Amitosis in thc Ovary of Protenor belfragei and a Study of the Chromatin Nucleolus. 207 
period it acts like a chromatin nucleolus in preserving a compact form 
and in continuing to take the saffranin stain with the use of the double 
stain of Hermann, while the other chromosomes take the violet stain” 
p. 178. In his figure 128 he clearly demonstrates a transverse constriction 
of the chromatin nucleolus (X-element) which he describes as “A single 
annular constriction or a clear connecting bridge of linin.” He adds, “This 
transverse constriction pointing to a bipartite nature would show that 
the chromosome X is bivalent.” 
As several investigators are convinced that the chromatin nucleolus 
represents something more than a persisting chromosome any evidence 
that points to its duplex nature is not without interest. We have there- 
fore photographed some of our preparations which demonstrate the bi- 
partite form of this structure and we can Support Montgomery’s obser- 
vations on this point. 
The constriction is clearly shown in plate XVI, photos 40 and 41 
(upper nucleus) and in photo 42 (more distinctly in the upper nucleus). 
In this paper we have nothing new to add to the accounts already 
given of the spermatogenesis of this form. We have reproduced only 
a few of our photographs of the male cells in Order to compare the chro- 
matin nucleolus in the spermatocytes with the chromatin nucleolus we 
have been able to demonstrate in the ovarian cells. 
Recently a few investigators have claimed that in the oögenesis of 
certain forms a chromatin nucleolus is present which they homologize 
to the chromatin nucleolus in the spermatogenesis of insects. 
Gutherz (1906) figures a young oöcycte of Pyrrhocoris (fig. 12) in 
which he demonstrates a true nucleolus as well as a chromatin nucleolus, 
homologizing the latter to the chromatin nucleolus of the spermatocytes. 
»Im Synapsisstadium sowohl des Spermio- als des Oocyten ist ein Chro- 
matinnucleolus vorhanden. « 
Wilson (1906) concludes that in the forms he has examined no 
chromatin nucleolus is present in the oöcytes at the period prior to the 
stages in which “the chromosomes spread througli the nuclear cavity, 
become looser in texture and finally give rise to a fine reticular structure”, 
he adds “I can, therefore, only state that no chromosome nucleolus is 
present in the contraction period of synapsis, or in the early growth period, 
and even though it be present in the later stage, which I think is very 
doubtful, a wide difference between the sexes would still exist in respect 
to the earlier period” pgs. 22 — 23. Wilson briefly mentions these facts 
without giving any figures to demonstrate his conclusions. 
In 1909 we demonstrated that in later stages of the germinal vesicles 
