FERTILITY AND HATCHIN'G OF EGGS. 



127 



14.14% from Table VI. This indicates again how direct and 

 important an influence housing conditions have upon the fer- 

 tihty of the eggs of breeding birds. 



4. It is of some interest to compare the fertihty records of 

 the same male bird in his first and second breeding years, 

 though the amount of data available for such comparison in 

 the present statistics is small. The four birds D 56, D 11, 

 D 58, and D 31 appear in both Table VII and Table VIII. 

 Their records of average pen fertility of eggs in the two years 

 are as follows : 



Average Percentage of Infertile Bggs. 



Mile bird. 



1908. 

 (Cackerel year.) 



1909. 

 (Cock year.) 





D 56 



27.0% 



29.8% 





D 11 



22 . 4% 



12.0% 





D 58 



9.7% 



3.9% 





D .31 



8.9% 



6.3% 





Of these four birds only one (D 31) did his breeding under 

 identical housing conditions in the two years. In this case 

 there is practically no difference in the average fertility. In 

 two cases (D 11 and D 58) there is a very considerable reduc- 

 tion in the average percentage fertility, but this is probably to 

 be explained almost entirely as the result of the action of the 

 better housing conditions of 1909 on the breeding birds, par- 

 ticularly the females. D 56 has a worse record for 1909 than 

 for 1908. but this bad average is due very largely to the effect 

 of three hens, viz: 1071, 1078, and 1083. with 100, 87, and 85 

 per cent of infertile eggs respectively. This is a heavy handi- 

 cap in an average based on only 15 birds. 



5. An examination of these tables and of the detailed hatch- 

 ing records. on which they are based emphasizes the value of 

 trap nesting breeding hens during the breeding season at least, 

 particularly if one is to engage in selling eggs for hatching. A 

 study of the records shows that it would have been possible 

 to have thrown out early in the hatching season such poor 

 performers as. for cxam])le Nos. t8. 415. 438, 784 in 1908. 

 and 1071, 1078, T083, iTio and 403 in 1909. These birds were 



