WILCOX : SPERMATOGENESIS. 15 



and were thus unprejudiced in favor of rings or Vierergruppen in mak- 

 ing their drawings. The older works will be mentioned first, and the 

 important works of Boveri ('90), Brauer ('93, '94), Hacker ('93), Hen- 

 king ('90, '91, '92), and vom Hath ('91% '92, '93), will be considered 

 later. 



Flemming ('87, pp. 444, 445) saw Vierergruppen in the Salamander. 

 Figures 46-50 of his paper show chromosomes arranged in groups of 

 four, the groups being scattered quite irregularly over the spindle, 

 much as vom Rath figures them in his latest paper ('93). Flem- 

 ming considered this arrangement as abnormal : " Sie [the group- 

 ing into fours] kann wohl in der That als eine Anomalie bezeichnet 

 werden, obwohl ich noch nichts darliber weiss ob aus den Folgestadien 

 etwas normales werden kann oder nicht, . . . es finden sich also Grup- 

 pen von je vier Kiigelchen von deuen je zwei aneinanderhangen. Diese 

 liegen anscheinend ganz regellos iiber die ganze Spindel hingestreut, 

 nur offenbar mit der Tendenz sich nach den Polen anzuhaufen." Vom 

 Rath calls attention to Flemming's explanation of these figures, and 

 holds, quite rightly, that the groups are moving, not as Flemming 

 imagined, toward the poles, but toward the equator, there to be separated 

 into bivalent dumb-bells. Flemming believes he finds a tendency to 

 irregularity in those spindles which bear four-grouped chromosomes, and 

 considers such irregular spindles as so many stages in the degeneration 

 of a bipolar spindle into a tripolar one. If with Flemming it is denied 

 that the groups of four occur in the regular course of development, it 

 must be concluded that these are degeneration stages. 



Platner ('86) has figured in Helix pomatia several stages of rings and 

 their division without so interpreting them. Figure 4 of his ai-ticle 

 "Ueberdie Entstehung des Nebenkerns," etc., shows very clearly the 

 ring condition previous to division. In his Figure 5 are groups of four 

 chromosomes. Figure 12 shows rings on the equator of a spindle, and 

 Figures 15-17 are metakinetic and dyaster stages, in which the spherical 

 chromosomes are coupled into dumb-bell figures and some of the dumb- 

 bells have rotated 90° and are ready for the second division, just as I 

 have seen them in Caloptenus. 



I would call attention also to the following cases drawn from the 

 literature of the subject : La Valette St. George ('85, Figs. 16, 17, '86, 

 Figs. 11, 21, 22), Zacharias ('87, Taf. VIII. and IX.), Kultschitzky ('88, 

 Fig. 3, and '88 a , Figs. 16, 17, 22), Caruoy ('85, '86, and 86 a ), Guignard 

 ('91), Baranetzky ('90, Figs. 23, 26, 40), Hermann ('89, Fig. 31), 

 Lukzanow ('89, Figs. 21, 23), Henking ('92, Figs. 101, 153, 190, 216, 



