BREEDING FOR EGG PRODUCTION. 53 



producing capacity of eggs, and diat die assumption of unifomi 

 fertility in the eggs of each hen for considerable periods of time 

 was not sustained. 



In the table on pages 54 and 55 there is given, in addition to 

 the tgg yield of 76 hens, an incubation test of the eggs laid 

 during the last 10 days of May, 1902. 



The data show plainly the great variability in the fertility of 

 the total tgg yield of different hens ; some birds yielding eggs 

 that are all highly fertile, and others giving eggs that are all 

 completely infertile, being as clear after 21 days of incubation 

 as at the start. Again some hens are very irregular in the 

 fertility of their eggs ; an tgg laid one day yielding a chick, 

 while that laid on the next is completely infertile ; or they are 

 fertile for a day or two, or more, and then infertile, becoming 

 fertile again after one, two, or more eggs are laid. This seems 

 to be true with some individuals, whether they are laying reg- 

 ularly or irregularly, or whether they have been laying a long 

 or a short time. The eggs from other hens seem to be slightly 

 fertile, the embryo dying before the tenth or twelfth days. This 

 appears to be regular with some hens, and irregular with others ; 

 as some give eggs of low fertility one day and high fertility on 

 the days immediately following, or preceding. 



The results given in the table plainly show the great variability 

 in fertility. For instance ; the tgg of the first hen on the list. 

 No. 511, was laid ]\Iay 21st, and it stopped developing about the 

 centh day of incubation. The next one was laid May 24th and 

 it yielded a good chick. Both eggs were in the same incubator, 

 on the same shelf, where there is every reason for believing that 

 the conditions were alike. The next egg was laid by the same 

 hen two davs later — Mav 26th — and the g^erm died on the six- 

 teenth day of incubation. She laid an egg the next day follow- 

 ing and development stopped in it on the tenth day of incubation. 

 The next eggs were laid by her on the 29th and 30th insts, and 

 both vielded good chicks. 



During this ten days test she laid six eggs, three of which 

 yielded chicks, and in three of which development stopped after 

 having advanced half the period, or more. Had these six eggs 

 been taken promiscuously and divided into two lots wdiich were 

 treated differently, three chicks possibly might have been secured 

 from one lot, and three, half developed dead chicks, from the 



