MALE GENITAL SYSTEM: INTERNAL ORGANS 



38 S 



transverse fibrous cord which runs immediately in front of the base of the penis. 

 (In Fig. 1 this is shown severed to allow the walls of the abdomen to be pulled apart.) 



In the foetus 1-23 m. in length both testes measured 2-9 x o-8 x 07 cm. 



In the foetus 2-65 m. in length the testes measured: right 7-5 x 1-2 x 1-4 cm.; left 

 7-5 x 1-2 x i-i cm. 



In older whales the discrepancies between the measurements of the testes of the two 

 sides become greater. The following is a selection from the measurements and weights 

 of the testes of Fin whales measured at the whaling station during the season 1 930-1. 

 The lengths, breadths and depths are shown for testes of whales of various lengths. 



It is seen from the above that there is great variation in the size of the testis in whales 

 of the same length, and that in any individual the right testis is longer than the left but 

 not so wide. From the routine measurements of a great number of testes it is clear that 

 the organ increases in size fairly evenly with the growth of the body up to sexual 

 maturity, when the testis enlarges very greatly. After sexual maturity has been reached 

 there is no correlation between the body length and the size of the testis. This is 

 illustrated in the above table, since the testis of a whale 217m. in length is smaller than 

 that of the 20-6 m. individual and almost the same size as that of the 20-2 m. whale. 



The growth and histology of the testis has been dealt with in detail by Mackintosh 

 and Wheeler (1929, pp. 407-12) and the minute anatomy of the organ of Neomeris 

 phocaenoides by Chi Ping (1926). In the Fin whale, as in Neomeris, the lobules of the 

 testis substance occupy the whole space enclosed by the tunica albuginea and there is 

 no mediastinum testis. In the antero-dorsal region of the testis there is a thickening of 

 the septal membranes through which the vasa efferentia pass to the caput epididymis. 

 The vasa efferentia are few in number, and after numerous sinuosities in the caput, join 

 together to form a single much convoluted duct forming the cauda epididymis. 



The whole testis and epididymis are enclosed together in the reduplication of the 

 peritoneum forming the suspensory ligament of the testis and the ligamentum latum. 

 Anthony detected radiating muscle fibres in the mesentery which he supposed were the 

 vestiges of a cremaster muscle, but no trace of these was found in the Fin whale. There 

 is no vaginal cavity surrounding the testis, since, as in Neomeris, the tunica vaginalis and 

 the tunica albuginea are adherent to one another. In Mesoplodon there is a vaginal cavity 



