Cell Changes in the Testis due to X Rays. 
259 
appearance of these cells not being apparent. Düring the period in 
which spermatogonia are recognizable we have not, however, after careful 
search encountered any division figures, from which it follows that mitosis 
ceases early after X ray injury. In this way the rapid diminution of the 
numbex of spermatocytes of the first order about to be described, obser- 
vable after X radiation of moderate intensity, is in part explained. 
Observations of changes occurring in spermatogonia after exposure 
of the testis to X rays is attended with some difficulty, owing to the 
circumstance that on the one hand these cells (and in somewhat lesser 
degree spermatocytes of the second order) are, in comparison with sperma- 
tocytes of the first order and spermatids, relatively few, a somewhat 
extended examination of a large number of sections being therefore 
necessitated and, on the other hand the size of the spermatogonia is 
small and tlieir characters are not very pronounced (cp. Fig. 2), so that 
their Identification, when somewhat altered, would not be readily effected. 
Spermatocytes of the first order. Düring the first few days 
following exposure to X rays marked changes develop in the spermato- 
cytes of the first order and as these cells are numerous and prominent 
the resulting alteration in the aspect of the tubule soon becomes obtrusive. 
The alterations observable in spermatocytes of the first order fall 
into two classes: that in which necrosis, revealed by changes presumably 
autolytic in cliaracter, takes place ; and that in which non-necrotic changes 
occur. The second dass is frequently met •with alone, but may also 
occur in association with necrotic change. When studying the slighter 
degrees of change it is necessary to remove one testis shortly before the 
application of X rays in order to obtain a criterion of the condition of 
the other testis. 
Necrosis of non-dividing spermatocytes of the first order is usually 
recognizable in slight degree in the seminiferous tubules after the third 
or fourth day following exposirre to X rays. Düring the first three days 
the amount and degree of necrosis sometimes did not exceed to any con- 
siderable extent that observable in the control testis removed before 
exposure. Between the third and ninth days large necrotic masses were 
generally abundant. These in turn disappear after the ninth day; pre- 
sumably fluid is discharged into the lumen of the tubule by which the 
necrotic masses are carried aw T ay mechanically. The character of the 
necrotic change is better understood by a glance at Figs. 15 and 17 than 
by a verbal description. When this change is not too advanced the 
identity of the affected cell can frequently be determined by reference 
to the remains of the spireme. In the unstained condition necrosis is 
