260 
J. 0. Wakelin Barratt and G. Arnold 
revealed by a diffuse cloudiness of botli cytoplasm and nucleoplasm; 
it is however more readily observed in stained specimens, basic dyes 
being taken up readily, while acid dyes are without effect. In spermato- 
cytes of tbe first ordcr in which necrosis is not so marked as to prevent 
Identification additional changes may be recognizable. One of the more 
common of such changes is contraction of the nucleus, sometimes marked, 
accompanying contraction of the cytoplasm (Figs. 15 and 17). Disappear- 
ance of the nuclear membrane is frequent (Fig. 15) and the spireme, which 
stains feeblv (Fig. 17) may become irregularly contracted into one or 
more portions. 
Necrotic change may also affect spermatocytes of the first order 
which are undergoing mitosis (Fig. 16). In such cases the necrotic cyto- 
plasm contains darkly staining granules and masses, some of which can 
be recognized to be more or less altered cliromosomes. A certain amount 
of shrinkage of the cell is not uncommon. 
Non-necrotic changes after the applieation of X rays are frequently 
met with in spermatocytes of the first Order which are not dividing. The 
following are most common: enlargement of the clear space surrounding 
the intranuclear body (Fig. 14); appearance of intranuclear vacuoles not 
containing an intranuclear body. These changes have beeil frequently 
observed between the tliird and seventh days after exposure to X rays. 
The former change results in the formation of a vacuole which may occupy 
more than half the volume of the nucleus. In both forms of vacuole the 
nucleus becomes considerably compressed and thinned, staining darkly. 
The characters of tliese vacuoles are further considered in the next section. 
Another change observed with some frequency is thinning of the 
spireme. It is not unfrequcntly attended with otlier changes, in parti- 
cular, necrosis (cp. Fig. 17). 
Non-necrotic changes also affect dividing spermatocytes of the first 
order, assuming the form of multipolar mitoses and abnormal bipolar 
mitoses. 
Multipolar mitoses (Fig. 19) are seen only at the end of twenty four 
hours. The number of poles generally varies between three and four. 
The number of spindles, which are frequently of unequal size, varies 
from two to four. In some cases common poles are seen, the number 
of such ranging from one to three. It will thus be readily understood 
that some of the figures produced are difficult to analyse. The spindles, 
which present a disordercd arrangement, are offen well defined, the spindle 
fibres being in many cases exceedingly distinct. Well defined centro- 
somes may be met with at the poles of the spindles. The cliromosomes, 
