SIZE, SHAPE AND PHYSICAL CONSTITUTION OF THE EGG. I27 



litter. It has also shown that the variation in successive eggs 

 ts as great at the end of the second as at the beginning of the 

 first year's laying. 



Discussion of Results. 



Only a beginning of the analysis of the factors which produce 

 variation in the eggs of the domestic fowl is possible from 

 the results of this investigation. 



Since the individual variation in egg characters is less than 

 race variation, and since the association of various pairs of 

 egg characters is greater within the egg of an individual thm 

 within the eggs of the race, it is concluded that an individual 

 inherits or, at least, possesses at sexual maturity, the tendency 

 to lay eggs of a certain particular and individual shape, i^^e 

 and physical constitution. 



The seasonal and cyclic fluctuations in the eggs of the indi- 

 vidual on the other hand show that this predisposition toward 

 eggs of a particular type and size may be influenced by physio- 

 logical and possibly also environmental conditions. 



That the individuality in egg characters is related to indivi I- 

 uality in other characters seems certain. The fact that "he 

 large varieties of hens lay larger eggs than bantams indicates 

 that within broad limits the size of the egg is related to body 

 size. The insignificance of the correlation coefficient between 

 egg size and body size for the egg of the individuals studied 

 however shows that this relation does not necessarily obtain 

 within narrow limits. It is not possible to decide the limits of 

 the relation of body size to egg size from so small a number 

 of individuals. The point is open to further investigation. 



In the study of egg characters it must be kept in mind that 

 eggs are quite different material than is usually employed in 

 biological studies of variation. They are not organs or parts 

 of organs that owe their size and shape to growth, i. e., the 

 proliferation of the cells of which they are made up. Each 

 egg is one modified cell and represents the accumulated results 

 of the activity of a great many cells, not a part of it. The 

 different parts of the egg arise from different organs or parts 

 of organs (the ovary and the parts of the oviduct) and by 

 quite distinct physiological processes (yolk deposition and 

 albumen, membrane, and shell secretion.) 



