56 R- R- HUMPHREY. 



from this region, a caudal germ-cell cord is again established as in 

 Fig. / ; at the posterior end of this cord, eventually, lobule regen- 

 eration begins and a third lobe (see Figs. 8 and 9) is produced in 

 exactly the same way as was the second. In this way multiple 

 testes of as many as five lobes may come into being, though this 

 number, I may add, has been found in but one specimen. Like- 

 wise, but one specimen with testes of four well-developed lobes has 

 been noted. 



The exact time interval that elapses between the first extrusion 

 of spermatozoa and the regeneration of the region they occupied 

 as a caudal second lobe has not been stated in the above descrip- 

 tion. As lobules emptied in autumn degenerate very slowly, and 

 the interstitial cells marking their former location persist even 

 until the following autumn, the time interval before the emptied 

 region is completely reduced to a simple germ-cell cord is approxi- 

 mately a year. The spermatogonia in this cord, it appears, do not 

 begin their development at any fixed time after the final disappear- 

 ance of the degenerated lobules, but may remain quiescent for sev- 

 eral months longer. Testes similar to those in Figs. 3 and 4 have 

 been taken from specimens killed in June. Judging from the 

 length of the caudal germ-cell cord as compared with that of the 

 functioning testis, the formation of the second lobe could not be 

 considered as having taken place in less than sixteen to eighteen 

 months after the region first matured germ cells. Since the tiny 

 caudal lobes found in June or July will contain only spermatogonia 

 during the current season, they will not ripen spermatozoa until the 

 end of the following summer. In short, the second lobe of a mul- 

 tiple testis may possibly come to full functional maturity only after 

 an interval of three years from the time its territory of the testis 

 first matured sex cells that is, in the animal's third season of 

 sexual activity. Since after the disappearance of the degenerating 

 lobules and interstitial cells there is no means of distinguishing 

 regions in the caudal germ-cell cord, it is doubtful whether the 

 exact time interval before lobule regeneration begins can be deter- 

 mined. It would appear, indeed, that this time varies in different 

 animals, since in males killed at the same time, with testes having 

 small second lobes developing, these lobes will vary considerably in 

 degree of development ; though, doubtless, they are all to be re- 



