IX 



THE URINO-GENITAL SYSTEM 



General and Historical. 



This is perhaps the most widely and most accurately known system 

 in the entire animal. The majority of the older authors made 

 more or less accurate observations so far as the gross anatomy of the 

 kidneys, gonads and their ducts is concerned (see Historical Intro- 

 duction). Apart from such accounts the earliest author to study the 

 system in any detail was Leydig (1853), who added many histological 

 observations to his account. He observed and figured the recepta- 

 culum seminis^ but failed to realize its function. He also recognized 

 and correctly described the adrenal bodies, and he further figures 

 and describes a curious pear-shaped epithelial bladder attached to 

 the vestigial Miiller's duct in a male specimen, which he thought 

 was a vestige of an anterior part of the kidney (he of course did not 

 realize the true significance of Miiller's duct but thought it was 

 connected with the ureters). Spengel (1876), the next worker of 

 note, was unable to find anything which would correspond with the 

 structure described by Leydig. Spengel's account of the urino- 

 genital system of Amphibia is very detailed and accurate, and em- 

 braces all three classes (Gymnophiona, Urodela, and Anura) involv- 

 ing a number of genera in each class, and includes Salamandra. It 

 is mainly owing to his labours that the anatomy of this system is so 

 well known, and he deals not only with the macroscopic structures 

 but also with histological details of the kidney tubules, &c. There 

 has been no subsequent paper worthy of note dealing with the entire 

 system, although a number of authors have treated particular sections 

 in more detail. Their papers will be referred to later in the appropriate 

 places. A possible exception may be made with regard to Fiir- 

 bringer's paper (1878), which deals with the development of the 

 organs concerned, while Gray's (1932) work on the development of 

 the mesonephros in Triton throws much light on the general con- 

 dition of this organ in Urodeles. 



The urino-genital system of Salamandra generally, and of the 

 male particularly, is very interesting, since it shows an even more 

 primitive condition than is found in the Selachians in that the anterior 

 part of the kidney is less specialized for a purely genital function, and 

 retains clear evidence of its segmental nature. 



