500 
Max Morse 
cytoplasm in which it lies is sloughecl off, it is carried away in tbis 
mass and raay be seen lying in the Collection of spermatozoa and 
sloughed off cytoplasmic masses in the interior of the cyst (fig. 54). 
The cytoplasmic masses tlow together to some extent and therefore, 
the appearance is given of a single mass of cytoplasm containing a 
number of plasmosomes. That the body called "plasmosome” here 
is of plastin nature, is readily seen in Auerbach preparations, 
being contrasted clearly with the green "heads” of the mature 
spermatozoön. 
It will be seen that the plasmosome caunot be confused with 
the odd chromosome or with any of the nuclear components of these 
stages. The writer has freqnently observed a plastin body in the 
"heads” of the spermatids (i. e., within the nuclear wall, but in such 
cases, the odd chromosome could be made out at the same time. 
This plastin body is probably the plasmosome of the re-formed nu- 
cleus and is doubtless comparable to that which is seen in the pro- 
phase of the other divisions. It is to be remembered that the plas- 
mosome, whose fate we have described in the spermatozoön, is that 
of the molher nucleus, which has given rise, by mitosis, to the nu- 
clens of the spermatid and spermatozoön. 
We have now completed our survey of the spermatogenesis of 
Periplaneta americana. We have found that a difference exists in 
the spermatogonial and oögonial chromosome numbers the former 
being one less than the latter. One chromosome maintains charac- 
teristic peculiarities throughout the maturation-period which permit it 
to be individually recognized at every period save in the metaphase 
and anaphase of the second spermatocvte division although even here, 
its preseuce is made evident by a difference in the number of chro- 
mosomes among the cells of this stage. We have traced the body 
into the spermatid and early spermatozoön, where it fades from view, 
along with the other chromatin structures of the nucleus. Throughout 
the various stages from the spermatogonia to the fully formed sperma- 
tozoön, it is therefore a constant nuclear component. 
At each mitosis, a plastin body, which sometimes assumes the 
shape and staining capacity of a chromosome in the ordinary stains 
used, arises de novo and at the end of each mitosis, it is invariably 
cast out into the cytoplasm where it disintegrates and disappears. 
We have seen that this body may easily be differentiated from the 
chromatin elements by the use of differential stains, notably the 
stain devised by Auerbach. 
