THE REPRODUCTIVE ORGANS 401 



cells together with blood corpuscles were, however, present. If this second case is 

 typical it suggests that extravasation of blood may not continue throughout pregnancy. 



The smear from the ovulating whale differed entirely from those from the pregnant 

 whales. There were many isolated epithelial cells present, with many other cells with 

 smaller nuclei of doubtful origin. As one would expect from observations on sections 

 of the uterine mucosa, no blood corpuscles could be seen. 



In lactating whales the epithelial cells and red blood corpuscles were few. In No. 271 , 

 which had a uterus of 17-0 cm., more epithelial cells were present than in No. 244. 

 In these whales apparently the extravasation of blood had almost ceased. 



THE MAMMARY GLANDS 

 The mammary slits are situated on either side of the genital groove, and lie parallel 

 to it. The teats are normally completely withdrawn and invisible, but in lactating whales 

 drawn on to the flensing platform they are more or less everted, though not always 



Fig. 134. Diagram of ventral view of whale to show position of mammary glands, m.g., outline of mam- 

 mary glands; r.a., reproductive aperture; t., teat in mammary groove; a., anus; «., umbilicus; v.g., 

 endings of ventral grooves. 



completely. Sometimes when plenty of milk is present the pressure of the carcass on 

 the edge of the platform causes it to spout from the teat in such a way that a sample 

 can be collected sufficiently pure for chemical analysis. An account of the composition 

 of whale's milk appears in Appendix I. 



A good description of the mammary glands of the Humpback is given by Lillie 

 (1915, p. loi). This however deals mainly with the gross anatomy of the gland and the 

 process of suckling, while we are concerned more with the changes which take place 

 in the gland in the different phases of the sexual cycle. 



In Blue and Fin whales the mammary glands lie between the blubber and flesh and 

 are situated almost entirely anterior to the teats. They are of an elongated pear-shape, 

 the apex of the pear being anterior to and remote from the teats (Fig. 134). The length 

 of the gland is about 2 m. and its depth varies according as to whether the whale is 

 sexually mature or immature and whether milk is being secreted or not. In an immature 

 whale the gland is usually not more than 2 cm. deep at the widest part. In a mature 

 whale it is usually 5 to 6 cm. deep, and in a lactating whale 15 to 30 cm. deep. When 



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