54 
Franz Schräder 
chromosomes. This number seems to be variable, but lies in the neigh- 
borhood of thirty (fig. 47). Although the majority of cleaving cells may 
still be dividing in the interior of the egg, I have never found such giant 
cells anywhere but at the periphery, For a time I entertained the notion 
that the chromosome number in these cells might represent the true 
number, and that the ten chromosomes observed in other somatic cells and 
also in the germ cells are in reality Sammelchromosomen. This idea was 
discarded in the face of several objections. In the first place, the normal 
sister nuclei in the interior of such eggs contain chromosomes no larger 
than those seen in the giant cells. If the larger number in the latter 
arises by a brealdng up or fractionation of ten chromosomes, a decrease 
in the size of the chromosomes should be expected as a result of the process. 
Secondly such an hypothesis does not account for the exceptional size 
of the giant cells. A third objection arises from the fact that no trace 
of these cells was ever found in slightly later stages of development — for 
instance in early gastrulae. Finally it was discovered that their probable 
origin is a fusion of several normal cells. Evidently there is some dis- 
arrangement in the mitotic mechanism of such cells which perhaps does 
not admit of complete cytoplasmic division and results in a multiple 
number of chromosomes (fig. 48). This behavior, coupled with the fact 
that such figures are always encountered at the periphery of the egg, 
suggested the possibility that they might represent persisting polar bodies. 
But no evidence could be adduced for this somewhat unlikely hypothesis. 
The fact remains however that such numbers of chromosomes and size 
of cells are not typical. 
An attempt was made to determine whether the normal somatic 
cells Show any sexual differentiation. In cells of larvae in the first instars 
the evidence was not definite enough to admit of any conclusion. It is 
all the more remarkable that a difference is strikingly shown in certain 
tissues of larvae in the last two instars. In males at this stage, restmg 
cells — especially in the nervous tissue — constantly show a clump of 
densely staining chromatin as well as more lightly stained and flocculent 
chromatin scattered through the nucleus (fig. 50). In females, correspon- 
ding cells show the chromatin in flocculent masses with no Suggestion 
of clumping (fig. 51). Evidently then, the Separation of chromatin into 
two groups which has been described for the spermatocyte stages is mani- 
fested also in somatic cells of males. In the females on the other hand, 
no such grouping is at all apparent. 
Other stages in somatic prophases Support this conclusion. In the 
male one group of chromosomes becomes evolved in advance of the other. 
