516 University of California Publications in Zoology [VOL. 11 



as to include this part only it could be distinguished with 

 extreme difficulty, if at all, from the preceding stage. 



Comparatively few of the cells examined exhibited the V- 

 figures when observed from the side, the greater number dis- 

 playing a Y-shaped arrangement of the threads in the vicinity 

 of the proximal pole, with the stem of the Y ending in the 

 immediate neighborhood of the sphere and the arms drawn out 

 into fine threads which are lost in the distal portion of the nucleus 

 (pi. 25, fig. 5). In the part of a section which contains sperma- 

 tocytes in this condition there is a gradual change from the V- 

 to the Y-figure; the cells characterized by the short-stemmed 

 Y-figures give place gradually to those in which a long-stemmed 

 figure predominates (pi. 25, figs. 6 and 7) ; and in the individual 

 nuclei there is considerable variation in the length of the struc- 

 ture from the free end to the fork. At times the thick threads 

 seem also to be double, but it is not possible to demonstrate this 

 condition in most cases. As the length of the stems of the Ys 

 increases the extent of the network diminishes. 



As can be easily imagined, it is practically impossible to 

 determine with accuracy in this stage the number of the V- and 

 Y-figures, and of the fine threads of which they are composed. 

 While the threads are perfectly clear in side views, they are 

 easily confused when seen from one end. Nevertheless, in one 

 nucleus corresponding to figure 4, so cut that the part containing 

 the pairing threads was viewed from the pole, a diagram indi- 

 cated the presence of twenty-six to thirty Vs and Ys, or, in other 

 words, of fifty-two to sixty threads; and in another case in a 

 stage like that shown in figure 6 there were clearly twenty-eight 

 thick threads (stems of Ys). 



This stage corresponds closely to that figured by Janssens 

 (1905) in his paper on the spermatogenesis of Batrachoseps and 

 designated by him the amphitene, in distinction to the preceding 

 or leptotene condition in which the fine threads are not united. 

 Much stress is placed upon it by the Schreiners (1906) in their 

 discussion of the spermatogenesis of Salamandra maculosa as 

 the stage in which a conjugation of the chromosomes takes place. 

 Many writers have overlooked it entirely, because, no doubt, of 

 its close resemblance to the leptotene period and the small number 



