190 JOHN E. S. MOOEE. 



appearance of an initial spindle^ is not by any means neces- 

 sarily accompanied by any specific condition of the nucleus, 

 which may present the aspect of repose or active looping of its 

 constituent chromatin elements (cf. figs. 10, 22_, 11). 



I have often observed in the genital ridge of the salamander 

 the co-existence of a nearly full-sized spindle and a resting 

 nucleus (figs. 11, 22) ; and this peculiar retardation of the 

 looping of the chromatin, and ultimate disruption of the 

 nuclear membrane, presents many points of analogy, and may 

 be directly related, to the peculiar conditions Hermann de- 

 scribed as existing in the older spermatocytes. During any 

 given mitosis final equilibration is always reached by the 

 nucleus prior to that of the archoplasm and its related con- 

 stituents (figs. 16, 13, 14). 



In attempting to follow this cycle and its meaning, I have 

 chiefly concerned myself as heretofore with the cells constitut- 

 ing the embryonic genital ridge of the salamander. And from 

 what experience I have had with other tissues, I am inclined 

 to the belief that the conditions passed through elsewhere, will 

 be found to closely resemble those met with in these. 



In these cells of the genital ridge the archoplasm is always 

 most condensed and conspicuous, as I have said, in those 

 elements that have just completed their division, and whose 

 nuclei present the well-known horseshoe shape. These horse- 

 shoe nuclei are represented by previous authors^ with their 

 concavities looking directly away from one another, and with 

 the cornua of the nuclear figures in the plane of the paper. 



In the cells under examination I have never found this to 

 be the case, the planes containing the nuclear cornua being 

 parallel, and quite or nearly normal to an axis passing through 

 the extremities of the enclosed spindle and the central bodies. 

 These relationships existing between the planes of the 

 daughter-nuclei and the spindle axis are represented in 

 fig. 24. 



I have laid some stress on this point, as it is doubtful if the 



1 " Neue Beitrage zur Kenntniss der Zelle," Flcmming, ' Archiv fiir mikr. 

 Anat.,' Bd. xxxvii. 



