THE URINO-GENITAL SYSTEM 285 



are doubtless applicable to Salamandra or to any other Urodele 

 possessing a multiple testis. The following is a summary of Hum- 

 phrey's conclusions. 



In the young mature male the testis consists of but a single lobe, 

 the multiple lobes being found only in older animals. The residual 

 spermatogonia in the portion of the testis which is emptied in any 

 given year, i.e. zone (iii) above, do not regenerate immediately, but 

 remain dormant for several months, while the functional testis for 

 the ensuing season (zone ii above) develops anterior to the emptied 

 zone. Then supposing the testis at this stage to consist of but a 

 single lobe, the spermatogonia of the posterior 'flagellum' become 

 active and give rise to spermatocytes, thus forming a secondary lobe 

 posterior to the first with the emptied dormant zone forming the 

 connecting strand. This second lobe shifts forwards each season in 

 a similar manner to the first, and eventually a third lobe may be 

 formed posterior to it, but when each lobe reaches the anterior end 

 of the genital tissue it just disappears and leaves the anterior 'flagel- 

 lum' of dormant spermatogonia. Thus a continual spermatogenic 

 wave moves slowly forwards along the genital strand, and the lobu- 

 lated appearance is simply the result of this movement combined 

 with the delayed regeneration of the emptied zones. 



Spermatogenesis has been investigated by a number of workers, 

 notably von La Vallette St. George (1875), Flemming (1888), 

 Nicolas(i892), von Rath (1893), Rawitz (1895), Meves (1895-6), 

 and Champy (19 12). The haploid number of chromosomes is 12 

 and the diploid 24. 



The sperm itself has been the subject of investigations by Czermak 

 (1850), von Siebold (1850), and Retzius (1906). Although rela- 

 tively short when compared with some other Urodeles, e.g. Triton, 

 the sperm of Salamandra is long and the nucleus is filiform, while 

 the acrosome is hooked. The middle piece is quite short and of the 

 same diameter as the head. The flagellum bears on one side a crenate 

 membrane along which a sinuous wave is continuously passing, so 

 that it has been called the undulating membrane. The tail terminates 

 in a short filiform end piece. The undulating membrane of course 

 provides the means of locomotion. 



One hermaphrodite specimen has been described by Feistmantel 

 (1902) in which eggs were found in the testis. 



3. The Vasa Efferentia, &c. 



The sperms leave the testis through a series (4 or 5) of fine ducts 

 which pass through the mesorchium from the testis to the sexual 



