258 
J. 0. Wakelin Barratt and G. Arnold 
in studving the less marked changes following X radiation of moderate 
intensity, to remove one testis for microscopical examination shortly 
before applying the rays to the other. In this way the risk of confusing 
preexisting changes with the effect of X radiation is avoided. 
Changes in the interstitial tissue. The chief change observable 
in the testis at the end of a week after prolonged exposure to X rays 
(when the gland has already become shrunken) is marked oedema, clear 
fluid exuding freely from a cut surface. Shght congestion is also observable. 
On microseopic examination at this period or at the end of a fort- 
night after the application of X rays no struetural change can be re- 
cognized in the intertubular stroma beyond some distension of the con- 
nective tissue spaces. The nuclei of the interstitial tissue are not in- 
creased in number or otherwise altered. Xo cell Infiltration has occurred 
and the bloodvessels are unchanged. 
Changes in the cells of the seminiferous tubules. Cells 
of Sertoli. The most marked changes are observed about fourteen 
days after prolonged exposure to X rays, when the seminal cells have 
been destroyed and the cells of Sertoli are greatly increased in number y 
the tubule being in the condition shown in Fig. 30. At this period the 
cytoplasm surrounding the nucleus is diminished in amount, presenting 
a ragged appearance with ill defined margins, exhibiting a very coarsely 
reticular, occasionally vacuolated, character and staining lightly (Fig. 13; 
compare this Figure with Fig. 1, in which a healthy cell of Sertoli is 
shown). The size of the nucleus is not much altered ; its margin is rounded 
and presents one or more longitudinal clefts, in particidar one large cleft 
extending completely across the nucleus being common. It contains 
coarse chromatin granules, some distributed on a faint linin network. 
The nucleolus is unaltered in aspect. The shreddy material seen in 
Figs. 30 and 31. which is usually regarded as consisting of the cytoplasm 
of Sertoli. is exceedingly abundant. This material cannot be recognized 
with certainty in healthy seminiferous tubules. 
At an early period the above changes are less marked. At the end 
of four days after exposure to X rays increase of the amount of shreddy 
material and of the number of the cells of Sertoli is recognizable with 
more or less difficulty, the seminal cells being at this period still present 
in large numbers. 
Spermatogonia. After moderately prolonged exposure to X radia- 
tion spermatogonia are usually recognizable for about three days. After 
the fourth day tliey cease to be recognizable. Düring this period we 
have not been able to observe necrotic or other change, the mode of dis- 
