52 
Franz Schräder 
contoiir. The chromosomes of the sister group reappear oiit of the diffuse 
condition and assume form and staining capacity sinülar to those just 
described, and from this point on no difference can any longer be seen 
in the two groups (fig. 24). The chromosomal masses in both groups 
break up at the same time and each containing vesicle then begins to 
elongate to form the head of the sperm (fig. 25 and 26). 
No detailed analysis of other cell components in the spermatid was 
made. The initial stages of the nebenkem are difficult to find, and stages 
such as fig. 22 are more or less rare. Somewhat later, ha^dng grown and 
attained its maximum dimensions, the nebenkem becomes very distinct. 
Each cell contains two such bodies which seem to have no constant or 
definite location in relation to the two nuclei (fig. 23). Through a process 
of condensation, each nebenkem is then considerably decreased in size 
and is stained with more intensity than during the earlier stages of its 
formation. The elongation of the two nuclei commences at about the 
time when the two nebenkeme are becoming Condensed. 
The size of the double spermatids was increased considerably up to 
the time when the maximum dimensions of each nebenkem were attained. 
However, during the condensation of the latter, together \\'ith the elongation 
of the nuclei, the cell once more becomes smaller until it has regained the 
dimensions observed immediately after the reduction division. 
The nebenkem seems to furnish the materials for the axial sheath, 
but this point could not be determined with certainty. The rest of the 
cytoplasm is simply sloughed off (fig. 39). The spermatozoa are characteri- 
zed by long attenuated heads and and comparatively short tails, and all 
are identical in appearance. No signs of degeneration could be found in 
the ripe cysts. 
A similar origin of two spermatozoa from a double spermatid seems 
to have been observed in Icerya purchasi by Pierantoni ('13). His account, 
however, is too brief to admit of a more detailed comparison, and no other 
point of sunilarity between that coccid and Pseudococcus exists in his 
description of the maturation phases. 
The important point in the history of the spermatid lies in the diffe- 
rential staining reactions of the two groups of chromosomes involved. It 
is the massed group which retains its affinity for the stain most tena- 
ciously, just as it was the massed group in the pro phases which first 
stained with great intensity. On the other hand, the loose group in the 
spermatid is the first to lose this affinity for the stain, and it is the loose 
group in the prophases that very gradually acquires the capacity for 
staining, and this some time after the massed group. This is a significant 
