Pseudo-Reduction in the Oögenesis of Allolobophora foetida. 
157 
Support of Popoff’s rcsults and conclusions. In referring to Gkegoike’s 
criticism of Popoff’s work he says, »Was nun Gkegoires Einwände be- 
züglich der Eibildung betrifft, so stimme ich w'enig mit ihm überein. Er 
macht die gleichen Punkte geltend wie bei der Spermatogenese, obwohl 
hier zwei ganz verschiedene Erscheinungen scharf zu trennen sind« (p.393). 
Büchner however, did not succeed in finding the stages demanded 
by Gregoire as necessary to sustain Popoff’s Claim that the post growth 
chromosonies are new formations, and it is just at this point that Ällolo- 
bophora gives the necessary evidence (photos 13 to 19). 
Photo 7 show's a common form of the leptotene stage — the excee- 
dingly fine threads are twisted and tangled and offen the contraction of 
the chromatin progresses so far as to prevent its differentiation from the 
nucleolus — the tw'o structures being almost fused. The term synapsis 
is frequently used for this stage as well as for the one in which the biva- 
lents first appear. Typically a nucleolus is present at these stages (Photo 7). 
In those cases however, in which the threads are pushed apart and spread 
over a larger area, the nucleolus is sometimes destroyed (Photos 6 and 9). 
Photo 8 is a typical young resting oöcyte showüng a nucleolus and 
chromatin net-work. The position of these eggs in the ovary clearly iu- 
dicates that they are the young oöcytes and all transitional sizes can be 
found between these cells and those which have reached their maximum 
size at the distal end of the ovary (text-fig.) 
From this stage until the eggs have reached their maximum growTh 
there is no evidence whatever of the persistence of the chromosomes and 
those who would claim that the chromosomes persist through these stages 
in Allolobophora foetida would, as Fick says, be “dealing wth an hypo- 
thesis and not a fact” (Fick 07). 
Photo 10 shows the nucleus of a much larger oöcyte witli a typical 
clu'omatin reticulum — the nucleolus is present though faintly stained. 
Büchner supports Wassilieff in observing that only part of the substance of the 
chromatin nucleolus gives rise to the accessory chromosome. 
This would seem to indicate that the chromosomes in question are evolved from 
a nucleolar mass of chromatin, thus homologizing this structure with the cases in which 
it is claimed all the chromosomes are evolved from a large nucleolus, leaving a nucleolar 
residue after the chromosomes are formed. In Euschistus we find cases in wldch both 
the idio-chromosomes and a chromatin nucleolus are present at the same time. Such 
facts added to those cases in wldch the size relations of the chromatin nucleolus do 
not agree with those of the idio-chromosomes, raise the question as to the identity 
of the two structures, though these facts would not conflict with homologizing the 
chromatin nucleolus with the nucleolus which in some forms is said to give rise to all 
the chromosomes. 
