Cell Changes in the Testis (lue to X Ravs. 
261 
when situated on the spindles, are distributed to them in unequal numbers 
and are irregularly arranged, sometimes the majority of the chromosomes 
lying on one side of the spindle. Xot unfrequently some of the chromo- 
somes are imperfectly attached to the spindle fibres, and others, indivi- 
dnally or in groups, appear to be altogether outside the spindle fibres. 
The chromosomes, as a rule, do not present the nsual aspect of hetero- 
typical chromosomes, but are of irregulär form, some being ovoid. They 
are generally of small size and appear to be merely fragments of fully 
formed chromosomes. The nnmber of chromosomes on each spindle is 
greater than that observed on the normal heterotypical bipolar spindle. 
Xo archoplasmic masses can be seen. 
Abnormal bipolar mitoses are also seen at the end of twenty four 
homs; the chromosomes, which are more numerous and smaller than 
normal, being apparently fragmented, are very often collected to one side 
of the spindle and one or more of the chromosomes may lie free in the 
cell, not attached to any spindle fibres (cp. Fig. 16). 
Spermatocvtes of the second order. Owing to the relative 
fewness of these in relation to the other cells of the seminiferous tubules 
and partly perhaps owing to theh’ less striking aspect investigation of 
the effect of X rays npon spermatocytes of the second order is not readily 
carried out. These cells disappear within about five days after exposure 
to X rays but the mode of theh - disappearance is uncertain. We have 
not observed necrosis affecting these cells either in the non-dividing state 
or during homotype mitosis. The sole change the occurrence of which 
we have been so far able to recognize is amitosis, illustrated by Fig. 21, 
in which the nucleus is seen to be incompletely divided by one large and 
two small clefts. The Identification of this cell, it may be observed, is 
made chiefly by reference to the presence of the archoplasm and chromatoid 
body in the cytoplasm and the arrangement of chromatin in the nucleus. 
Amitosis was observed twenty four hours after the application of 
X rays. 
Before proceeding to describe the effect of X radiation upon sperma- 
tids it will be convenient at this stage to describe the cell masses which 
are met with in seminiferous tubules after exposure to X rays, but cannot 
strictlv be referred to any of the normal cell constituents of the semini- 
ferous tubule. These assume two forms : multinucleate and miütivacuolate 
cell masses. 
Multinucleate cells (Fig. 20). These were first seen on the third 
day, subsequently rapidly disappearing; they are on the whole rarely met 
with. Two modes of origin of multinucleate cells may be suggested: 
