198 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
bringen.” My first mode of Vierergruppen formation (Wilcox, *95, 
Diagrams 3-6, p. 10) would correspond to this condition (Figs. 7, 10). 
When all the chromatic substance of a segment has collected itself at 
the two ends of the segment, a “transverse division " has already taken 
place, so far as the chromatin is concerned, although the two masses are 
held in connection by means of linin fibres. 
The bodies at the ends of the spindles in Rückert’s Figures 14, 18, 
19^, and 29”, seem to me of rather doubtful nature. The evidence given 
is not sufficient to satisfy me that they are centrosomes, and of nuclear 
origin, as Rückert believes. Rückert (94, p. 337) combats Weismann’s 
idea that reduction is accomplished in both of the two divisions : “Ich 
meinerseits möchte dieselbe nicht geradezu als falsch bezeichnen, aber 
doch mindestens als unzureichend, weil sie auf die Bildung der Vierer- 
gruppen keine Rücksicht nimmt, sondern den Anschein erweckt als ob 
die sämmtlichen, für alle vier Enkelzellen zusammen bestimmten Chro- 
matinstiickchen von einander unabhängig wären und in beliebiger Grup- 
pierung in die erste Reifungsspindel eintreten könnten.” 
It thus seems as if Riickert considered the mere idea of chromosomes 
arising independently as too ridiculous for any one to maintain. I could 
wish he had explained why in his opinion it is unreasonable to suggest 
such a possibility. I believe that in the spermatogenesis of Caloptenus, 
at any rate, the chromosomes arise quite independently of one another 
in the prophases of the first maturation division, Furthermore, the 
chromosomes do not appear on the first maturation spindle in reduced 
number; but there has been instead a doubling. We must remember 
that each ring has the value of four chromosomes. 
Lee (05) has come to the conclusion that the problematic body of 
Platner and Zimmermann, the “ Zellkoppel,” arises from the remains of 
the interzonal filaments. The main results of his investigations, which 
were made upon the spermatogenesis of Helix sp., may best be stated in 
his own words (p. 46): ‘Dans les spermatogonies et les spermatocytes 
de l'Hélix, le fuseau caryocinétique persiste en général pendant sa regres- 
sion sous la forme d'un corps páteux, unissant les deux cellules issues de 
la cellule qui Pa formé. Ce corps est le corps problématique de Platner. 
Les corps ainsi formés par le fuseau regressif persistent normalement 
à travers plus d'une génération cellulaire ; et de la fusion de deux ou 
plusieurs de ces restes fusoriaux appartenant à des générations succes- 
gives, rósulte la formation d'une chaine de ponts fusoriaux reliant entre 
elles un nombre considérable de cellules. Ces chaines sont le ‘ Zoll- 
koppel’ ou ligament intercellulaire de Zimmermann.” 
