Cell Changes iii the Testis due to X Rays. 
265 
served by us only in spermatocytes of the first order in association 
with a similar change in the cytoplasm. It occurs after the 3rd day. 
In relation to division the following changes occur in the nucleus: 
1. multiple and irregulär mitoses; 2. amitotic division. 
1. The former occur only in spermatocytes of the first order and 
are met with at the end of 24 hours after the application of X rays. The 
chromosomes are not usually distinctively somatic or heterotypical in 
character; occasionally they resemble, though not very closely, homo- 
type chromosomes. The distribution of the chromosomes on the spindle 
is unequal, some appear to be imperfectly attached to spindle fibres, 
and some are not connected with any of the spindles, but lie free in the 
cytoplasm. 
2. Amitotic division is marked in the cells of Sertoli; it is seen 
after the 7th day, and is usually indicated by the appearance of one or 
more deep clefts in the nucleus. Occasionally amitotic division is seen 
in spermatocytes of the second order; it has been observed at the end 
of twenty four hours. 
Nucleolus. No definite changes in the nucleolus, which is normally 
recognizable in cells of Sertoli and in spermatocytes of the first order, 
but not in spermatocytes of the second order or in spermatids, have been 
observed by us after the application of X rays. 
Intranuclear body. This is frequently affected by the action 
of X rays upon the spermatocytes of the first order, becoming enlarged, 
elongated and surrounded by a larger clear space than normal, the latter 
often becoming converted into a vacuole of considerable size. This change 
was observed between the 4th and 7th days after exposure to X rays. 
Chromatoid body. This cell constituent is an obtrusive feature 
of young spermatids, especially of those containing vacuoles, in which 
instead of a single lobulated mass there is sometimes a group of two or 
four, or sometimes more, smaller masses which otherwise do not present 
any marked difference in aspect from the normal. It is not clear that 
the chromatoid masses undergo any real increase in number or other 
change as the result of X rays. No chromatoid bodies are recognizable 
in the spermatocytes of the first order ; but in multivacuolated or multi- 
nucleated cells such bodies may be found in various situations in the 
cell masses. 
Archoplasmic vesicle. Enlargement of the archoplasmic vesicle 
of the young spermatid follows the application of X rays, first making 
its appearance after the third day. The enlargement causes indentation 
of the nucleus, which, as the vesicle continues to increase in size becomes 
Archiv f. Zellforschung. VII. 18 
