COLD-BLOODED VERTEBRATES 



1039 



orction of male hormone (Altland, 1951). 

 In the musk turtle, Sternotherus, on the 

 other hand, interstitial cells are present but 

 show no seasonal variation (Risley, 1938). 



Franz von Leydig (1821-1908), the Ger- 

 man anatomist and zoologist whose name 

 enters into the eponym for the interstitial 

 cells, observed them (1857) in the testis of 

 a lizard, Lacerta agilis. Since then, the cells 

 have been seen in the testes of several lac- 

 ertilians.^ Herlant (1933) and Regamey 

 (1935) state unequivocally that in the liz- 

 ards they studied the development of the 

 interstitial gland and of the secondary sex 

 characters is correlated. Interstitial cells 

 have also been noted in the testes of several 

 snakes.^ Herlant (1933) reported no sea- 

 sonal variation in number, size, etc., of the 

 interstitial cells in Vipera and Tropido- 

 yjof.us, but Vols0e (1944) observed maximal 

 development of the cells in Vipera in the 

 early spring, shortly before the mating sea- 

 son. Fox (1952), reviewing the situation 

 for reptiles generally, concluded that "the 

 maximal interstitial cell size occurs during 

 the breeding period although in certain spe- 

 cies the cells may be relatively large during 

 other seasons as well." Since secondary sex 

 characters become conspicuous during the 

 breeding season and the interstitial cells 

 give indication of activity at this period or 

 a little earlier, the presumption is strong 

 that the two phenomena are related. 



Interstitial cells are absent from the testis 

 of the innnature alligator (Forbes, 1940a). 

 There seems to be no information on 

 whether interstitial tissue occurs in adult 

 Grocodilia. 



""AjioHs (Fox, 1958), Phrynosorna (Blount, 

 1929), Uromasiix (Kehl, 1935, 1944b), Hemidacty- 

 bis (Dutta, 1944), Xantusia (Miller, 1948), Scincus 

 (Kehl, 1935, 1944b), Acanthodactylm (Kehl, 1935, 

 1944b), Takydromus (Takewaki and Fukuda, 

 1935a), Lacerta (Frankenberger, 1922; Reiss, 1923a, 

 b; Pellegrini, 1925; Herlant, 1933; Stieve, 1933; 

 van den Broek, 1933; Regamev, 1935), Aiiguis 

 (Ganfini, 1902; Dakq, 1920; Herlant. 1933). Helo- 

 derma (Pesce, 1935), and Varanus (Hoberer, 1930; 

 Kehl, 1935, 1944b). 



"Boa (Ganfini, 1902), Matrix (Tropidonotus) 

 (Herlant, 1933), Coluber (Zamenis) (Ganfini, 

 1902; Pesce, 1935), Thamnophu (Eiitcnin) (Cies- 

 lak, 1945; Fox, 1952), and Vipcm (Herlant, 1933; 

 Vols0e. 1944). 



IV. Excurrent Pathways for Sperm 



Fish 



In cyclostomes the testicular cysts rup- 

 ture and release mature sperm into the coe- 

 lom, from whence they escape to the ex- 

 terior by way of a genital papilla (Conel, 

 1917; Hoar, 1957a). In higher forms sperm 

 are carried in "vasa deferentia," but these, 

 according to Eggert (1931), are not homol- 

 ogous with the structures of the same name 

 in amniotes. ''Vasa deferentia" and testes 

 may be paired or single (Geiser, 1922; 

 Oslund, 1928; Matthews, 1938; Chavin and 

 Gordon, 1951). 



Courrier (1922b) observed seminal vesi- 

 cles in the stickleback, as did Eggert (1931) 

 in Periophthalmus, but the latter believes 

 that the seminal vesicles are not homolo- 

 gous with those of mammals. In Gillichthys 

 the vesicles are large structures caudal to 

 the testes proper. Their function is uncer- 

 tain, but may simply be to store sperm. 

 They do not change their appearance sea- 

 sonally, are not affected by the administra- 

 tion of testosterone, and presumably are 

 not under endocrine control (Weisel, 1949). 

 The sperm ducts are secretory in the tele- 

 ost, Astyanax (Rasquin and Hafter, 1951). 

 The goby and the blenny have glandes an- 

 nexes at the caudal ends of the testes; when 

 the interstitial tissue of the testis is in- 

 creased in volume, the tubes of the glandes 

 annexes are dilated with colloid secretion. 

 These are glands of external secretion ; their 

 product has been compared to that of the 

 prostate, but the function of the secretion 

 is uncertain (Vivien. 1938; Coujard, 1941a, 

 b). 



Amphibians 



The duct systems whereby sjierm are col- 

 lected and conveyed to the exterior have 

 been comprehensively described by Noble 

 (1931) in his admirable book on the am- 

 phibians. Several fine tubules, the vasa ef- 

 ferentia, join the testis directly or indirectly 

 to the mesonephros, which in amphibians is 

 also the functional kidney. In most genera 

 the vasa efferentia empty into glomerular 

 capsules. The sperm then traverse the uri- 

 nary collecting tubules and the meso- 

 nephric (Wolffian) duct to reach the cloaca. 



