FERTILITY AND HATCHING OF EGGS. IO7 



regarding the points here raised is an almost absolutely neces- 

 sary prerequisite to any adequate interpretation of the results 

 of experiments on incubation. 



The questions here raised are fundamental ones, intimately 

 related to the general physiology of reproduction in the domes- 

 tic fowk The significance of a solution reaches farther than 

 simply answering the immediate questions raised. For if it 

 can be shown that these characters, fertility and hatching qual- 

 ity of eggs, are innate and unique qualities of the individual 

 and are definitely inherited we shall then have a sure basis on 

 which to proceed towards improving them by breeding. That 

 there is room for improvement here is not to be doubted. The 

 number of eggs which it takes to make a healthy chicken is a 

 very important factor in the poultry industry, and one on which 

 more than one otherwise promising commercial venture has 

 been wrecked. Further, certain of the questions to be here 

 discussed have a direct bearing on important problems of 

 organic evolution in general. Thus the question of whether 

 the fertility and hatching capabilities of eggs are correlated 

 with fecundity (here measured by winter egg production) is 

 one on which data are almost entirely wanting for any organ- 

 ism. Yet this is a question of prime importance in any dis- 

 cussion regarding the struggle for existence following the 

 migration of a form into a new habitat. Definite data obtained 

 under controlled experimental conditions regarding this corre- 

 lation are needed. 



Material and Methods. 



At the beginning of the hatching season of 1908 a system of 

 extensive and detailed records regarding the fertility and hatch- 

 ing of eggs was inaugurated in connection with the poultry 

 work of the Station. For all eggs which have been incubated 

 since that time the following facts are known: i. The hen 

 that laid the egg. 2. The male bird that was in the pen with 

 this female and which fertilized the egg, if it was fertilized. 

 3. The number of the pen and the number of the house in wdiich 

 these birds were kept. 4. The incubator in which the egg was 

 placed. 5. The date at which the egg was laid. 6. The date 

 at which it was put into the incubator. 7. The date or dates 

 at which it was tested. 8. Whether the egg was (a) infertile, 

 or (b) started to develop but the embryo died early in incuba- 



