128 MAINE AGRICULTURAL EXPERIMENT STATION. I9I4. 



The egg then represents not a normal organic part of the 

 individual but a discrete unit of production of certain corre- 

 lated organs. The size and form of such units are to a cer- 

 tain extent dependent upon the size and form of these organs. 

 But the size, form and frequency are necessarily also dependent 

 upon the physiological tone of the organs and of the entire 

 organism. 



It is not strange that the same individual at different 

 seasons and different individuals throughout the year may 

 show variations in egg size and in the number of eggs produced 

 which are out of proportion to the variation in body size. It 

 is quite possible that egg production like milk production * is 

 related to the amount of food consumed above maintenance. 

 That is the bird which lays large eggs and many of them is 

 one which in addition to the organic potentiality to lay eggs 

 of this size possesses also both the physiological capabilities of 

 digesting a large amount of food above the amount required 

 for the maintenance of the body and of using this absorbed 

 food for the production of yolk, albumen, etc. The fact that 

 the same individual lays larger eggs and more of them at cer- 

 tain seasons than at others may be due to the fact that she is 

 capable of digesting and utilizing for egg production more 

 food at those seasons. It has in fact been shown by Rice ** 

 that the number of eggs produced by a flock is positively cor- 

 related with the amount of food consumed, and the fluctuations 

 which he found characteristic for the amount of food consumed 

 are very similar to the seasonal fluctuation in egg weight. The 

 work of Riddle t on yolk formation also supports this view. 



In general the conditions which favor the production of a 

 large number of eggs also favor the production of large eggs 

 (i. e., large for the particular individual). Yet there are 



*Eckles, C. H., and Reed, O. E. A Study of the Cause of Wide 

 Variation in Milk Production in Dairy Cows. 'Mo. Agr. Expt. Sta. Re- 

 search Bui. No. 2, 1910, pp. 107-147. 



** Rice, J. E. The Moulting of Fowls. Cornell Univ. Exp. Sta. Bui. 

 258, 1908, pp. 21-68. 



t Riddle, Oscar. On the Formation Significance and IChemistry of 

 White and Yellow Yolk of Ova. Journal of Morphology, Vol. 22, 191 1, 

 pp. 456-484- 



