FERTILITY AND HATCHING OF EGGS. I5I 



observed in "pure lines" in plants ( Johannsen ) in the case of a 

 sexually reproducing (i. e., not self- fertilizing) organism. 



3. Fertility and hatching quality again are seen to behave 

 differently. There is no evidence of any kind that the former 

 represents an innate, constitutional character which is inherit- 

 able. 



SUMMARY OF SECTION. 



Putting all the results of this section together it may be said 

 that the data at present available indicate that the hatching 

 quality of eggs measured by per cent, of fertile eggs hatched is 

 an innate constitutional character which is definitely inherited 

 in the female and probably also in the male line, though on the 

 latter point more data are needed. On the other hand, there 

 is no evidence that the character "fertility of eggs" is in any 

 degree or manner inherited. 



Summary and Discussion of Results. 

 The data represented in this paper lead to results which may 

 be summarily stated as follows : 



1. So far as the present data indicate there is a small but 

 still sensible correlation between the fertility and hatching 

 quality of eggs. This means that in general or on the average 

 the hen whose eggs run high in fertility will also tend to show 

 a high hatching quality of eggs (per cent, of fertile eggs 

 hatched) and vice versa. 



2. Conditions of housing have a marked and definite influ- 

 ence on the mean or average fertility and hatching quality of 

 eggs. In the experiments here discussed it was found that both 

 fertility and hatching quality of eggs were very much better 

 when the breeding was done in a "curtain-front" house, which 

 furnished an abundance of fresh, pure air, than when it was 

 done in what was formerly considered to be a highly desirable 

 type of heated house, without curtain-front but with a sup- 

 posedly adequate system of indirect ventilation. 



3. The hatching quality of eggs is in general less variable 

 in proportion to the mean of the character varying than is 

 fertility. 



4. The variability in respect to both fertility and to hatching 

 quality is markedly influenced by environmental conditions 

 (particularly housing conditions). 



