The nuclear components of the sex cells of four species of cockroaches. 503 
times seems to occupy a position at the blunter end of that body 
exactly as iu Periplaneta, but at otber times, it seems to invest the 
odd chromosome. A conspicuous vacuole is present in the plasmo- 
some, while the longitudinal split of the odd chromosome is often 
widened |iuto a comparatively wide space. The split closes up as 
the metaphase is reached. In the spermatids, the odd chromosome 
may readily be seen and along with it is a plasmosome which has 
arisen de novo in the daugther cells of the second division. As in 
the case of Periplaneta there is no continuity between the plasmo- 
some of one mitosis and that of the following onc. The spermato- 
genesis of this species is similar to that of Periplaneta and still 
more so to that of Blatta germanica , about to be described 1 ). The 
details of the various processes vary widely from those in Leucophcea. 
Blatta germanica L. 
The spermatogenesis of this species has been reported by Stevens 
f05) and by Wassilieff ('07) and the reader is referred to these 
publications for an account of the behavior of the sex cells. The 
writer has been able to corroborate the account of Stevens in all 
particulars with the single exception of the "extra-nuclear” chroma- 
tin, figured in her plate Y, figure 150. The writer has examined 
bis material in several stains and is certain that there are no bodies 
in the cytoplasm of any stage which show chromatin characters. The 
stage in which Stevens finds this cytoplasmic chromatin is an early 
spermatid, where the plasmosome takes up a position similar iu all 
respects to that body in the case of Periplaneta and as far as the 
observations of the writer go, there is no difference in the behavior 
of the plasmosome in these two species. 
With the description of Wassilieff, there are certain points of 
difference. Thus, the history of the nucleoli of the spermatogonia 
as given by that observer does not coincide with the observations of 
the preseht writer. 
Wassilieff’s description of the nucleoli of the spermatogonia 
is as follows; "Sehr interessant ist der Bau des Nucleolus. Er be- 
steht aus zwei Teilen: der eine Teil ist dunkler (wahrscheinlich chro- 
matisch) und kugelförmig und der andre heller und halbkugelförmig. 
Diese zwei Teile sind durch einen dunklen Strang verbunden, welcher 
b These two forrns have until recently been referred to the same genus, 
Blatta. 
