262 
J. 0. Wakelin Barratt and G. Arnold 
irregulär mitosis (Fig. 19) ; and amitosis (Fig. 21). The size of the multi- 
nucleate cells may exceed that of fully fonned spermatocytes of the 
first order or may be much less. In the latter case the cytoplasm in which 
the nuclei are embedded usually stains more deeply than in the former. 
The cytoplasm is arranged in an imperfect somewhat coarse network and 
sometimes, but not always, contains one or more chromatoid bodies. No 
archoplasm appears to be present in the cytoplasm. The nuclei are one to 
four or more in number. In size they exhibit great diversity, varying 
between 4 u and 16 /.i in diameter. They have a well defined nuclear mem- 
brane ; tlieir chromatin consists of granules of very varying size distributed 
on Strands of linin. It is doubtful if nucleoli or intranuclear bodies are 
present in the nuclei. Some of the larger nuclei are observed to present 
a certain resemblance to nuclei of spermatocytes of the second order; 
others, smaller in size, to nuclei of spermatids. 
Multivacuolate cell masses are more common than multinucleate 
cells and are met with between the 4th and 7th days after the application 
of X rays (Figs. 24 and 25). The vacuoles vary.in number from two 
to twelve or even more ; in size they ränge from 4 u to 12 u or more in dia- 
meter. The size of the whole cell mass may exceed that of a fully fonned 
spermatocyte of the first order. The larger vacuoles are completely or 
partially surrounded, as the Figures indicate, by darklv staining material, 
in this respect resembling respectively the intranuclear vacuoles described 
above (p. 260) and the archoplasmic vacuoles about to be described 
(p. 266). Further consideration of the mode of origin of these cells will 
however be more conveniently taken in the next section. The smaller 
vacuoles sometimes appear to be completely covered by more or less 
Condensed nuclear material, sometimes it is doubtful if a complete cover- 
ing is present. The cytoplasm in which the vacuoles are embedded usually 
stains somewhat darkly; it exhibits a variable number of dark granules 
and may be free from archoplasm. 
Spermatids. Young spermatids, before the head is formed, for 
example in a stage not far removed from that represented in Fig. 10, 
may undergo necrosis. Xecrosis may also occur when the head of the 
Spermatozoon is partly formed, that is to say in the stage shown in Fig. 11 
(Fig. 29). The first appearance of necrosis was observed on the 4th day 
after the application of X rays, and it was considerably marked by the 
9th day. It is characterized by general darkening, the aspect of the 
cytoplasm being more or less homogeneous, no definite retieulum being 
apparent; its appearance is therefore not markedly different from that 
of necrotic spermatocytes of the first order alreadv described. The 
