350 



WHALES 



Figure igs. Diagrammatic left view of the sexual organs of a male porpoise. AI = muscles of 

 the back; D = diaphragm; A = adrenal gland; K -=- kidney; T = testicle; E = epi- 

 didymis; V = vas deferens; B = pelvic bone; Rp — retractor penis muscle; P = penis; 

 Ps = genital slit ; U = umbilicus; An — anus. 



feet six inches long and weigh up to loo pounds. (The testes of Fin Whales, 

 Sei Whales and Sperm Whales weigh sixty, fifteen and twenty-five pounds 

 respectively.) We have seen that their position inside the body is an 

 advantage in streamlining, but whether streamlining demands that they 

 be placed precisely where they are is a debatable point, the more so since 

 the testes of male sea-cows, of some insectivores, of elephants, sloths and 

 armadillos are in the same position. 



The fine structure of the testes is, by and large, no different from that 

 of the testes of all mammals, and so is that of the spermatozoa which, in 

 even the largest whales, are no larger than man's. From detailed micro- 

 scopic investigations it appears that while small qviantities of semen may 

 well be produced by whales throughout the year, a marked increase occurs 

 during the mating season. 



The spermatozoa are conveyed from the testes by a highly convoluted 

 duct, first to the epididymis which, in whales as in many other animals, 

 is an elongated organ close to the testes. From the epididymis they are 

 conveyed farther by the vas deferens, a tube which is convoluted either 

 over its initial section or else over its entire length, but is devoid of all 

 evaginations in which such accessory genital glands as the vesicular and 

 bulbo-urethral glands are normally found. (The only accessory genital 

 gland in Cetaceans is the prostate gland.) The vas deferens combines 

 with the ureter, and then, just as in other mammals, enters the penis from 

 below, and terminates at its tip. 



