58 THE PHYSIOLOGY OF REPRODUCTION 



in the lioness oestrus has been known to recur at intervals of 

 three weeks until the animal became pregnant, while the period 

 of oestrus may itself last a week. 1 Further, the lioness may 

 experience three or four sexual seasons in the year, as in the 

 domestic cat, this having been observed to occur in the lioness 

 in the Dublin Zoological Gardens when copulation had not 

 been successful, or when the animals were not permitted to 

 breed. If allowed to become pregnant the lioness at Dublin 

 may still experience two sexual seasons, and have two litters of 

 cubs within the year. The puma in the Dublin Gardens is 

 stated to have one sexual season annually if breeding, or two 

 if there is no gestation. The larger Felidae as a rule breed com- 

 paratively freely in confinement, some places, such as the 

 Dublin Gardens, being famous for successful lion breeding. The 

 period of gestation in the lioness is from fifteen to sixteen weeks ; 

 that of the tigress is about twenty-two weeks ; while the puma 

 goes with young for fifteen weeks. 



Most species of bears, both in their wild state and in confine- 

 ment, are moncestrous and have one annual sexual season. The 

 grizzly bear, however, according to Somerset, 2 bears young only 

 once in two years. The bears in the Zoological Gardens at 

 Dublin, on the other hand, may experience more than one 

 annual sexual season if pregnancy does not occur. The period 

 of gestation in the brown bear is seven months ; in the grizzly 

 bear it is probably longer. Heape states that with the bears in 

 the Zoological Gardens in London oestrus may be experienced 

 for two or three months continuously ; but this condition, as he 

 points out, is unnatural and probably an effect of confinement, 

 for though coition can occur, it does not, as a rule, result in 

 pregnancy. 



The ferret, which is a domesticated variety of the polecat, 

 is monoestrous, but may have as many as three annual sexual 

 seasons, 3 which, however, instead of being distributed at regular 

 intervals throughout the year, occur only in the spring and 

 summer, the autumn and winter being occupied usually by a 

 prolonged ancestrous period. This tendency towards a con- 



1 See Marshall and Jolly, loc. cit. 



- Somerset. Quoted by Heape, loc. cit. 



3 Carnegie, Ferrets and Ferreting, London. 



