WILCOX: SPERMATOGENESIS. 25 
Diagram II. serves to represent the view of Häcker, Weismann, vom 
Rath, and others. The first division is here seen to be an equation di- 
vision. But none of these authors has offered any reliable criterion by 
which we may judge whether it is tho “sister idants” or the “ non-identi- 
cal idants " that are separated by the first division. They have presented 
no satisfactory evidence that in the same nucleus all groups undergo either 
a reduction division or an equation division. How are we certain that 
one group does not undergo a reduction division at the same time that 
another in the same nucleus passes through an equation division? This 
possibility, as shown in Diagram IIL, is not excluded.  Hücker (792, 
Fig. 22, and '93, Fig. 116) believes he has seen two examples where the 
non-identical idants were still in connection with each other after sepa- 
ration of the sister pairs in the formation of the first polar globule, but 
the figures are rather unsatisfactory. 
This discussion will, I hope, have made one thing clear : the abso- 
lute necessity of a knowledge of the origin of the Vierergruppen, in 
order to a proper interpretation of the reduction question. If Brauer's 
account of the origin of the Vierergruppen: be correct, there can be 
no reduction. If.Häcker and vom Rath have rightly described their 
origins, there is one, and only one, reduction. If my description of the 
ring formation be accurate, there may be two reductions. I am quite 
willing to grant that, as Brauer maintains, precocious preparations for 
both divisions are made in the prophases of the first spermatocyte di- 
vision. But Brauer maintains an origin for the groups of four, which 
determines that each group shall consist of four identical elements, and 
thus does away with Weismannian reduction, while I contend that, 
owing to the manner of their origin, all four elements may be differ- 
ent or unlike one another, and therefore that both divisions may be 
reductions. 
The fate of a Vierergruppe, according to the four views mentioned, 
may again be brought together in diagrammatic form for comparison. 
Brauer : — 
" a aa ala AA 
a aa ala ala 
Henking ; — 
a aa tb Ala 
b bb bb blb 
