366 THE POPULAR SCIENCE MONTHLY 



duct, is not enough to insure that a hen shall lay eggs, that is, exhibit 

 actual as well as potential fecundity. While comparatively very rare, 

 cases do occur in which a bird possesses a perfect ovary and perfect 

 oviduct and is in all other respects entirely normal and healthy, yet 

 never lays even a single egg in her life time. Such cases as these prove : 

 first, that what we may call the anatomical factor is not alone sufficient 

 to make potential fecundity actual ; and second, that the anatomical and 

 physiological factors are distinct, in the sense that the normal existence 

 of one in an individual does not necessarily imply the coexistence of the 

 other in the same individual. 



Turning now to the physiological factors involved in fecundity, it 

 would appear that there are at least two such factors or groups of 

 factors. The first of the physiological factors involved may be desig- 

 nated the "normal ovulation" factor. By this is meant the complex 

 of physiological conditions which, taken together, determine the laying 

 of about such a number of eggs as represents the normal reproductive 

 activity of the wild Gallus bankiva. It must be remembered that, for 

 reasons which can not be gone into here, under conditions of domestica- 

 tion the activity of this normal ovulation factor will mean the produc- 

 tion of considerably more eggs than under wild conditions. Egg pro- 

 duction involves certain definite and rather severe metabolic demands, 

 which under wild conditions will not always, or even often be met. 

 Further, as has been especially emphasized by Herrick, egg-laying in 

 wild birds is simply one phase of a cyclical process. If the cycle is not 

 disturbed in any way the egg production is simply the minimum 

 required for the perpetuation of the race. If, however, the cycle is 

 disturbed, as, for example, by the eggs being removed from the nest as 

 fast as they are laid, a very considerable increase in the total number of 

 eggs produced will result. 



It is a fact well known to poultrymen, and one capable of easy 

 observation and confirmation, that different breeds and strains of 

 poultry differ widely in their laying capacity. In saying this the 

 writer would not be understood to affirm that a definite degree of 

 fecundity is a fixed and unalterable characteristic by any particular 

 breed. The history of breeds shows very clearly that certain breeds 

 now notably poor in laying qualities were once particularly good. One 

 of the best examples of this is the Polish fowl. But, in spite of this, 

 not only do these breed and strain differences in fecundity exist, and 

 probably always have existed, but they are inherited. Such inherited 

 differences are independent of feeding or any other environmental 

 factors. Thus a strain of Cornish Indian Games with which I have 

 worked are poor layers, regardless of how they are fed and handled. 

 This is merely a statement of particular fact; it does not imply that 

 there may not exist other strains of Cornish Indian Games that are 

 good layers. 



