THE "sexual season" OF MAMMALS. 15 



quality of that food, have very marked effects not only upon 

 breeding seasons and gestation periods, but upon fertility 

 generally, upon the mother and upon the foetus (Latarte, 1 891). 

 It is with such questions as these that the consideration of 

 the breeding season as a whole is concerned; with them the 

 following paper does not deal, and it is obvious that before 

 they can be profitably discussed, not only the sexual season, 

 but the gestation period must be examined separately. 



The Sexual Season of Female Mammals. 



In dealing with this subject we have to discriminate be- 

 tween mammals under three different conditions : namely, 

 wild animals in a state of nature, wild animals in captivity, 

 and domesticated animals ; and this is necessary, because the 

 generative system of wild animals is affected by the condi- 

 tions attending captivity, because the effect of captivity is 

 not necessarily the same as the effect of domestication, and 

 because wild animals cannot be examined so closely as the 

 others and less is known about them. 



In dealing with wild animals in captivity it is necessary to 

 bear in mind the fact that good food, warmth, and shelter 

 have a very great effect on the increase of the generative 

 powers of some animals, while on others a strange climate, 

 confinement, want of violent exercise, and probably the 

 absence of opportunity for periodic gorging of freshly killed 

 food, or of a sufficient variety of food, have the opposite 

 effect. 



As an example of the former the deer and cattle in the 

 Zoological Gardens may be quoted, as an example of the 

 latter some of the larger carnivora will stand. 



In dealing with domesticated animals we do not know 

 what the original conditions were, and we have to take the 

 facts as they stand. At the same time we may assume that 

 animals which do not show themselves to be prolific under 

 domestication are rarely domesticated, and that a very long 



