THE REPRODUCTIVE ORGANS 



405 



Excluding lactating and immature whales the number of Fin whales of which the 

 mammary glands have been sectioned is thirty-three and of Blue whales eight. The 

 numbers of these occurring in each condition are as follows : 



Taking pregnant whales first it is found that only in one case was there a mammary 

 gland in the intermediate condition. This whale, No. 175, had a foetus measuring 

 over 6-0 m. which was evidently about to be born, and there is no doubt that the lobules 

 of the glands were beginning to develop in preparation for active secretion. Now, 

 where the gland is found in this condition in whales which are not pregnant it must 

 be supposed that, lactation having ceased, the gland is now reverting to the normal 

 resting condition, and since the ratio of the intermediate to the resting conditions is 

 7 to 3 among Fin whales and 3 to i among Blue whales it can only be supposed that 

 though the development of the gland is rapid at the end of pregnancy, its involution 

 after the period of secretion is very slow. It seems improbable that the majority of 

 "intermediate" non-pregnant whales had only just finished lactation, since the resting 

 whales are caught in far greater numbers than the lactating whales — a fact which 

 argues that the resting period is correspondingly longer than the lactating period or 

 at least as long, even if the nursing mothers lead a more secluded life less open to the 

 attacks of whale boats. 



Since the intermediate stage is never found in pregnant whales except at the approach 

 of parturition it follows that the involution of the gland is always completed before 

 pregnancy again takes place, but since in some young but clearly adult whales the 

 gland is sometimes found in a state far less developed than the normal resting condition, 

 it is to be supposed that it becomes permanently altered after the first pregnancy. 



THE TESTES 



It is well known that in Cetacea the testes remain permanently in the abdominal 

 cavity. In the whalebone whales, as explained on p. 267, they can be found without 

 difficulty near the abdominal wall at the posterior end of the cavity. The testis is a 

 rounded cylindrical organ, the size of which is subject to considerable variations which 

 are very difficult to correlate with any particular factor. However, it is worth while 



