL W. BENJAMIN FlG. 7. SPECIALLY DESIGNED DIRECT-READING BALANCE FOR WEIGHING EGGS AND CHICKS 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 compartments 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 and FlG. 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 J-inch face (fig. 8).5 One micrometer was adjusted for the egg length and one for the egg width. 5 These were manufactured by Brown & Sharpe, Providence, Rhode Island. 202 EARL W. BENJAMIN FlG. 9. LIGHT, AND FRAME FOR HOLDING EGGS, AS USED FOR THE SHADOW PHOTO- GRAPHIC PROCESS The wire circle around the light 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 right 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. PHOTOGRAPHING 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 during 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.6 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.7 The eggs are placed on the film as shown in figure 9, and are held in 6 It was necessary to use high-contrast paper for this work, in order to obtain distinct black and white tones. 7 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 FlG. 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, if 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 J 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 9x 11- inch sheet are placed on the film, they are arranged evenly by means of a separate frame shown in figure 9, which divides the 9x1 1-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 light 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 outlines 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. COLOR CHARACTER 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 be matched to other eggs of standard colors. s By a careful inspection of all eggs produced on the plant for several cfcays, 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 MEMOIR 31 PLATE VII PLATE VII KEY TO COLOR NOTATION USED FOR COLOR STUDIES OF EGGS Color notation number Equivalent in Repertoire de Coideurs Plate Ton (Tone) 1. ..1 11 ..1 ......1 2 3 ....1 1 2 3 4 1 2 3 11 4 ....11 2 10 10 5 6 7 8 9 . 9 9 10 11 . . . .312 ....312 67 ..36 .....68 68 2 1 1 12 13 ; 14 ..1 2 3 4 15 16 68 17 68 206 EARL 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 light 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 later. 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 slight. 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 CHARACTERS 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 8 Repertoire de couleurs. Published by La Socie'te Frangaise des Chrysanthe'mistes and Ren6 Oberthur, with the collaboration of Henri Dauthenay and others. 1905. STUDY OF SELECTIONS FOR SIZE, SHAPE, 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 FlG. 11. TYPE OF HOUSE USED FOR STOCK AFTER 1913 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 variability 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 9 The life mean for the sire was 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 the class; when a class is designated by two figures, the upper figure is included in 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 OF EGG SIZE (WEIGHT IN GRAMS) DURING FIRST YEAR OF PRODUCTION, SUBJECT; DIFFERENCE BETWEEN EGG-SIZE LIFE MEAN FOR DAM AND FOR SIRE, RELATIVE Coefficient of correlation = .012 ± .052 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 1.0-1.5 1 2 1 4 1.5-2.0 2 1 1 1 2 1 1 9 2.0-2.5 4 2 2 4 2 1 7 4223 33 2.5-3.0 11 5 3217 2 8 3 3214 1 53 3.0-3.5 6 3 3 4 1 7 5 2 7 6111 47 3.5-4.0 3 2 1 1 2 1 1 3 1 1 17 4.0-4.5 1 1 1 3 4.5-5.0 0 5.0-5.5 0 5.5-6.0 1 1 6.0-6.5 1 6.5-7.0 0 7.0-7.5 1 1 26 13 10 9 4 13 16 17 13 20 5 10 110001001 169 TABLE 2. STANDARD DEVIATION OF 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 7 8 9 10 11 12 13 14 15 16 17 18 19 1.5-2.0 1 1 2 2.0-2.5 1 2 2 2 1 22 1 13 2.5-3.0 2 3 1212 2 4 4 2 1 3 27 3.0-3.5 2 2 2 1 3 10 3.5-4.0 1 1 2 4.0-4.5 1 1 2 000 56 210 EARL W. BENJAMIN TABLE 3. STANDARD DEVIATION OF EGG SIZE DURING THIRD YEAR OF PRODUCTION, SUBJECT; DIFFERENCE BETWEEN EGG-SIZE LIFE MEAN FOR DAM AND FOR SIRE, RELATIVE Coefficient of correlation = .13 ±.12 1 2 3 4 5 6 • 7 8 9 10 11 12 13 14 15 16 17 18 19 1.5-2.0 1 - 1 2.0-2.5 1 1 1 3 2.5-3.0 1142 131 13 3.0-3.5 1 1 1 2 1 6 3.5-4.0 1 1 2 4 4.0-4.5 0 4.5-5.0 0 5.0-5.5 j 1 5.5-6.0 1 1 1302140 43220000001 20 TABLE 4. STANDARD DEVIATION OF EGG SIZE DURING FOURTH YEAR OF PRODUCTION SUBJECT; DIFFERENCE BETWEEN EGG-SIZE LIFE MEAN FOR DAM AND FOR SIRE, RELATIVE Coefficient of correlation = — .16 ± .20 10 11 12 2.0-2.5 1 1 1 3 2.5-3.0 1 1 1 3 3.0-3.5 2 1 3 3.5-4.0 0 4.0-4.5 1 1 2 TABLE 5. STANDARD DEVIATION OF EGG SHAPE DURING FIRST YEAR OF PRODUCTION, SUBJECT; DIFFERENCE BETWEEN EGG-SHAPE LIFE MEAN FOR DAM AND FOR SIRE, RELATIVE Coefficient of correlation = .18 d= .08 .01 .02 .03 .04 .05 .06 .07 .09 .10 .11 .12 .13 .14 .15 .16 .17 .18 1.0-1.5 1 1 1.5-2.0 1 1 1 1 4 2.0-2.5 1 4 3 1 1 1 1 1 1 1 1 16 2.5-3.0 4 2 2 3 2 1 1 2 2 3 1 1 24 3.0-3.5 1 2 1 2 2 1 2 11 3.5-4.0 1 2 2 1 4 10 4.0-4.5 1 1 2 4.5-5.0 1 1 2 G 9 736542092520103 70 STUDY OF SELECTIONS FOR SIZE, SHAPE, AND COLOR OF HENS' EGGS 211 TABLE 6. STANDARD DEVIATION OP EGG SHAPE DURING SECOND YEAR OF PRODUCTION, SUBJECT; DIFFERENCE BETWEEN EGG-SHAPE LIFE MEAN FOR DAM AND FOR SIRE, RELATIVE Coefficient of correlation = .14 ± .10 .01 .02 .03 .04 ..05 .06 .07 .08 .09 .10 .11 .12 .13 .14 .15 .16 .17 .18 0.5-1.0 !1 1 1.0-1.5 0 1.5-2.0 1 1 2 2.0-2.5 21111 1 7 2.5-3.0 11 211 1 1 8 3.0-3.5 3111 1 1 8 3.5-4.0 1 1 1 3 4.0-1.5 1 1 2 4.5-5.0 0 5.0-5.5 1 1 533324310020310101 32 TABLE 7. STANDARD DEVIATION OF EGG SHAPE DURING THIRD YEAR OF PRODUCTION, SUBJECT; DIFFERENCE BETWEEN EGG-SHAPE LIFE MEAN FOR DAM AND FOR SIRE, RELATIVE Coefficient of correlation = .13 ± .18 .01 .02 .03 .04 .05 .06 .07 .08 .09 .10 .11 .12 .13 .14 2.0-2.5 1 1 2 2.5-3.0 2111 1 6 3.0-3.5 1 1 2 3.5-4.0 1 . 1 l 3 4.0-4.5 0 4.5-5.0 0 5.0-5.5 0 5.5-6.0 0 6.0-6.5 0 6.5-7.0 1 1 30221301000011 14 TABLE 8. STANDARD DEVIATION OF EGG SHAPE DURING FOURTH YEAR OF PRODUCTION, SUBJECT; DIFFERENCE BETWEEN EGG-SHAPE LIFE MEAN FOR DAM AND FOR SIRE, RELATIVE Coefficient of correlation = .45 ± .20 .01 .02 .03 .04 .05 .06 .07 .08 .09 .10 .11 .12 .13 .14 1.5-2.0 j 1 2.0-2.5 2 1 3 2.5-3.0 1 1 3.0-3.5 2 1 3 3.5-^.0 1 1 2 10 '212 EARL W. BENJAMIN (N COCOINrHrH t-^ § 0 1-1 0 1 0 £ 0 0 H" 0 1 10 T-H 1-1 1 H Oi 0 o &B 10 0 O S CO U W 0 o Q CO r£ *~ 10 0 CC t>-' 0 « q 0 0 H Q -H «5 0 >H ^ CO CO 1 3 II o 0 _-M ^^ PI CO 0 « •I U5 0 DURIN BAN FC 1 o "5 CO rH - 3^ Is o +3 "• rH CO t^ 00 (N IN _| rH 8 §^ i o COCHIN rH i- r n O o " i-5 o »o ^H^^H ^H ^H ' »O fc 0 CO O w CO I1 o CO """""' 0 r* ^-t ,H rH CO r-t rH rH £ g IN W P Q g 0 0 O >0 O '0 O >0 O "0 O iO O 10 O iO Q 1C O 1C O !Ot>-OOt^O-OiNiOl--OOiCiOCO •>OO'CO'CG»OOiOOiOOiOOiOO'OO>COiOO>O O 1^ O (N >C t^ O IN 10 1^ O IN 1C t- C) C5 O rH rH rH rH (N IN IN IN CO CO Co''CO Tji **•#'# K) 1C lO ic' STUDY OF SELECTIONS FOR SIZE, SHAPE, AND COLOR OF HENS' EGGS 213 TABLE 10. STANDARD DEVIATION OF EGG COLOR DURING SECOND YEAR OF PRODUCTION, SUBJECT; DIFFERENCE BETWEEN EGG-COLOR LIFE MEAN FOR DAM AND FOR SIRE, RELATIVE Coefficient of correlation = .43 db .07 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 0.5 7.0 7.5 8.0 8.5 9.0 9.5 0.25-0.50 1 1 0.50-0.75 1 1 0.75-1.00 4 3 7 1.00-1.25 2322 1 10 1.25-1.50 312 21 2 11 1.50-1.75 3 1 122 9 1.75-2.00 1 111 5 2.00-2.25 112 3 7 2.25-2.50 1 1 1 3 2.50-2.75 2 1 1 4 2.75-3.00 1 1 2 3.00-3.25 1 1 2 3.25-3.50 1 1 2 3.50-3.75 0 a. 75-4. 00 1 1 4.00-4.25 1 1 0 4'.50-4.75 1 1 4.75-5.00 0 5.00-5.25 0 5 . 25—5 . 50 0 5.50-5.75 1 1 12 15 4 11 00000 1 68 TABLE 11. STANDARD DEVIATION OF EGG COLOR DURING THIRD YEAR OF PRODUCTION, SUBJECT; DIFFERENCE BETWEEN EGG-COLOR LIFE MEAN FOR DAM AND FOR SIRB, RELATIVE Coefficient of correlation = .52 zh .13 0.50-0.75 U.u ft *U l.u — . vJ .*- ,«J o.w o . 0 *±.v/ *±.*J u ,\J ij.o \J ,\J u.o i.v/ i.tj o,v/ 0.0 «j.^ */.u 1 1 0.75-1.00 211 4 1.00-1.25 1 2 3 1.25-1.50 1 1 3 1.50-1.75 2 1.75-2.00 1 1 2 2.00-2.25 0 2.25-2.50 0 2.50-2.75 1 1 2.75-3.00 1 1 3.00-3.25 1 1 3.25-3.50 1 1 3.50-3.75 1 1 3.75-4.00 0 4.00-4.25 0 4.25-4.50 0 4.50-4.75 0 4.75-5.00 0 5.00-5.25 1 42120131 0000000001 21 214 EARL W. BENJAMIN TABLE 12. STANDARD DEVIATION OF EGG COLOR DURING FOURTH YEAR OF PRODUCTION, SUBJECT; DIFFERENCE BETWEEN EGG-COLOR LIFE MEAN FOR -DAM AND FOR SIRE, RELATIVE Coefficient 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 1.00-1.25 1 4 5 1.25-1.50 . 0 1.50-1.75 1 1 1.75-2.00 1 1 2.00-2.25 0 2.25-2.50 1 1 2.50-2.75 0 2.75-3.00 0 3.00-3.25 0 3.25-3.50 1 1 3.50-3.75 0 3.75-4.00 1 1 1100003040000000001 10 TABLE 13. SUMMARY OF CORRELATIONS BETWEEN STANDARD DEVIATION OF EGG CHAR- ACTERS DURING EACH OF THE FlRST FOUR YEARS OF PRODUCTION, SUBJECT, AND DIFFERENCE BETWEEN RESPECTIVE LIFE MEANS FOB DAM AND FOR SIRE, RELATIVE Selection Year of production Coefficient of correlation r Er" Number of indi- viduals Size First 012± 052 0 23 169 Second -.28 ±.08 3 50 56 Third .13 ±.12 1 08 29 Fourth -.16 ±.20 0.80 11 Shape First .18 ±.08 2.25 70 Second .14 ±.10 1.40 32 Third Fourth .13 ±.18 .45 ±.20 0.72 2.25 14 10 Color First Second. . . . .13 ±.05 43 ± 07 2.60 6 14 174 68 Third 52 ± 13 4 00 21 Fourth .... .... .55 ±.15 3.67 10 STUDY OF SELECTIONS FOR 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 it is seen that =- for the sire ranges from 3 to 18; for the dam, from 4 .t^r to 22; and for the average of both parents, from 8 to 39. In table 24 it is seen that tpr ranges, for size, from 4 to 10; for shape, from 3 to 8; and .Lr for color, from 18 to 39. TABLE 14. TOTAL AVERAGE SIZE (WEIGHT IN GRAMS) OF PRODUCTION OF THE OFF- SPRING, SUBJECT; SIZE RECORD FOR SIRE, RELATIVE Coefficient of correlation = .36 ± .04 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 33 1 1 38 0 40 0 42 0 41 0 46 1 1 48 3 2 2 1 1 1 1 1 12 50 4 3 2 2 3 1 2 17 52 2 2 3 5 56 111 2 28 51 2 3 2 4 7 231 121 5 33 53 2 1 2 2 5 2 4 13 121 6 32 53 1 1 1 2 2 11 311 9 23 60 1 1 1 1 3 4 11 6J 1 1 1 2 5 61 1 1 3 5 66 1 111 4 88 0 70 o 72 0 74 1 1 13 0 0 0 5 13 3 0 13 15 24 9 10 4 1 8 8 5 0 33 173 216 EARL W. BENJAMIN a TO 3 M Q ^ o O S c § o oo u 3 s 0 S o X 0 | J§ O o" -fl x o "5 t-H (M CO CO •-! 25 00 »-H T;<^H 0 TO L^ '^ . 1 . 1 ^3 *3 H ts3 1O H 03 S NN 3 10 d H § C^J TO r-( CO i-l (M j 03 (NTOr-l H 00 TfrH H Tf* 13 0 ^ **l r-l — 1 1 »' fe 0 «§ ° 1 1; «-. 0 ^ S 55 0 2-^o TH T-H T-H Tj< T-H IN H d S 0 GO 0 62 0 •U 0 fit', 1 1 121 6 68 22 1 5 70 1 312 53 1 1 17 72 1 32272 1311 23 74 1121 12 1 9 76 312 11 8 78 1 12 4 80 ! 1 2 102000200 126 10 0187002 734 02 76 TABLE 19. TOTAL AVERAGE SHAPE OF PRODUCTION OF 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 * 1 1 56 1 1 58 0 60 0 62 0 64 0 66 1112 1 6 68 1 1 2 1 5 70 1 1 1 5 4 3 11 17 72 1132 2 4 5 3 1 1 23 74 1 2 1 3 1 1 9 76 1 3 1 3 8 78 2 2 4 80 2 2 100000003032574 18 13 12 24 1 176 220 EARL W. BENJAMIN TABLE 20. TOTAL AVERAGE COLOR OF PRODUCTION OF THE OFFSPRING, SUBJECT; COLOR RECORD FOR SIRE, RELATIVE Coefficient of correlation = .53 ± .03 1.0-1.5 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 6.0-6.5 6.5-7.0 7.0-7.5 7.5-8.0 8.0-8.5 8.5-9.0 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 3 2 3 1 9 5 5 1 2 2 15 9 1 6 5 1 11 33 2 10 2 1 8 7 8 38 1 5 2 1 6 1 2 1 19 2 3 3 11 3 2 24 1 1 2 5 1 2 12 2 7 2 1 12 1 1 1 1 1 1 6 1 1 1 3 2 2 1 1 3 3 8 3 4 6 13 26 1 1 1 22 1 8 0 1 1 40 29 47 12 39 6 17 216 TABLE 21. TOTAL AVERAGE COLOR OF PRODUCTION OF THE OFFSPRING, SUBJECT; COLOR RECORD FOR DAM, RELATIVE Coefficient of correlation = .67 ± .03 1.0-1.5 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 6.0-6.5 6.5-7.0 7.0-7.5 7.5-8.0 8.0-8.5 8.5-9.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 i.5 7.0 7.5 8.0 6 3 9 8 2 1 2 2 15 5 10 7 3 2 1 3 1 1 33 1 3 7 9 4 2 4 1 3 4 38 212 4 2 2 2 1 2 1 19 4 7 5 2 2 2 2 24 6 1 1 1 1 1 12 1 1 3 2 1 2 1 1 12 1 1 1 2 6 1 1 1 3 1 1 , 2 1 142 8 1 1 8 11 5 26 1 1 1 2 1 2 8 0 1 1 3 11 42 43 18 12 11 11 13 14 14 14 216 STUDY OF SELECTIONS FOR SIZE, SHAPE, AND COLOR OF HENS' EGGS 221 TABLE 22. TOTAL AVERAGE COLOR OF PRODUCTION OF THE OFFSPRING, SUBJECT; AVERAGE COLOR RECORD FOR SIRE AND DAM, RELATIVE Coefficient of correlation = .79 ± .02 1.0-1.5 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 6.0-6.5 6.5-7.0 7.0-7.5 7.5-8.0 8.0-8.5 8.5-9.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 3 2 l 2 1 9 3 4 1 2 4 1 15 7 2 7 1 10 4 1 1 33 6 2 6 8 13 2 1 38 1 3 2 7 3 1 2 19 3 3 11 7 24 1 1 4 4 2 12 4 5 1 1 1 12 2 3 1 6 1 1 1 3 1 1 2 1 3 13 8 1 1 2 5 17 26 1 2 221 8 0 1 1 22 18 24 45 49 10 12 21 216 TABLE 23. SUMMARY OF CORRELATIONS BETWEEN TOTAL AVERAGE CHARACTERS OF PRODUCTION OF THE OFFSPRING, SUBJECT, AND AVERAGE CHARACTERS OF PARENTS, RELATIVE Correlated parentage Character studied Coefficient of correlation r Er Number of indi- viduals Sire Size 36db 04 9 173 Shape . 21 ± 07 3 76 Color 53± 03 18 216 Dam Size .22± 05 4 173 Shape 47 -t 06 g 76 Color .67±.03 22 216 Average of sire and dam Size 42± 04 10 173 Shape 49± 06 g 76 CoW , 79± 02 39 216 222 EARL W. BENJAMIN fABLE 24. SUMMARY GIVEN IN TABLE 23 ARRANGED ACCORDING TO CHARACTERS Character Correlated parentage, Coefficient of correlation r Er Number of indi- viduals Size Sire .36=t.04 9 173 Dam .22±.05 4 173 Sire and dam .42db.04 10 173 Shape Sire 21 ± 07 3 76 Dam 47± 06 8 76 Sire and dam . . .49db 06 8 76 Color Sire . .53±.03 18 216 Dam . .67±.03 22 216 Sire and dam .79±.02 39 216 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 quality of either the male or the female parent will affect the type of egg to be produced by the offspring, with the female having slightly 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 prevailing 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, STUDY 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 CHARACTERS OF BIRDS AVAILABLE FOR USE IN CALCULATING DATA FOR FIGURES 12 TO 14 Character type Mating Mean character for sire Mean character for dam Mean character for progeny Size Large sire and small darn 59 6 51.5 54.3 Small sire and large dam 51.7 60.6 53.9 Large sire and large dam 60.3 59.6 57.2 Small sire and small dam 51 7 51 7 51.6 Shape Round sire and long dam .... 73 0 69 3 71.5 Long sire and round dam 67 0 75.4 72.5 Round sire and round dam . 73.0 76.0 75.0 Long sire and long dam. 65.4 69.1 71.0 Color Brown sire and white dam White sire and brown dam 4.81 2 11 2.34 4 78 3.00 3.27 Brown sire and brown dam 4 56 4 55 3.75 White sire and white dam 2 34 2 19 2.60 Large Small Prog- are dam eny (25) (49) Small Large Prog- sire dam eny (18) (81) Large Large Prog- sire dam eny (23) '(41) Small Small Prog- sire dam eny (17) (39) FlG. 12. MEAN SIZE CHARACTERS OF SIRES, DAMS, AND PROGENY IN ALL MATINGS The figures in parenthesis designate the numbers of birds available for the respective calculations 224 EARL W. BENJAMIN Shape index Round Round Prog- sire dam eny U) (2) FlG. 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 Prog- sire dam eny (3) (9) Long Round Prog- sire dam eny (10) (26) Long Long Prog- sire dam eny (16) (46) Color Brown White Prog- sire dam eny (27) (70) White Brown Prog- sire dam eny (12) (30) Brown Prown Prog- sire dam eny (33) (70) White White Prog- sire dam eny (27) (29) FlG. 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 FOR 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 character 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 tho 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 figures 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 58.6% Large sire Small sire Large sire Small sre Small dam Large dam Large dam Small dam FlG. 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 complications 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 Round sire Long dam Long sire Round dam FlG. 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- Brown White dam Brown sire Brown dam White sire White dam FlG. 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 bath 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 summarized 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.10 g- 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. 10 The terms pullet and hen, as use! in this memoir, refer to female birds during their first season of production and during their later seasons of production, respectively. 228 EARL W. BENJAMIN TABLE 26. MEAN SIZE (WEIGHT IN GRAMS) OF FIRST YEAR'S PRODUCTION OF BIRDS, SUBJECT; SIZE OF PULLETS' EGGS FROM WHICH RESPECTIVE BIRDS WERE HATCHED, RELATIVE Coefficient of correlation = .40 db .063 45 47 49 51 53 55 57 59 61 63 65 46 1 1 48 1 2 2 2 2 9 50 1 1 5 2 1 1 11 52 1 1 1 4 1 2 1 11 54 1 1 5 3 1 11 56 1 3 2 3 4 3 1 17 58 2 1 4 1 1 1 2 12 60 1 2 1 4 62 1 1 1 3 64 1 1 66 1 1 13 6 20 10 11 81 TABLE 27. MEAN SIZE OF SECOND YEAR'S PRODUCTION OF BIRDS, SUBJECT; SIZE OF PUL- LETS' EGGS FROM WHICH RESPECTIVE BIRDS WERE HATCHED, RELATIVE 47 Coefficient of correlation = .37 ± .103 49 51 53 55 57 59 61 50 1 1 52 1 54 1 1 2 1 56 1 3 1 1 1 58 1 2 1 1 1 60 1 2 1 1 1 62 1 1 64 1 1 1 66 68 70 1 2 1 5 7 6 6 2 3 0 0 1 33 STUDY OF SELECTIONS FOR SIZE, SHAPE, AND COLOR OF HENS' EGGS 229 TABLE 28. MEAN SIZE OF THIRD YEAR'S PRODUCTION OF BIRDS, SUBJECT; SIZE OF PUL- LETS' EGGS FROM WHICH RESPECTIVE BIRDS WERE HATCHED, RELATIVE 47 Coefficient of correlation = .30 ± .131 49 51 53 55 57 59 61 50 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 0 68 0 70 0 72 0 74 1 1 22 TABLE 29. MEAN SIZE OF FOURTH YEAR'S PRODUCTION OF BIRDS, SUBJECT; SIZE OF PUL- LETS' EGGS FROM WHICH RESPECTIVE BIRDS WERE HATCHED, RELATIVE Coefficient of correlation = .50 ± .191 47 49 51 53 55 57 59 50 1 1 52 0 54 1 1 2 56 1 1 58 0 60 1 1 62 0 64 1 1 66 0 68 1 1 1102 0 1 7 230 EARL W. BENJAMIN TABLE 30. MEAN SIZE OF LIFE PRODUCTION OF BIRDS, SUBJECT; SIZE OF PULLETS' EGGS FROM WHICH RESPECTIVE BIRDS WERE HATCHED, RELATIVE Coefficient of correlation = .37 =t .065 45 47 49 51 53 55 57 59 61 63 65 46 1 48 1 1 2 2 2 50 1 1 3 1 1 1 52 1 2 1 3 1 1 54 2 1 7 3 1 1 56 2 2 2 1 331 1 58 1 2 4 3 1 2 60 1 1 1 1.1 1 62 2 64 1 1 1 66 68 c 70 72 74 1 13 6 20 10 10 1 8 8 9 15 15 13 6 2 3 0 0 0 0 1 81 TABLE 31. MEAN SIZE OF FIRST YEAR'S PRODUCTION OF BIRDS, SUBJECT; SIZE OF HENS' EGGS FROM WHICH RESPECTIVE BIRDS WERE HATCHED, RELATIVE Coefficient of correlation = .31 ± .065 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 45 47 49 51 53 55 57 59 61 63 65 67 69 1 1 0 0 0 1 1 1 1 2 1 1 1 1 4 3 2 3 8 3 2 325 1 1 17 2 3 2 1 4 2 2 112 20 1 2 2 1 2 4 1 1 1 15 3 2 2 1 1 9 1 1 1 2 5 1 1 1 1 1 1 4 1 1 13 11 17 12 STUDY OF SELECTIONS FOR SIZE, SHAPE, AND COLOR OF HENS' EGGS 231 TABLE 32. MEAN SIZE OP SECOND YEAR'S PRODUCTION OF BIRDS, SUBJECT; SIZE OF HENS' EGGS FROM WHICH RESPECTIVE BIRDS WERE HATCHED, RELATIVE Coefficient of correlation = .46 ± .099 45 47 49 51 53 55 57 59 61 63 65 67 50 1 12 1 5 52 1 1 2 54 1 1 2 56 1 1 1 3 58 212 1 6 60 1 1 1 3 62 1 1 64 1 3 4 66 0 68 1 1 2 70 1 *» 1 29 TABLE 33. MEAN SIZE OF THIRD YEAR'S PRODUCTION OF BIRDS, SUBJECT; SIZE OF HENS' EGGS FROM WHICH RESPECTIVE BIRDS WERE HATCHED, RELATIVE Coefficient of correlation = .65 ± .123 52 1 1 2 54 1 1 56 1 1 2 58 1 1 60 1 12 62 0 64 1 1 66 11 10 45 47 49 51 53 55 57 59 61 63 65 1 1 1 1 1 1 1 1 1 1 232 EARL W. BENJAMIN TABLE 34. MEAN SIZE OF LIFE PRODUCTION OF BIRDS, SUBJECT; SIZE OF HENS' EGGS FROM WHICH RESPECTIVE BIRDS WERE HATCHED, RELATIVE Coefficient of correlation = .34 ± .063 45 47 49 51 53 55 57 59 61 63 65 67 69 71 73 75 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 1 2 2 1 - 1 2 3 4 1 1 2 3 3 5 1 1 1 1 3 1 4 2 1 1 2 I 4 1 2 4 1 1 1 1 1 1 3 1 1 1 1 2 1 1 1 1 1 1 2 2 1 1 1 1 1 0 0 0 0 1 4 10 17 16 16 2 3 5 11 11 9 16 14 3 5 3 3 4 0 0 1 90 TABLE 35. MEAN SHAPE OF FIRST YEAR'-S PRODUCTION OF BIRDS, SUBJECT; SHAPE OF PULLETS' EGGS FROM WHICH RESPECTIVE BIRDS WERE HATCHED, RELATIVE Coefficient of correlation = .39 ± .106 68 69 70 71 72 73 74 75 76 77 78 79 80 64 1 1 63 1 1 2 68 1 1 1 3 70 1 1 2 4 72 2 3 2 1 2 10 74 1 2 11 16 76 1 1 78 1 1 80 1 1 13124 352 2 4 1 0 1 29 STUDY OF SELECTIONS FOR SIZE, SHAPE, AND COLOR OF HENS' EGGS 233 TABLE 36. MEAN SHAPE OF SECOND YEAR'S PRODUCTION OF BIRDS, SUBJECT; SHAPE OP PULLETS' EGGS FROM WHICH RESPECTIVE BIRDS WERE HATCHED, RELATIVE Coefficient of correlation = .23 ± .192 69 70 71 72 73 74 75 76 77 68 1 11 1 4 70 11 11 4 72 1 1 2 74 0 76 1 1 11 TABLE 37. MEAN SHAPE OF LIFE PRODUCTION OF BIRDS, SUBJECT; SHAPE OF PULLETS' EGGS FROM WHICH RESPECTIVE BIRDS WERE HATCHED, RELATIVE Coefficient of correlation = .43 ± .102 68 69 70 71 72 73 74 75 76 77 78 79 80 66 1 1 1 3 68 1 1 70 11 1 12 6 72 2 3211 1 10 74 1 11 11 1 6 76 1 1 78 1 1 80 1 1 29 234 EARL W. BENJAMIN TABLE 38. MEAN SHAPE OF FIRST YEAR'S PRODUCTION OF BIRDS, SUBJECT; SHAPE OF HENS' EGGS FROM WHICH RESPECTIVE BIRDS WERE HATCHED, RELATIVE Coefficient of correlation = .34 =b .083 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 77+ 54 1 56 58 60 62 64 66 1 121 68 11112 1 70 11 11 2 72 1 11 1 2132 1 2 2 74 1 2 1211 76 1 2 1 78 1 1 4 80 1 0323346737 1 0 0 0 0 0 5 7 6 17 8 4 3 1 52 TABLE 39. MEAN SHAPE OF SECOND YEAR'S PRODUCTION OF BIRDS, SUBJECT; SHAPE OF HENS' EGGS FROM WHICH RESPECTIVE BIRDS WERE HATCHED, RELATIVE 67 68 Coefficient of correlation = .47 ± .101 69 70 71 72 73 74 75 76 77 66 1 111 4 68 1 1 70 1 1 1 1 1 5 72 1 1 2 2 6 74 1 2 1 1 1 6 76 1 1 1 1 4 78 1 1 2 1 27 STUDY OF SELECTIONS FOR SIZE, SHAPE, AND COLOR OF 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 69 70 71 72 73 74 75 76 77 ^54 1 1 56 0 58 0 60 0 62 0 64 0 66 1 1 68 1 1 70 1 1 1 1 4 72 1 1 2 74 1 1 1 3 21012 0 2 1 3 12 TABLE 41. MEAN SHAPE OF LIFE- PRODUCTION OF BIRDS, SUBJECT ; SHAPE OF HENS' EGGS FROM WHICH RESPECTIVE BIRDS WERE HATCHED, RELATIVE Coefficient of correlation = .31 ± .084 61 or less 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 77+ 54 1 1 56 0 58 0 60 0 62 0 64 1 1 66 1 11 1 1 5 68 1 1 1 3 70 1111 2 2 3 1 12 72 1 1 1 2 1211 1 2 3 16 74 1 1 3 1 6 76 1 1 2 1 5 78 1 1 1 3 80 1 1 110110.3233 4673 7 4 6 1 53 236 EARL W. BENJAMIN TABLE 42. MEAN COLOR OF FIRST YEAR'S PRODUCTION OF BIRDS, SUBJECT; COLOR OF PULLETS' EGGS FROM WHICH RESPECTIVE BIRDS WERE HATCHED, RELATIVE Coefficient of correlation = — .12 ± .07 1234567 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 3.5-4.0 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 0 0 2 100 TABLE 43. MEAN COLOR OF SECOND YEAR'S PRODUCTION OF BIRDS, SUBJECT; COLOR OF PULLETS' EGGS FROM WHICH RESPECTIVE BIRDS WERE HATCHED, RELATIVE Coefficient of correlation = .002 ± .105 1 234 5 6 7 1.0- 1.5 1.5- 2.0 2.0- 2.5 2.5- 3.0 3.0- 3.5 3.£- 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 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 1 2 1 4 2 2 1 1 1 3 2 1 1 2 1 3 1 1 1 2 1 1 2 1 • 1 - 1 13 16 1 3 5 7 7 3 5 1 3 0 3 1 1 0 0 0 0 0 1 41 STUDY OF SELECTIONS FOR SIZE, SHAPE, AND COLOR OF HENS' EGGS 237 TABLE 44. MEAN COLOR OF THIRD YEAR'S PRODUCTION OF BIRDS, SUBJECT; COLOR OF PULLETS' EGOS FROM WHICH RESPECTIVE BIROS WERE HATCHED, RELATIVE Coefficient of correlation = .57 =t .15 1.6-2.0 1 2.0-2.5 2.5-3.0 2 3.0-3.5 1 1 3.5-4.0 1 1 4.0-4.5 1 4.5-5.0 5.0-5.5 5.5-6.0 1 TABLE 45. MEAN COLOR OF LIFE PRODUCTION OF BIRDS, SUBJECT; COLOR OF PULLETS EGOS FROM WHICH RESPECTIVE BIRDS WERE HATCHED, RELATIVE Coefficient of correlation = — .26 ± .06 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.^4.0 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 0 6.5-7.0 0 7.0-7.5 1 1 2 7.5-8.0 1 1 28 38 20 100 238 EARL W. BENJAMIN TABLE 46. MEAN COLOR OF FIRST YEAR'S PRODUCTION OF BIRDS, SUBJECT; COLOR OF HENS' EGGS FROM WHICH RESPECTIVE BIRDS WERE HATCHED, RELATIVE 1 2 3 Coefficient of correlation = .20 ± .08 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 2 2 4 1 2.0-2.5 1 3 3 2 1 2.5-3.0 5 3 3 3 2 3.0-3.5 1 2 1 1 1 1 3.5-4.0 3 2 1 4.0^.5 1 1 2 2 1 4.5-5.0 1 1 5.0-5.5 1 2 1 5.5-6.0 1 6.0-6.5 6.5-7.0 1 7.0-7.5 7.5-8.0 1 8.0-8.5 8.5-9.0 1 15 15 17 9 4 400000000100001 1 9 10 16 7 6 7 2 4 1 0 1 0 1 0 1 66 TABLE 47. MEAN COLOR OF SECOND YEAR'S PRODUCTION OF BIRDS, SUBJECT; COLOR OF HENS' EGGS FROM WHICH RESPECTIVE BIRDS WERE HATCHED, RELATIVE Coefficient of correlation = .31 db .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 1231 1 2.5-3.0 1 3.0-3.5 2 1 3.5-4.0 2 4.0-4.5 1 1 4.5-5.0 111 1 5.0-5.5 1 1 5.5-6.0 1 6.0-6.5 6.5-7.0 1 7.0-7.5 7.5-8.0 8.0-8.5 8.5-9.0 1 5484230000000 0 1 0 0 0 01 1 2 8 1 3 2 2 4 2 1 0 1 0 0 0 1 28 STUDY OF SELECTIONS FOR SIZE, SHAPE, AND COLOR OF HENS' EGGS 239 TABLE 48. MEAN COLOR OF THIRD YEAR'S PRODUCTION OF BIRDS, SUBJECT; 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 1.0-1.5 1 1 1.5-2.0 1 1 2.0-2.5 1 1 2.5-3.0 1 1 3.0-3.5 0 3.5-4.0 1 1 4.0-4.5 1 1 1 3 4.5-5.0 1 1 5 0-5.5 1 1 5.5-6.0 . 0 6.0-6.5 0 6.5-7.0 0 7.0-7.5 1 1 1141110000000 0 1 0 0 0 01 11 TABLE 49. MEAN COLOR OF LIFE PRODUCTION OF BIRDS, SUBJECT: COLOR OF HENS' EGOS FROM WHICH RESPECTIVE BIRDS WERE HATCHED, RELATIVE Coefficient of correlation = .28 ± .08 1234567 8 9 10 11 12 13 14 15 16 17 18 19 20 1.0-1 5 1 1.5-2 0 1 1 3 1 2.0-2 5 2 4 4 1 2.5-3 0 5 3 3 2 2 3.0-3 5 1 2 2 2 3.5-4 0 3 •2 1 1 4.^4 5 1 1 2 2 1 4.5-5 0 1 1 1 2 5.0-5 5 3 5.5-6 0 6.0-6 5 1 1 6.5-7 0 7.0-7 5 7.5-8 0 1 1 8.0-8 5 8.5-9.0 1 15 15 18 9440000000 0 1 0 0 0 01 1 6 11 15 7 7 7 5 3 0 2 0 0 2 0 1 67 240 EARL W. BENJAMIN TABLE 50. SUMMARY OF CORRELATIONS BETWEEN CHARACTER MEANS FOR PRODUCTION FOR SEPARATE YEARS AND FOR LIFE, SUBJECT, AND CHARACTERS FOR PARENT EGGS INCUBATED FROM PULLETS OR FROM HENS, RELATIVE Character Year of production (means for) Pullets' eggs incubated Hens' eggs incubated Coefficient of correlation r 17 Number of indi- viduals Coefficient of correlation r Er" Number of indi- viduals Size First .40 ±.033 .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 10 Second Third Fourth Life .34±.063 5.4 90 Shape First Second Third Life .39 ±.106 .23 ±.192 ''43'±'.102 3.7 1.2 29 11 .34±.083 .47±.101 .52±.142 .31±.084 4.1 4.7 3.7 3.7 52 27 12 53 4.2 29 Color First Second -.12 ±.07 .002±.105 .57 ±.15 -.25 ±.06 1.7 0.02 3.8 4.3 100 41 9 100 .20±.08 .31±.10 .17±.20 .28±.08 2.5 3.1 0.8 3.5 66 28 11 67 Third Life TABLE 51. SUMMARY OF — - FROM TABLE 50 Year of production Character Hir Pullets' eggs incubated Hens' eggs incubated First Size Shape Color 6.3 3.7 1.7 4.8 4.1 2.5 Second Size 3.6 1.2 0 02 4.6 47 3.1 Shape Color Third feize Shape 23 5.3 3.7 0.8 Color 3.8 Life Size Shape 5.7 4.2 43 5.4 3.7 3.5 Color 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, -p-' 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 life 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 (WEIGHT IN GRAMS) .OP EGGS LAID BY BIRDS, SUBJECT; SIZE OF EGGS FROM WHICH RESPECTIVE BIRDS WERE HATCHED, RELATIVE Coefficient of correlation = .458 db .007 46 48 50 52 54 56 58 60 62 64 66 68 70 72 74 28-30 1 30-32 1 32-34 1 34-36 3 1 36-38 4 6 2 38HIO 3 6 1 40-42 2 8 1 5 1 5 42-44 10 8 3 27 2 2 1 44^6 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 56-58 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 19 70-72 1 13 72-74 j 1 3 74-76 2 1 1 1 1 4 12 10 22 53 167 302 498 614 735 786 694 486 320 274 169 57 22 14 5 3 300 646 376 41 S 585 557 667 2 356 500 811 28 0 5,250 the individual eggs produced by the respective birds hatched! The factor -gj equals, for size, shape, and color, respectively, 65, 20, and 16. This is significant and suggests the same relative degrees of inheritance as are found in other studies in this investigation. 242 EARL 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 EGGS LAID BY BIRDS, SUBJECT; SHAPE OF EGGS FROM WHICH RESPECTIVE BIRDS WERE HATCHED, RELATIVE Coefficient of correlation = .204 ± .01 64 66 68 70 72 74 76 78 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 44 310 196 146 97 80 397 175 211 39 43 355 122 148 21 13 175 59 39 5 4 48 4 10 1 9 3 4 1 9 1 3 1 1 1 1 2 1 1 1 680 247 1,637 796 701 1 0 2 14 46 127 326 624 840 961 707 307 71 17 11 3 1 0 2 1 2 0 2 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 OF SELECTIONS FOR SIZE, SHAPE, AND COLOR OF HENS' EGGS 243 TABLE 54. COLOB OF EGOS LAID BY BIRDS, SUBJECT; COLOR OP EGGS FROM WHICH RESPECTIVE BIRDS WERE HATCHED, RELATIVE Coefficient of correlation = .145 rfc .009 1 2 .3 4 5 6 7 8 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 10 17 143 238 40 182 175 117 10 33 396 298 168 188 206 107 26 16 215 174 173 183 227 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 1 5 18 15 26 2 16 4 5 26 20 19 3 2 7 1 2 21 19 30 7 3 8 1 19 5 10 2 1 6 8 9 11 2 2 1 16 6 2 1 1 1 892 995 791 938 1,050 367 144 190 938 1,405 1,101 686 389 235 119 130 83 86 91 37 39 23 3 1 1 5,367 66-68 62-64 58-60 54-56 50-52 46-48- 42-44- 38-40 34-36 30-32 66-68 62-64 IMi 54-5« 50-52 46-48 42-44 38-40 34-36 58-60 54-56- r I 20 24 28 1 5 9 13 17 21 25 29 2 « 10 14 18 22 28 1 5 9 13 17 21 25 29 2 December January February March April PlG. 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 EARL W. BENJAMIN Relation of eggs incubated 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. Grams Weeks 6 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86 91 96 101 FlG. 19. VARIATION OF SIZE (WEIGHT IN GRAMS), BY WEEKLY AVERAGES, OF EGGS PRO- DUCED BY 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 FlG. 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 EARL 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 line 8224F, one of the largest lines, and by line 3916F, one of the smallest lines. The difficulty of observing the fine differences in size, except by careful measurements, is seen from this figure. Under line 3916F is shown another record of the production of 8882F. 20 24 28 1 5 9 13 17 21 25 29 2 6 10 14 18 22 26 1 5 9 13 17 21 25 29 2 FIG January February March April 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 lines shown in figure 23 are shown also in figure 22. Neither the shape nor the size of STUDY OF SELECTIONS FOR SIZE, SHAPE, AND COLOR OF HENS' EGGS 247 eggs has a large coefficient of variability, and this fact is reflected in the curves and in the photographic record. Shape index 1 Weeks 6 11 16 21 26 31 36 41 46 51 56 61 66 .71 76 81 86 91 % 101 FlG. 22. VARIATION OF SHAPE, BY WEEKLY AVERAGES, OF EGGS PRODUCED BY 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 The color character has a much higher coefficient of variability, 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 EARL W. BENJAMIN FlG. 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, but only twelve eggs for each year could be represented in this group STUDY OF SELECTIONS FOR SIZE, SHAPE, AND COLOR OF HENS' EGGS 249 data previously reviewed, only by the high coefficient of variability and the probability that many abnormal eggs are incubated instead of the normal type for the respective dam. 20 24 28 December 5 9 13 17 21 25 January 2 6 10 14 18 22 26 1 February 9 13 17 21 29 2 April FlG. 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 EARL W. BENJAMIN *•••• ••*• ••••••••••• ::: si : : ::: ::: :: ::;:: : : : :: ::: : : ::::: :::: : :: : ••••• ••••• sssss ::::: ::::: :::::::::: ::::: :: : iSSSS 5SSSS ""I SSSSS SSSSS ! • s s ; : • s ss i sis s sssssssssii VARIATION OF COLOR, BY WEEKLY AVERAGES, OF EGGS PRODUCED BY 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 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 OF SELECTIONS FOR SIZE, SHAPE, AND COLOR OF HENS' EGGS 251 £ I £ g s i rt s o e I § & *o o I X l_^, ^H ^ ^H f 1 40. \ 1.20. Year L it - d : d 4 h 5 h 6th -FlG. 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. PERCENTAGE OP EACH YEAR'S FLOCK BEGINNING TO LAY IN THE RESPECTIVE MONTHS FROM NOVEMBER TO JUNE, INCLUSIVE Month when laying began Percentage of year's flock that began laying in respective months 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 December January 0.3 21.7 29.6 28.2 11.2 9.0 1.1 8.6 28.0 28.4 22.6 9.7 "I.I 0.5 5.6 2.6 2.6 43.6 48.6 2.6 6.2 28.4 46.9 18.5 5.6 33.3 49.9 5.6 February 20.0 80.0 March April . May 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 sufficient number of birds to make the figures reasonably reliable. 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 j^ears 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 slightly. All seasonal effects are eliminated in these studies, the birds being arranged in accordance with the month when they 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 for EARL W. BENJAMIN fleas? for ^ecor/tf Grams //*tt7/ry nrnritsr.f .. . .<>/*fh /yerr^s ps-r>e/,jr+m , 64 - 62 - Ml*^ r 61 - J W^>*-" \ 60 59 - / \ / X «^\(£ 58- 94-) , /^ X ^"(7 57- 56- 56 - (l\SJ "-^**^ zz^ f L°i . 109) T5)_ — . ?&\*^^ & ^*^ 39> C ^^ ^^^ 54- II) --,*' f~ ^^ — • ^ "" "*" ^ 53- jj«J>, — 52. 51 > (\05}** ** ^13^.— Month 1st 2d 3d 4th 5th 6th 7th 8t FlG. 28. MONTHLY VARIATION IN SIZE OF EGGS PRODUCED YEARS The figures in parenthesis designate the number of birds available for Sec one/ years T/?/s& t/e&s? feoc/r/fy t/e&ry f/tfh U£ Grams proc/c/cr /?sioc/tscf proc/tscf — - • ~ • ArtX/tsc* h 9t DURING the respec > h 10th llth A PERIOD OF SIX :tive calculations 5/xfc yecrrs 1 / / \ / L (?) 51) 58- RA / \ ^ w ~ZL "^^^^e 30 630 / V [«> \ '(30) / > / !s^^ • 3i) e3b-^ — ai trr-s r^nT* 31) ?e; / \ / ^~ / • / K9- fl«T ^*" TO JIO) s Is; \ / ^^^ • ^^ ^J-1— -*• " \ S (3) ^f; i *T«. *»y &s «CA 4} (1) *»« 48- -***""^ '$ 4U H( Month 1st 2d 3d 4th 5th 6th 7th 8th 9th 10th llth FlG. 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 FOR 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 34 Month 1st 2d 3d 7th 8th 9th 10th llth FlG. 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 EARL 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 materially different from those for lower producers. Dec. Jan. Feb. March April May June Aug. FlG. 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 and at the end of the litter is observed, as claimed by Fere (1898b) 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 FOR 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 Month 1st llth FlG. 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 life means of the birds. Where slight 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 years T/7/rrf t/ecrrs /E>t/rf/7 i/ears f/ffft years T)th Gth 7th 8th 9th 10th llth FlG. 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 FOR SIZE, SHAPE, AND COLOR OF HENS' EGGS 261 Index 75 65 Month 1st 9th 10th llth FlG. M. 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 Index ** 75 1 2 4 4 7 4 4 2 2 1 1 3 2 3 3 9 2 7 4 1 1 2 3 6 8 7 4 1 1 1 2 4 2 5 4 3 5 2 1 1 1 1 2 5 1 6 7 2 1 3 2 2 1 1 6 4 3 1 1 1 1 2 1 1 2 2 5 3 1 1 1 5 3 3 4 3 3 ' 1 1 1 1 1 1 1 1 1 2 3 8 16 19 24 32 34 33 31 32 21 16 22 5 1 1 1 1 7 19 22 37 53 44 44 31 19 11 7 3 4 302 276 EARL W. BENJAMIN TABLE 66. SIZE OF BIRDS AT AGE OF 12 WEEKS, SUBJECT; SIZE OF EGGS FROM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .20 ± .040 300-320 320-340 340-360 360-380 380-400 400-420 420-440 440-460 460-480 ' 480-500 500-520 520-540 540-560 560-580 580-600 600-620 620-640 640-660 660-680 680-700 700-720 720-740 740-760 760-780 780-800 44 46 48 50 52 54 56 58 60 62 64 66 68 70 1 1 1 2 1 1 2 1 3 3 1 1 2 1 2 2 1 1 1 1 2 2 1 1 1 3 2 1 1 1 1 1 2 1 1 2 2 2 1 1 2 3 1 6 1 2 1 1 1 1 1 1 2 2 3 1 3 2 2 3 5 3 1 1 1 1 1 2 3 2 4 2 3 1 1 8 6 6 1 1 1 1 1 1 1 3 3 5 2 2 1 2 5 2 3 1 2 1 2 1 5 2 3 1 1 1 1 1 1 2 3 4 1 1 3 2 1 1 2 1 1 1 2 1 1 2 2 1 2 3 1 1 2 1 2 1 1 1 3 1 1 1 1 1 1 6 1 12 8 6 13 12 17 12 20 2 19 25 18 15 16 14 7 8 13 6 7 1 2 2 1 7 16 17 32 45 38 36 29 18 11 7 2 3 262 STUDY OF SELECTIONS FOR SIZE, SHAPE, AND COLOR OF HENS' EGGS 277 'ABLE 67. SIZE OF BIRDS AT AGE OF IG^WEEKS, SUBJECT; SIZE OF EGGS FROM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .19 ± .040 360- 400 400- 440 440- 480 480- 520 520- 560 560- 600 600- 640 640- 680 680- 720 720- 760 760- 800 800- 840 &40- 880 880- 920 920- 960 960-1000 1000-1040 1040-1080 1080-1120 1120-1160 1160-1200 1200-1240 1240-1280 44 46 48 50 52 54 56 58 60 62 64 66 68 70 1 1 1 3 1 1 2 1 1 3 2 2 1 1 1 2 3 3 3 1 1 1 2 1 2 1 1 1 1 2 2 1 4 4 1 1 2 1 1 2 1 3 1 2 2 2 2 2 2 2 1 1 2 1 2 4 2 3 2 2 1 3 4 2 2 1 1 1 1 4 5 3 3 3 2 1 2 2 3 5 4 2 1 1 1 2 4 4 3 6 9 1 1 3 7 3 3 2 1 1 1 2 2 1 2 1 2 1 1 1 1 1 1 1 1 1 34 1 3 2 1 1 1 2 1 1 2 1 1 u-^ 1 I 1 7 7 6 13 9 16 12 15 17 17 22 20 30 20 9 8 12 8 4 4 1 1 1 7 16 20 30 42 41 38 25 18 11 6 2 2 259 278 EARL W. BENJAMIN TABLE 68. SIZE OP BIRDS AT AGE OF 20 WEEKS, SUBJECT; SIZE OF EGGS FROM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE 400- 500 500- 600 600- 700 700- 800 800- 900 900-1000 1000-1100 1100-1200 1200-1300 1300-1400 1400-1500 Coefficient of correlation = .18 d= .040 44 46 48 50 52 54 53 58 60 62 64 63 68 70 1 1 1 1 3 3 3 2 1 1 1 3 3 1 4 1 2 1 1 7 3 5 4 5 5 5 6 3 1 1 2 5 9 13 10 10 3 5 1 1 4 5 3 12 8 5 9 1 4 2 1 1 2 5 6 2 8 8 4 2 3 2 2 2 1 6 4 4 1 1 2 1 1 1 2 5 10 17 44 60 54 43 23 2 1 1 8 13 24 27 40 36 39 35 11 12 9 4 2 261 TABLE 69. SIZE OF BIRDS AT AGE OF 24 WEEKS, SUBJECT; SIZE OF EGGS FROM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .15 ± .066 600- 700 700- 800 800- 900 900-1000 1000-1100 1100-1200 1200-1300 1300-1400 1400-1500 1500-1600 1600-1700 1700-1800 1800-1900 46 48 ,50 52 54 56 58 60 62 64 66 68 70 1 1 1 1 1 1 3 1 3 1 1 3 2 2 1 2 3 1 2 1 1 1 1 3 4 7 1 4 1 2 1 1 3 4 4 6 4 7 1 2 1 1 4 2 5 6 2121 1 2 1 2 2 1 3 3 2 1 2 3 1 1 4 8 9 15 20 20 20 22 5 8 6 2 1 2 2 1 10 18 25 30 27 15 5 3 1 1 140 STUDY OF SELECTIONS FOR SIZE, SHAPE, AND COLOR OF HENS' EGGS 279 TABLE 70. SIZE OF BIRDS AT AGE OF 28 WEEKS, SUBJECT; SIZE OF EGGS FROM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .12 ± .039 600- 700 700- 800 800- 900 900-1000 1000-1100 1100-1200 1200-1300 1300-1400 1400-1500 1500-1600 1GOO-1700 1700-1800 1800-1900 1900-2000 2000-2109 2100-2200 2200-2300 44 46 48 50 52 54 56 58 60 62 64 66 68 70 1 1 2 1 1 2 1 1 2 4 1 3 6 2 1 2 1 1 17 3 2 6 3 3 5 2 1 25 122 4 9 10 6 10 6 1 2 53 3 5 4 6 6 8 6 1 4121 47 6 6 5 11 7 3 6 1 3111 51 1 1 4 7 6 6 5 2 3 2 1 38 1 1 2 5 5 2 1 3 20 2 1 1 1 2 1 3 1 1 13 1 2 2 1 2 8 1 1 2 4 1 1 2 0 0 1 1 1 8 14 25 33 47 38 41 40 11 11 9 5 4 287 'ABLE 71. SIZE OF BIRDS AT AGE OF 32 WEEKS, SUBJECT; SIZE OF EGGS FROM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Efficient of correlation = .31 ± .036 700- 800 800- 900 900-1000 1000-1100 1100-1200 1200-1.300 1300-1400 1400-1500 1500-1600 16001700 1700-1800 1800-1900 1900-2000 2000-2100 2100-2200 2200-2300 44 46 48 50 52 54 56 58 eO 62 64 66 68 70 1 1 1 1 121 2 3 1 1 7 1126 1 1 4 6 1 1 7 1 5 9 1 2 2 3 2 2 1 1 1 3375 10 4 2 10 1 2 355 11 10 6 8 1 2 2 2 444 9 5 6 3 2 1 1 1 3 4 8 2 4 2 2 1 1 1 1 1 2 6 2 1 2 2 2 2 1 1 1 1 1 1 1 1 1 2 1 3 1 7 11 23 38 47 55 39 29 15 9 4 1 3 1 1 8 14 26 32 48 41 38 11 11 9 5 4 286 280 EARL W. BENJAMIN TABLE 72. SIZE OF BIRDS AT AGE OF 36 WEEKS, SUBJECT; SIZE OF EGGS FROM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .33 ± .037 . .~J ; ] 44 46 48 50 52 54 56 58 60 62 64 66 68 700- 800 800- 900 900-1000 1000-1100 1100-1200 1200-1300 1300-1400 1400-1500 1500-1600 1600-1700 1700-1800 1800-1900 1900-2000 2000-2100 2100-2200 2200-2300 70 1 1 2 0 2 1 3 1 1 1 1 1 5 2 1 3 3 1 3 1 14 3 6 3 3 4 7 2 1 1 30 3 4 3 7- 7 8 4 1 3 1 1 42 2 5 5 8 9 6 6 6 1 48 1 1 5 5 7 7 4 6 2 3 2 1 2 46 1 1 1 10 6 7 3 1 2 1 1 34 1 3 2 4 1 3 2 16 2 3 4 4 2 3 18 1 2 1 1 1 6 1 1 2 1 1 2 1 1 13 25 28 44 38 41 33 10 11 9 5 3 269 TABLE 73. SIZE OF BIRDS AT AGE OF 40 WEEKS, SUBJECT; SIZE OF EGGS FROM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .28 ± .038 900-1000 1000-1100 1100-1200 1200-1300 1300-1400 1400-1500 1500-1600 1600-1700 1700-1800 1800-1900 1900-2000 2000-2100 2100-2200 2200-2300 2300-2400 46 48 50 52 54 56 58 60 62 64 66 68 70 1 1 1 1 2 2 2 1 1 2 6 3 2 3 18 3 1 6 6 9 6 4 7 1 1 44 3 3 4 6 10 7 10 7 3 4 3 1 61 6 8 3 12 7 10 1 1 2 1 1 52 3 5 6 6 6 5 2 1 2 36 2 5 4 5 3 7 1 1 2 30 3 2 2 1 1 1 2 1 13 2 3 1 6 1 1 0 1 1 2 1 1 7 13 26 32 47 33 40 36 11 9 8 3 4 2G9 STUDY OF SELECTIONS FOR Sizu, SHAPE, AND COLOR OF HENS' EGGS 281 TABLE 74. SIZE OF BIRDS AT AGE OF 44 WEEKS, SUBJECT; SIZE OF EGGS FROM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .34 ± .035 1000-1100 1100-1200 1200-1300 1300-1400 1400-1500 1500-1600 1600-1700 1700-1800 1800-1900 1900-2000 2000-2100 2100-2200 46 48 50 52 54 55 58 60 62 64 66 68 70 1 1 2 1 2 1 1 5 3 1 4 4 3 2 2 4 1 24 1 3 5 11 9 3 4 6 1 43 3 3 8 4 15 8 8 4 3 1 1 1 59 3 4 4 9 8 9 5 1 3 1 1 2 50 2 2 6 5 3 8 7 1 3 2 1 40 1 1 2 8 1 6 3 1 1 1 25 2 2 1 1 2 2 10 1 1 1 3 0 1 1 2 7 12 25 32 46 34 36 36 11 9 7 4 4 263 TABLE 75. SIZE OF BIRDS AT AGE OF 48 WEEKS, SUBJECT; SIZE OF EGGS FROM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .27 ± .039 900-1000 1000-1100 1100-1200 1200-1300 1300-1400 1400-1500 1500-1600 1600-1700 1700-1800 1800-1900 1900-2000 2000-2100 46 48 50 52 54 58 58 60 62 64 66 68 70 1 1 1 1 1 1 4 1 1 5 2 2 1 3 1 16 4 6 2 11 6 4 5 2 40 2 5 12 7 5 9 3 4 2 1 2 52 2 6 5 6 12 6 7 7 2 2 1 56 3 2 2 10 7 5 9 1 1 2 1 43 4 1 5 6 3 1 3 1 24 1 3 2 1 6 2 15 1 1 1 3 2 2 1 1 2 7 12 24 31 45 33 36 35 11 9 7 4 4 258 282 EARL W. BENJAMIN TABLE 76. SIZE OF BIRDS AT AGE OF 52 WEEKS, SUBJECT; SIZE OF EGGS FROM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .25 ± .039 900-1000 1000-1100 1100-1200 1200-1300 1300-1400 1400-1500 1500-1600 1600-1700 1700-1800 1800-1900 1900-2000 2000-2100 2100-2200 46 48 50 52 54 58 58 60 62 64 65 68 70 1 1 3 2 5 1 1 4 3 1 1 3 4 1 1 20 4 2 8 5 5 7 2 3 1 1 38 1 4 8 3 22 8 4 6 1 1111 61 5 4 10 11 9 7 8 2 2111 61 3 1 2 6 6 7 4 1 2 1 33 3 1 3 4 3 2 1 1 18 2 2 2 3 4 2 2 1 18 0 0 1 1 2 1 1 6 13 22 32 48 34 33 34 11 9 6 3 4 258 TABLE 77. SIZE OF BIRDS AT AGE OF 58 WEEKS, SUBJECT; SIZE OF EGGS FROM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .23 ± .039 700- 800 800- 900 900-1000 1000-1100 1100-1200 1200-1300 1300-1400 1400-1500 1500-1600 1600-1700 1700-1800 1800-1900 1900-2000 2000-2100 2100-2200 46 48 50 52 54 56 58 60 62 64 66 68 70 1 1 0 0 5 1 1 2 9 2 1 1 3 6 5 2 3 1 24 4 2 6 11 7 5 4 6 1 1 1 48 6 3 4 15 7 10 5 2 2. 1 2 57 2 5 10 10 3 4 9 1 1 1 46 1 • 1 1 8 7 9 4 1 2 1 1 3G 1 2 7 2 1 1 2 1 17 1 2 3 2 2 2 1 13 1 3 4 0 0 1 1 1 3 6 13 22 32 48 34 86 34 11 9 6 3 4 258 STUDY OF SELECTIONS FOR SIZE, SHAPE, AND COLOR OF HENS' EGGS 283 TABLE 78. SIZE OF BIRDS AT AGE OP 30 WEEKS, SUBJECT; SIZE OP EGGS FROM WHICH RESPECTIVE CHICKS WERE HATCEHD, RELATIVE Coefficient of cor relation = .37 .it .037 45 48 50 52 54 56 53 60 62 61 65 63 70 700- 800 800- 900 900-1000 1000-1100 1100-1200 1200-1300 1300-1400 1400-1500 1500-1600- 1303-1700 1700-1800 1800-1900 1900-2000 2000-2100 2100-2200 2200-2300 1 1 1 1 2 1 3 6 1 1 8 3 2 3 5 3 1 2 4 2 25 2 1 3 7 8 2 5 3 1 32 1 2 4 5 13 9 4 5 1 2 2 48 5 3 5 6 8 9 8 3 1 48 1 2 5 9 2 6 5 3 2 35 2 1 5 7 6 3 1 1 26 2 3 3 1 212 1 15 1 1 1 2 3 1 9 1 1 1 1 0 1 1 6 13 22 32 47 34 36 32 11 9 6 2 4 234 ABLE 79. SIZE OF BIRDS AT AGE OF 64 WEEKS, SUBJECT; SIZE OP EGGS FROM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .40 =fc .036 43 48 50 52 54 56 53 60 62 64 66 68 70 800- 900 900-1000 1000-1100 1100-1200 1200-1300 1300-1400 1400-1500 1500-1600 1600-1700 1700-1800 1800-1900 1900-2000 2000-2100 2100-2200 1 1 2 1 1 2 3 2 5 1 1 3 2 5 1 1 3 1 18 4 3 3 8 9 7 3 4 1 1 1 44 1 2 6 6 13 8 10 7 2 4 1 60 5 3 5 9 6 6 4 2121 44 2 1 3 4 6 7 5 1 1 30 3 4 3 5 4 122 24 2 2 2 2 1 9 1 2 3 3 9 0 1 1 1 3 1 1 6 13 20 31 47 34 36 32 11 9 6 2 4 251 284 EARL W. BENJAMIN TABLE 80. SIZE OF BIRDS AT AGE OF 68 WEEKS, SUBJECT; SIZE OF EGGS FROM WHICH) RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .30 ± .039 46 48 50 52 54 56 58 60 62 64 66 68 70 800- 900 900-1000 1000-1100 1100-1200 1200-1300 1300-1400 1400-1500 1500-1600 1600-1700 1700-1800 1800-1900 1900-2000 2000-2100 2100-2200 2200-2300 2300-2400 1 1 2 2 4 1 1 1 2 9 2 2 3 2 2 2 4 1 1 19 3 1 5 5 12 3 4 4 1 38 1 1 3 8 9 6 3 3 3 2 1 40 2 4 7 4 7 6 3 1 3211 41 4 1 5 9 4 5 6 3 1 1 39 2 2 6 8 8 4 1 1 1 33 1 2 4 4 1 1 2 15 1 1 2 1 1 1 1 1 1 1 7 0 0 1 1 1 1 6 13 21 31 47 33 36 30 11 8 2 4 248 TABLE 81. SIZE OF BIRDS AT AGE OF 72 WEEKS, SUBJECT; SIZE OF EGGS FROM WHICH RESPECTIVE CHICKS WERS HATCHED, RELATIVE 'Coefficient of correlation = .29 ± .040 800- 900 900-1000 1000-1100 1100-1200 1200-1300 1300-1400 1400-1500 1500-1600 1600-1700 1700-1800 1800-1900 1900-2000 2000-2100 2100-2200 2200-2300 2300-2400 2400-2500 46 48 50 52_54 55 58 60 62 64 66 68 70 1 1 1 1 2 2 1 3 3 6 4 1 2 16 1 1 3 1 6 2 4 1 1 1 21 2 2 6 5 7 7 7 4 2 1112 47 3 4 8 9 7 6 4 2 1 44 3 6 8 3 7 10 4 3 1 45 2 4 6 6 4 2 1 2 1 2 30 1 4 2 4 3 6 1 21 1 2 2 2 1 8 1 1 2 1 1 1 1 0 0 1 1 2 6 13 20 30 46 33 34 30 11 9 6 2 4 244 STUDY OF SELECTIONS FOR SIZE, SHAPE, AND COLOR OF HENS' EGGS 285 TABLE 82. SIZE OF BIRDS AT AGE OF 76 WEEKS, SUBJECT; SIZE OF EGOS FROM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .26 =b .043 900-1000 1000-1100 1100-1200 1200-1300 1300-1400 1400-1500 1500-1600 1600-1700 1700-1800 1800-1900 1900-2000 2000-2100 2100-2200 2200-2300 2300-2400 2400-2500 2500-2600 2600-2700 46 48 50 52 54 56 58 60 62 64 66 68 70 1 * 1 2 2 1 1 4 1 1 1 3 1 4 5 2 2 1 1 1 17 3 2 5 3 10 6 5 3 1 1 1 40 2 4 3 8 4 4 10 7 1 2 45 2 4 4 7 6 4 1 2 1 31 1 2 3 6 3 3 4 3 2 1 28 1 ' 5 3 5 2 2 1 2 1 1 23 2 3 1 2 4 1 13 1 3 2 1 7 1 1 2 2 2 4 1 1 1 1 2 0 0 1 1 6 11 17 2J 40 32 33 28 10 9 6 2 3 223 TABLE 83. SIZE OF BIRDS AT AGE OF 80 WEEKS, SUBJECT; SIZE OF EGGS FRDM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .24 ± .048 900-1000 1000-1100 1100-1200 1200-1300 1300-1400 1400-1500 1500-1600 1600-1700 1700-1800 1800-1900 1900-2000 2000-2100 2100-2200 2200-2300 2300-2400 2400-2500 2500-2600 46 48 50 52 54 56 58 60 62 64 66 68" 70 1 1 1 2 3 1 2 1 4 1 4 2 2 2 1 1 1 1 15 2 2 3 9 2 7 6 1 1 1 1 35 1 2 1 4 4 5 5 5 1 28 1 1 2 2 5 4 2 1 1 19 2 2 5 1 4 2 3 1 20 1 5 4 5 2 21 1 21 1 2 1 2 4 3 1 14 1 3 1 1 6 2 2 1 5 2 2 4 1 i 1 1 1 0 1 1 5 6 12 20 32 24 27 24 10 8 5 2 3 178 286 EARL W. BENJAMIN TABLE 84. SIZE OF BIRDS AT AGE OF 84 WEEKS, SUBJECT; SIZE OF EGGS FROM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .33 db .054 900-1000 1000-1100 1100-1200 1200-1300 1300-1400 1400-1500 1500-1600 1600-1700 1700-1800 1800-1900 1900-2000 2000-2100 2100-2200 2200-2300 2300-2400 2400-2500 46 48 50 52 54 56 58 60 62 64 66 68 70 1 2 3 1 1 1 3 1 2 1 1 1 233 3 4 3 1 2 1 1 2 4 5 1 4 1 1 1 2 1 3 1 3 1 1 2 3 2 2 3 1 3 1 2 3 1 2 21 1 3 5 1 2 1 2 1 1 1 1 1 1 1 1 1 1 3 5 7 13 24 22 15 17 7 6 3 2 1 1 0 2 4 11 19 22 13 16 13 14 5 2 1 0 2 125 TABLE 85. SIZE OF BIRDS AT AGE OF 88 WEEKS, SUBJECT; SIZE OF EGGS FROM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .30 d= .057 46 48 50 52 54 56 58 60 62 64 66 68 70 900-1000 1000-1100 1100-1200 1200-1300 1300-1400 1400-1500 1500-1600 1600-1700 1700-1800 1800-1900 1900-2000 2000-2100 2100-2200 2200-2300 2300-2400 2400-2500 2500-2600 2600-2700 1 1 0 1 1 1 1 2 2 1 1 1 5 1 2 2 3 1 1 1 11 1324 3 6 1 2 1 1 24 3 1 3 3 3 2 1 1 17 1 3 2 2 2 3 1 2 16 4 5 2 11 1 1 1 3 2 1 9 1 1 3 1 1 2 1 1 11 1 1 1 2 1 4 0 1 1 0 1 1 2 5 8 12 20 19 14 16 8 5 4 1 115 ITUDY OF SELECTIONS FOR SIZE, SHAPE, AND COLOR OF HENS' EGGS 287 TABLE 86. SIZE OF BIRDS AT AGE OF 92 WEEKS, SUBJECT; SIZE OF EGGS FROM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .30 ± .055 46 48 50 52 54 56 58 60 62 64 66 68 70 1200-1300 1300-1400 1400-1500 1500-1600 1600-1700 1700-1800 1800-1900 1900-2000 2000-2100 2100-2200 2200-2300 2300-2400 2400-2500 2500-2600 1 1 2 2 1 2 1 6 1 1 1 1 5 2 2 1 1 15 1 2 3 7 4 3 5 1 26 1 1 2 2 3 1 2 2 14 1 2 3 4 4 2 3 1 2 1 23 1 3 2 2 1 1 10 1 2 2 1 1 • 1 1 9 1 3 1 2 1 8 1 1 1 1 4 1 1 1 3 0 1 1 2 1 1 3 5 7 12 23 20 15 17 8 6 4 2 1 123 TABLE 87. SIZE OF BIRDS AT AGE OF 96 WEEKS, SUBJECT; SIZE OF EGGS FROM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .40 ± .051 1100-1200 1200-1300 1300-1400 1400-1500 1500-1600 1600-1700 1700-1800 1800-1900 1900-2000 2000-2100 2100-2200 2200-2300 2300-2400 46 48 50 52 54 58 58 60 62 64 66 68 70 1 1 1 1 1 1 3 3 246 2 4 2 2 3 2 1 2 1 2 5 3 4 4 1 1 3 3 3 2 4 2 3 1 1 3 5 1 1 1 3 4 2 2 1 1 1 1 1 2 1 1 2 1 1 1 1 356 12 2320 15 17 86421 1 1 14 23 23 23 "11 7 7 5 3 1 3 122 288 EARL W. BENJAMIN TABLE 88. SIZE OF BIRDS AT AGE OF 100 WEEKS, SUBJECT; SIZE OF EGGS FROM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .35 ± .055 1100-1200 1200-1300 1300-1400 1400-1500 1500-1600 1600-1700 1700-1800 1800-1900 1900-2000 2000-2100 2100-2200 2200-2300 2300-2400 2400-2500 46 48 50 52 54 56 58 60 62 64 66 68 70 1 1 1 2 1 1 1 2 1 2 3 1 1 3 1 1313 7 5 2 1 2 1 1 1 2 3 2 5 3 1 2 1 1 3 1 2 3 2 2 3 3 2 3 2 2 1 2 1 1 1 1 1 1 t 1 1 2 1 1 1 1 2 8 12 26 21 12 13 8 5 4 2 1 0 1 3 5 6 11 22 17 15 15 8 6 4 2 1 115 TABLE 89. SIZE OF BIRDS AT AGE OF 10 1 WEEKS, SUBJECT; SIZE OF EGG3 FROM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .32 ± .057 46 48 50 52 54 56 58 60 62 64 66 68 70 1000-1100 1100-1200 1200-1300 1300-1400 1400-1500 1500-1600 1600-1700 1700-1800 1800-1900 1900-2000 2000-2100 2100-2200 2200-2300 1 1 1 1 1 1 4 1 3 2 1 3 1 11 1 1 1 5 1 2 1 12 1214 3 5 2 1 1 1 1 22 1 2 3 1 2 5 1 1 16 1 1 2 2 1 2 3 2 1 1 16 1 4 4 3 1 2 1 16 1 1 1 3 1 1 1 1 4 1 2 1 4 2 2 1 1 2 3 5 6 11 21 17 14 15 8 6 4 2 1 113 STUDY OF SELECTIONS FOR SIZE, SHAPE, AND COLOR OF HENS' EGGS 289 TABLE 90. SIZE OF BIRDS AT AGE OF 108 WEEKS, SUBJECT; SIZE OF EGGS FBOM WHICH RESPECTIVE CHICKS WEBB HATCHED, RELATIVE Coefficient of correlation = .34 =b .056 46 48 50 52 54 56 58 60 62 64 66 68 70 1000-1100 1100-1200 1200-1300 1300-1400 1400-1500 1500-1600 1600-1700 1700-1800 1800-1900 1900-2000 2000-2100 2100-2200 2200-2300 2300-2400 1 i 2 1 2 1 2 7 2 3 1 1 1 1 3 1 1 2224 3 2 1 1 12141 1 3 3 2 1 1 2 4 2 2 2 1 1 2 1 4 1 1 2 1 1 1 3 1 2 1 1 1 1 2 1 1 1 1 1 3 5 6 11 21 17 14 15 642 2 4 7 18 17 20 14 13 9 4 1 3 0 1 113 TABLE 91. SIZE OF BIRDS AT AGE OF 112 WEEKS, SUBJECT; SIZE OF EGGS FROM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .25 ± .060 900-1000 1000-1100 1100-1200 1200-1300 1300-1400 1400-1500 1500-1600 1600-1700 1700-1800 1800-1900 1900-2000 2000-2100 2100-2200 2200-2300 2300-2400 46 48 50 52 54 53 58 60 62 64 65 68 70 1 1 1 1 1 1 3 5 5 1 1 3 1 1 1 1 12246 1 2 3 1 2 11112 3 3 4 121 1 3 1 3 1 11 1 2 4 3 1 1 2 3 1 2 2 1 1 1 1 1 1 1 1 1 1 7 18 24 20 12 11 10 4 0 2 0 1 3 5 6 11 21 16 14 15 8 6 4 2 1 112 290 EARL W. BENJAMIN TABLE 92. SIZE OP BIRDS AT AGE OF 116 WEEKS, SUBJECT; SIZE OF EGGS FROM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .28 ± .059 46 48 50 52 54 56 58 60 62 64 66 68 70 1000-1100 1100-1200 1200-1300 1300-1400 1400-1500 1500-1600 1600-1700 1700-1800 1800-1900 1900-2000 2000-2100 2100-2200 2200-2300 2300-2400 2400-2500 1 1 2 1 1 1 1 4 1 1 2 4 1 2 3 3 2 2 1 1 1 16 1 3 1 3 1 3 2 14 2113 9 3 3 2 2 23 1 2 2 1 4 2 2 1 15 1 3 1 1 1 1 8 1 2 2 1 1 1 1 9 1 1 2 3 2 1 10 0 1 1 2 0 1 1 1 1 3 5 11 21 15 14 15 6421 112 TABLE 93. SIZE OF BIRDS AT AGB OF 120 WEEKS, SUBJECT; SIZE OF EGGS FROM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .29 ± .059 46 48 50 52 54 53 58 60 62 64 63 68 70 1000-1100 1100-1200 1200-1300 1300-1400 1400-1500 1500-1600 1600-1700 1700-1800 1800-1900 1900-2000 2000-2100 2100-2200 2200-2300 2300-2400 1 2 1 1 3 1 1 1 1 1 1 2 1 3 2 2 3 1 2 { i 1 2249 5 2 4 1 3 4 1 2 5 1 2 1 1 1 1 2 1 1 1 2 2 1 1 1 3 1 1 1 1 1 1 1 1 3 5 6 10 21 15 13 14 8 6 4 2 1 1 3 7 8 14 30 20 6 6 6 3 1 2 1 108 STUDY OF SELECTIONS FOR SIZE, SHAPE, AND COLOR OF HENS' EGGS 291 TABLE 94. SIZE OF BIRDS AT AGE OF 124 WEEKS, SUBJECT; SIZE OF EGOS FBOM WHICH RESPECTIVE CHICKS WEBB HATCHED, RELATIVE Coefficient of correlation = .41 ± .054 1100-1200 1200-1300 1300-1400 1400-1500 1500-1600 1300-1700 1700-1800 1800-1900 1900-2000 2000-2100 2100-2200 2200-2300 46 48 50 52 54 53 58 60 62 G4 66 68 70 2 , 3 2 1 1 4 232 1 1 1 1 1 12 1 1 1 5 1 5 1 1 16 1 2 6 3 1 2 1 2 1 19 1 5 2 6 4 4 2 1 25 3 3 3 1 2 1 13 1 1 2 2 1 1 8 1 1 1 1 4 1 1 1 1 2 2 2 3 5 6 10 21 15 13 15 8 6 4 2 1 109 TABLE 95. SIZE OF BIRDS AT AGE OF 128 WEEKS, SUBJECT; SIZE OF EGGS FROM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .33 db .069 45 47 49 51 53 55 57 59 61 63 65 67 1200-1300 1300-1400 1400-1500 1500-1600 1600-1700 1700-1800 1800-1900 1900-2000 2000-2100 2100-2200 2200-2300 1 1 2 2 1 2 3 2 1 1 3122 1 4 2 1 1 1 1 3 2 1 1 1 1 3 3 1 2 1 1 3 2 1 1 1 2 1 1 1 1 1 1 1 1 1 1 2455 13 9 12 9744 7 9 16 11 11 6 1 7 4 2 1 75 292 EARL W. BENJAMIN TABLE 96. SIZE OF BIRDS AT AGE OF 132 WEEKS, SUBJECT; SIZE OF EGGS FROM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .42 ± .074 1100-1200 1200-1300 1300-1400 1400-1500 1500-1600 1600-1700 1700-1800 1800-1900 1900-2000 2000-2100 2100-2200 2200-2300 2300-2400 45 47 49 51 53 55 57 59 61 63 65 1 1 2 2 1 2 1 1 1 1 1 1 1 1 2 3 2 3 2 1 1 3 1 2 1 4 1 1 1 1 1 1 1 1 2 1 1 1 1 1432 11 797444 1 4 -7 4 11 7 9 4 2 4 2 0 1 56 TABLE 97. SIZE OF BIRDS AT AGE OF 136 WEEKS, SUBJECT; SIZE OF EGGS FROM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .44 ± .077 1000-1100 1100-1200 1200-1300 1300-1400 1400-1500 1500-1600 1600-1700 1700-1800 1800-1900 1900-2000 2000-2100 2100-2200 2200-2300 2300-2400 45 47 49 51 53 55 57 59 61 63 65 " ] 1 1 ] 1 1 ] [ [ [ ' 1 1 1 1 1 1 1 1 ] L 4 1 1 1 1 1 1 2 2 1 1 1 1 1 1 1 1 2 1 2 1 1 1 1 1 1 1 1 24428677344 51 STUDY OF SELECTIONS FOR SIZE, SHAPE, AND COLOR OF HENS' EGGS 293 TABLE 98. SIZE OF BIRDS AT AGE OF 140 WEEKS, SUBJECT; SIZE OF EGGS FBOM WHICH RESPECTIVE CHICKS WEBB HATCHED, RELATIVE Coefficient of correlation = .41 ± .071 1100-1200 1200-1300 1300-1400 1400-1500 1500-1600 1600-1700 1700-1800 1800-1900 1900-2000 2000-2100 2100-2200 2200-2300 2300-2400 2400-2500 2500-2600 45 47 49 51 53 55 57 59 61 63 65 1 1 1 2 2 1 1 2 2 1 2 1 2 2 1 1 161 3 1 1 1 3 1 1 ' 1 1 1 3 1 2 1 2 1 1 1 1 1 1 1 1 2443 11 6 11 8544 1 0 2 6 7 6 13 8 6 5 2 4 0 1 1 62 TABLE 99. SIZE OF BIRDS AT AGE OF 144 WEEKS, SUBJECT; SIZE OF EGGS FBOM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .44 ± .074 1100-1200 1200-1300 1300-1400 1400-1500 1500-1600 1600-1700 1700-1800 1800-1900 1900-2000 2000-2100 2100-2200 2200-2300 2300-2400 2400-2oOO 2500-2600 45 47 49 51 53 . 55 57 59 61 63 65 1 1 1 1 1 1 1 221 2 2 2 1 12 11 2 2 1 1 2 3 1 1 1 1 1 2 1 1 1 1 1 1 2343 10 4 11 8324 1 3 1 2 12 7 7 6 4 4 3 2 1 0 1 54 294 EARL W. BENJAMIN TABLE 100. SIZE OF BIRDS AT AGE OF 148 WEEKS, SUBJECT; SIZE OF EGGS FROM WHICH RESPECTIVE CHICKS WEKE HATCHED, RELATIVE Coefficient of correlation = .49 ± .070 45 47 49 51 53 55 57 59 61 63 65 , 1200-1300 1300-1400 1400-1500 1500-1600 1600-1700 1700-1800 1800-1900 1900-2000 2000-2100 2100-2200 2200-2300 2300-2400 2400-2500 2500-2600 2600-2700 2700-2800 2 1 1 1 21 2 2 2 1 3 4 1 3 1 1 2 1 1 1 2 1 1 2 3 1 2 1 1 1 1 1 1 1 1 1 2 3 4 3 10 4 11 324 2 3 9 14 5 4 6 4 4 1 1 0 0 0 0 1 54 TABLE 101. SIZE OF BIRDS AT AGE OF 152 WEEKS, SUBJECT; SIZE OF EGGS FROM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .52 ± .068 1200-1300 1300-1400 1400-1500 1500-1600 16PO-1700 1700-1800 1800-1900 1900-2000 2000-2100 2100-2200 2200-2300 45 47 49 51 53 55 57 59 61 63 65 1 2 1 1 1 4 1 1 1 1 2 112 2 2 1 11314 1 2 2 2 1 1 1 2 1 1 1 1 1 33394 11 83 1 4 9 11 13 2 5 3 1 2 1 52 STUDY OF SELECTIONS FOR SIZE, SHAPE-,. A&i COLOR" ok IJiiis! .feas 295 TABLE 102. SIZE OF BIRDS AT AGE OP 156 WEEKS, SUBJECT; SIZE OF EGOS FROM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .50 =t .078 45 47 49 51 53 55 57 59 61 63 65 1100-1200 1200-1300 1300-1400 1400-1500 1500-1600 1600-1700 1700-1800 1800-1900 1900-2000 2000-2100 2100-2200 1 1 1 21111 1 3111 2 1 122 2 1 1 3 1 2 1 1 1 1 1 1 1 1 233373 5323 1 2 8 7 10 6 4 3 1 1 1 42 TABLE 103. SIZE OF BIRDS AT AGE OF 160 WEEKS, SUBJECT; SIZE OF EGGS FROM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .48 ± .072 45 47 49 51 53 55 57 59 61 63 65 1300-1400 1400-1500 1500-1600 1600-1700 1700-1800 1800-1900 1900-2000 2000-2100 2100-2200 2200-2300 1 1 1 1 1 1 1 3 1 1 1 1 1 2 2 3 1 1 1 1 1 3 4 1 1 3 1 1 1 % ;- 1 2 1 1 1 1 1 1 1 233394 11 8324 5 8 9 12 5 3 4 3 0 3 52 296 W. BENJAMIN TABLE 104. SIZE OF BIRDS AT AGE OF 164 WEEKS, SUBJECT; SIZE OF EGOS FROM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .43 ± .078 1200-1300 1300-1400 1400-1500 1500-1600 1600-1700 1700-1800 1800-1900 1900-2000 2000-2100 2100-2200 2200-2300 2300-2400 2400-2500 2500-2600 45 47 49 51 53 55 57 59 61 63 65 1 1 1 1 1 1 1 1 2 1 2 1 2 1 1 1 2 1 1 1 3 2 1 2 2 1 1 2 1 2 2 1 1 1 1 1 1 1 2 3 3 2 8 4 11 324 1 4 6 8 11 5 4 6 1 2 1 0 0 1 50 TABLE 105. SIZE OF BIRDS AT AGE OF 168 WEEKS, SUBJECT; SIZE OF EGGS FROM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .50 ± .072 45 47 49 51 53 55 57 59 61 63 65 1100-1200 1200-1300 1300-1400 1400-1500 1500-1600 1600-1700 1700-1800 1800-1900 1900-2000 2000-2100 2100-2200 2200-2300 1 1 111 2 1 2 1 1 2 23 1 1 1 2 2 2 1 3 3 1 1 3 2 1 1 1 1 1 1 1 233284 11 7324 1 0 1 10 10 6 8 6 3 1 1 2 49 STUDY OF SELECTIONS FOR SIZE, SHAPE, AND COLOR OF HENS' EGGS 297 TABLE 103. SIZE OF BIRDS AT AGE OP 172 WEEKS, SUBJECT; SIZE OF Eoos FBOM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .52 rh .070 1200-1300 1300-1400 1400-1500 1500-1600 1600-1700 1700-1800 1800-1900 1900-2000 2000-2100 2100-2200 2200-2300 2300-2400 45 47 49 51 53 55 57 59 61 63 65 1 1 2 1 1 1 1 2 3 1 1 1112 2 2 1 .1 1 1 2 3 2 1 1 1 2 2 4 1 1 1 1 233284 11 8324 2 6 7 10 2 10 5 5 1 0 1 1 50 TABLE 107. SIZE OF BIRDS AT AGE OF 176 WEEKS, SUBJECT; SIZE OF EGGS FROM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .44 ± .082 1000-1100 1100-1200 1200-1300 1300-1400 1400-1500 1500-1600 1600-1700 1700-1800 1800-1900 1900-2000 2000-2100 45 47 49 51 53 55 57 59 61 63 65 1 1 * . 1 1 1 1 2 1 2 1 1 1 1 1 1 2 2 1 1 1 2 1 1 2 1 2 1 1 1 2 2 1 1 1 1 23326488224 44 298 EARL W. BENJAMIN TABLE 108. SIZE OF BIRDS AT AGE OP 180 WEEKS, SUBJECT; SIZE OF EGGS FBOM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .37 ± .108 1000-1100 1100-1200 1200-1300 1300-1400 1400-1500 1500-1600 1600-1700 1700-1800 1800-1900 1900-2000 45 47 49 51 53 55 57 59 61 83 65 1 1 1 2 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 1 1 1 2 1 22324155023 20 TABLE 109. SIZE OF BIRDS AT AGE OF 184 WEEKS, SUBJECT; SIZE OF EGGS FROM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .52 =fc .085 1100-1200 1200-1300 1300-1400 1400-1500 1500-1600 1600-1700 1700-1800 1800- 1900 1900-2000 2000-2100 2100-2200 2200-2300 45 47 49 51 53 55 57 61 63 65 1 1 1 1 1 1 1 2 1 1 1 3 1 1 1 3 1 1 3 1 1 1 1 1 1 1 1 22225287022 1 0 2 3 3 8 5 5 3 1 2 1 34 STUDY OF SELECTIONS FOR SIZE, SHAPE, AND COLOR OF HENS' EGGS 299 TABLE 110. SIZE OF BIRDS AT AGE OF 188 WEEKS, SUBJECT; SIZE OF EGGS FROM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .60 ± .099 45 47 49 51 53 55 57 59 1300-1400 1 1 2 1400-1500 0 1500-1600 1 1 1600-1700 1 1 2 1700-1800 1 2 1800-1900 1 2 4 1900-2000 1 2000-2100 1 2 2100-2200 1 1 2 2200-2300 1 2 2300-2400 1 12265 19 TABLE 111. SIZE OF BIRDS AT AGE OF 192 WEEKS, SUBJECT; SIZE OF EGGS FROM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .59 ± .079 45 47 49 51 53 55 57 59 61 63 1200-1300 1300-1400 1400-1500 1500-1600 1600-1700 1700-1800 1800-1900 1900-2000 2000-2100 2100-2200 2200-2300 2300-2400 2400-2500 1 2 1 1 2 2 3 1 3 1 1 1 1 1 1 1 1 1 1 2 1 1 1 2222528701 1 0 2 1 3 5 6 3 a 4 1 1 1 31 300 EARL W. BENJAMIN TABLE 112. SIZE OF BIRDS AT AGE OP 196 WEEKS, SUBJECT; SIZE OF EGGS FROM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .48 ± .093 45 47 49 51 53 55 57 59 61 63 1200-1300 1 1 1300-1400 0 1400-1500 1 1 2 1500-1600 2 1 2 5 1600-1700 1 1 1 3 1700-1800 1 1 2 1 5 1800-1900 1 1 1 3 1900-2000 1 2 2 1 6 2000-2100 1 2 3 2100-2200 1 1 2 2200-2300 0 2300-2400 0 2400-2500 0 2500-2600 0 2600-2700 1 1 222252 7 0 1 31 TABLE 113. SIZE OF BIRDS AT AGE OF 200 WEEKS, SUBJECT; SIZE OF EGGS FROM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .56 db .084 45 47 49 51 53 55 57 59 61 63 1000-1100 1 1 1100-1200 0 1200-1300 0 1300-1400 1 1 1400-1500 1 1 2 1500-1600 1 1 2 4 1600-1700 1 1 1 13 7 1700-1800 1 1 1800-1900 1 2 2 5 1900-2000 1 211 5 2000-2100 1 1 2100-2200 1 1 2200-2300 1 1 2300-2400 1 1 2222527701 30 STUDY OF SELECTIONS FOR SIZE, SHAPE, AND COLOR OF HENS' EGGS 301 TABLE 114. SIZE OF BIRDS AT AGE OP 204 WEEKS, SUBJECT; SIZE OP EGGS PBOM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .66 ± .068 45 47 49 51 53 55 57 61 63 TABLE 115. 1100-1200 1 1 1200-1300 0 1300-1400 1 1 2 1400-1500 1 1 1500-1600 11 2 1 5 1600-1700 2 2 1 2 2 9 1700-1800 2 1 3 1800-1900 2 2 1900-2000 1 3 4 2000-2100 1 1 2 2100-2200 1 1 2200-2300 1 1 .222252 8 701 31 . SIZE OP BIRDS AT AGE OP 208 WEEKS, SUBJECT; SIZE OP EGOS FROM WHICH RESPECTIVE CHICKS WERE HATCHED , RELATIVE Coefficient of correlation = .49 ± .092 45 47 49 51 53 55 57 59 61 63 1100-1200 1 1 1200-1300 1 1 1300-1400 0 1400-1500 0 1500-1600 1 2 1 1 5 1600-1700 2 2 2 3 9 1700-1800 1 1 2 1 5 1800-1900 1 1 2 1900-2000 1 1 2 2 1 7 2000-2100 0 2100-2200 0 2200-2300 0 2300-2400 0 2400-2500 1 1 2222528701 31 302 EARL W. BENJAMIN TABLE 116. SIZE OF BIRDS AT AGE OF 212 WEEKS, SUBJECT; SIZE OF EGGS FROM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .68 ± .085 45 47 49 51 53 55 57 59 61 63 1100-1200 1 1 1200-1300 0 1300-1400 1 1 1400-1500 1 2 3 1500-1600 1 1 1 3 1600-1700 123 13 10 1700-1800 1 1 2 1800-1900 1 2 3 1900-2000 2 2 4 2000-2100 1 1 1 3 2100-2200 0 2200-2300 0 2300-2400 0 2400-2500 1 1 222252 7 0 31 TABLE 117. SIZE OF BIRDS AT AGE OF 216 WEEKS, SUBJECT; SIZE OF EGGS FROM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .66 ± .070 45 47 49 51 53 55 57 59 61 63 1200-1300 1300-1400 1400-1500 1500-1600 1600-1700 1700-1800 1800-1900 1900-2000 2000-2100 2100-2200 2200-2300 1 1 1 1 1 3 1 111 4 1 1 1 3 1 1 1 2 5 1 1 2 4 1 1 3 2 1 3 1 1 2 1 1 1 1 222242 7 0 1 30 STUDY OF SELECTIONS FOR SIZE, .SHAPE, AND COLOR OF HENS' EGGS 303 TABLE 118. SIZE OF BIRDS AT AGE OF 2?0 WEEKS, SUBJECT; SIZE OF EGOS FROM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .69 ± .034 45 47 49 51 53 55 57 59 61 63 1200-1300 1300-1400 1400-1500 1500-1600 1600-1700 1700-1800 1800-1900 1900-2000 2000-2100 2100-2200 1 2 1 1 111 1 1 1 2 2 1 1 1 3 1 1 1 1 3 1 1 2222428701 1 3 4 3 5 5 3 5 0 1 30 TABLE 119. SIZE OF BIRDS AT AGE OF 224 WEEKS, SUBJECT; SIZE OF EGGS FROM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Coefficient of correlation = .40 ± .103 1100-1200 1200-1300 1300-1400 1400-1500 1500-1600 1600-1700 1700-1800 1800-1900 1900-2000 2000-2100 45 47 49 51 53 55 57 59 61 63 1 1 xl 1 2 1 1 1 1 1 1 1 1 2 1 2 1 1 1 1 1 1 1 1 1 1 1 222242 7 0 1 1 1 2 5 7 4 3 4 2 1 30 304 EARL W. BENJAMIN TABLE 120. SUMMARY OF TABLES 63 TO 119. SIZE OF BIRDS AT FOUR-WEEKS PERIODS DURING THEIR LIFE, SUBJECT; SIZE OF EGGS FROM WHICH RESPECTIVE CHICKS WERE HATCHED, RELATIVE Age of chicks Coefficient of correlation r Er Number of indi- viduals 1 day .73±.013 56.15 573 4 weeks 20± 037 5 41 299 8 weeks 14± 038 3 68 302 12 weeks 20± 040 5 00 262 16 weeks 19± 040 4 75 259 20 weeks .18±.040 4 50 261 24 weeks .15±.066 2 27 140 28 weeks .12±.039 3 08 287 32 weeks .31±.036 8 61 286 36 weeks * .33±.037 8.92 269 40 weeks 28± 038 7 37 269 44 weeks 34 ± 035 9 71 263 48 weeks 27 ± 039 6 92 258 52 weeks 25± 039 6 41 258 56 weeks. . . 28± 039 7 18 258 60 weeks .37±.037 10 00 254 64 weeks .40±.036 11 11 251 68 weeks .30+. 039 7 69 248 72 weeks 29 ± 040 7 25 244 76 weeks 23± 043 6 05 223 80 weeks .... 24db 048 5 00 178 84 weeks . . ... .33± 054 6 11 125 88 weeks .30± 057 5 26 115 92 weeks .30± 055 5 45 123 96 weeks 40± 051 7 84 122 100 weeks 35 -t 055 6 36 115 104 weeks 32db 057 5 61 113 108 weeks 34± 056 6 07 113 112 weeks 25 ± 060 4 17 112 116 weeks . 28± 059 4 75 112 120 weeks .29± 059 4 92 108 124 weeks .41=b.054 7 59 109 128 weeks 33 -t 069 4 78 75 132 weeks 42 ± 074 5 68 56 136 weeks 44± 077 5 71 51 140 weeks 41± 071 5 77 62 144 weeks 44± 074 5 95 54 148 weeks 49± 070 7 00 54 152 weeks 156 weeks .52±.068 .50± 078 7.65 6 41 52 42 160 weeks .48± 072 6 67 52 164 weeks 43 ± 078 5 51 50 168 weeks 50± 072 6 94 49 172 weeks 52± 070 7 43 50 176 weeks.. .44+. 082 5.37 44 STUDY OF SELECTIONS FOR SIZE, SHAPE, AND COLOR OF HENS' EGGS 305 TABLE 120 (concluded) Age of chicks Coefficient of correlation r Er Number of indi- viduals 180 weeks .37±.108 3 43 29 184 weeks 52=b 085 6 12 34 188 weeks 60± 099 6 06 19 192 weeks 196 weeks 200 weeks .59±.079 .48±.093 .56±.084 7.47 5.16 6.67 31 31 30 204 weeks 66± 068 9 71 31 208 weeks 49± 092 5 33 31 212 weeks 68± 065 10 46 31 216 weeks 66± 070 9 43 30 220 weeks 69± 064 10 78 30 224 weeks 40± . 103 3 88 30 DISCUSSION OF RESULTS The results of these studies are neither in entire accord nor in entire discord with any of the important studies of the same factors made by other workers. Up to the present time no extensive work has been reported on Single Comb White Leghorn material. So far as is known by the writer, no other study of these particular factors has been made with similar lines of inheritance over as long a period as is here reported. The studies have been made with vitally important commercial factors in a commercial breed. It is especially incumbent on the eastern pro- ducer to excel in the production of these desired factors in order to compete with more distant production. Therefore the fact indicated by these studies, namely, that the characters in question are distinctly inherited, should be gratifying and encouraging to commercial poultrymen who have been working for years along these lines. The inheritance of the characters studied seemed to be thru the medium of both the male and the female parent. The writer found no evidence of distinctly sex-linked factors, such as were observed by Pearl (1912) and by Hadley (1913). According to the writer's results, benefit to the flock can be gained for any of these inherited characters by adding either better males or better females to the flock. The relation of an individual egg to the mean type produced by the parent bird, and the relation of the type of egg incubated to the mean 306 EARL W. BENJAMIN type produced by the progeny, point directly to an easy way of improving a commercial flock by careful selection of the eggs for hatching. The results of this investigation show that a study of all the eggs produced by the parent hen, such as would be possible only by trap-nesting, would be more dependable than a selection of the incubated eggs alone; but the latter method is found to be a possible way, as well as an easier and quicker way, of obtaining good results. The fact that the size, the shape, or the color of eggs doe's not affect their incubation record, leaves the poultryman free to select his eggs for hatch- ing according to his own preference without its. affecting the percentage of hatch. The old opinion that hens' eggs approach a definite standard, to which they adhere more uniformly as the bird becomes older, is not borne out by the results of those studies. From this work it seems that the variability of a hen's production does not decrease as the hen becomes older. If the indication shown here is a fact, it does away with one of the several arguments which the poultryman has for using hens' eggs instead of pullets' eggs for hatching. The work of Pearl (1909) with Plymouth Rocks does not show agreemsnt with this theory. There S33m to b3 no gradual and consistent changes thruout the life of the bird for any of the threo egg characters studied. Nearly all of the changes noted occur between the productions of the first and the second year. Since the eggs produced during the second year are nearer to the mean for the entire life production of a bird kept for from thres to four years, it would b3 expected, and was found generally, that the eggs selected for incubation produced by hens two years old or older, gave more consistent correlations than those produced by pullets. The positive relation of the size of the egg incubated to the size of the resultant chick and mature bird, is of value to poultrymen who are inter- ested in the production of either poultry or eggs. The inheritance of the characters studied is undoubtedly of the type of a Galton regression. Much further study is needed in order to properly analyze the unit factors, or physiological units, involved in the formation of the broad practical characters here observed. Until further results are available, however, the fact that certain general lines of inheritance ars known gives breeders some evidence on which to base more work for the improvement of their flocks. STUDY OF SELECTIONS FOR SIZE, SHAPE, AND COLOR OF HENS' EGGS 307 SUMMARY The most important results obtained from the studies reported in this paper may be grouped into the following conclusions: 1. The variability of a bird's production for a certain character does not depend on the difference existing between that bird's parents for the same character. 2. Both the male and the female have a distinct and approximately equal effect on the type of egg produced by the progeny, but the combined effect of the two is much greater and is directly inherited by the progeny, as is shown by the type of egg produced. 3. A mating of two opposite extremes of character always caused the production of a medium character in the progeny. 4. A mating of two similar extremes of character usually caused the production of a character approaching normal, in the progeny. 5. It appears that small size and length of egg are dominant, while there seems to be no dominancy whatever for color. 6. The correlations between the type of egg incubated and the mean type produced during the life of the respective progeny, are positive in every instance and are significant except for the color character. These correlations are not so significant as those between the mean types of eggs produced by the parents and the respective progeny. 7. The color character is much more irregular than the size or the shape, and less reliance can be placed on the stability of any color type when selecting eggs for hatching. 8. It does not appear that any more reliance can be placed on the stability of the progeny type hatched from hens' eggs than on that hatched from pullets' eggs. 9. The type of egg incubated affects the mean type of egg produced during the life of the bird hatched, to a greater extent than it affects the pullet-year production or the production of any other single year. 10. A strong correlation exists between the types of eggs produced by individuals and the types of eggs from which these individuals were hatched. 11. There is no correlation between the size and the shape of eggs produced by the birds used in this experiment. 12. The size, the shape, and the color of the egg seem to have no effect on its incubation record. 308 EARL W. BENJAMIN 13. No definite tendency is shown toward a reduction of the variability of type of eggs produced by individual birds during successive years. 14. During the pullet year the size of the eggs produced increases rapidly, but after the first year's production no appreciable change in the size of the eggs produced can be found. 15. There seems to be no perceptible and consistent difference between the shapes of eggs laid by pullets and those laid by hens. 16. There is a tendency for the eggs produced each year, even in the pullet year, to have a gradually increasing index until the fifth or the sixth month of production, after which this index gradually decreases until the season's production ceases. 17. The eggs produced by hens two years old or older, are more likely to be tinted, or are tinted darker, than the eggs produced by the same birds during their pullet year. 18. There is no gradual darkening of the shell pigment after the second year's production. 19. Each year there is a tendency for the eggs produced to gradually become whiter during the first five or six months of production, and then to become more tinted again toward the end of the production season. 20. The data presented show that when eggs are laid by an individual bird for two or more successive days, the eggs become successively smaller, have a larger index, and are more deeply tinted. 21. A distinct positive correlation is found between the size of the eggs incubated and the vigor of the respective chicks hatched, at various ages of the chicks. The correlation is especially significant during the period of severe weather conditions. 22. A constant figure to represent x in the ratio, female weight : male weight : : x : 1, was calculated for a part of the available material at various ages, and this figure was found to agree closely with Galton's constant for human stature of 0.93. 23. There is a significant positive correlation between the size of the eggs incubated and the size of the respective chicks hatched. This correlation persists during the life of the birds as far as it was studied; that is, during a period of 228 weeks. 24. All of the eggs produced by any one hen tend to be of a characteristic type as to size, shape, and color. STUDY OF SELECTIONS FOR SIZE, SHAPE, AND COLOR OF HENS' EGGS 309 25. Certain individuals have the power to transmit their characters much better than do others. 26. The results of these studies indicate a condition of inheritance resembling a Galton regression, for all characters studied. ACKNOWLEDGMENTS The materials and equipment used for this study were supplied by the Department of Poultry Husbandry of the New York State College of Agriculture at Cornell University. The writer wishes to express his appreciation for these facilities and for the valuable advice furnished by Professor James E. Rice, of the Department. The helpful suggestions given by Dr. H. H. Love, of the Department of Plant Breeding at Cornell University, are also appreciated. 310 EARL W. BENJAMIN BIBLIOGRAPHY ATWOOD, HORACE. Some factors affecting the weight, composition, and hatchability of hen eggs. 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