Cell Changes in the Testis due to X Rays. 
251 
same shreddy liglitly staining material which has just been described 
as present in the ultimate stage is also seen in smaller amount in this 
stage. The lumen of the tubule is completely occupied. Nuclei are present 
in somewhat greater numbers than in the ultimate stage. 
Under a higher magnification the shreddy material seen in the pen- 
ultimate stage is observed to be denser and slightly more granulär than 
in the succeeding stage. Numerous very small fatty granules appear to 
be embeddcd in its substance. The large fatty masses are mostly round 
in shape and exhibit various degrees of blackness when stained with 
osmic acid; they lie in the interspaces of the shreddy material. The 
nuclei of the cells of Sertoli do not differ from those seen in the ultimate 
stage. The outline of the cytoplasm surrounding these nuclei is indistinet. 
The basement membrane, it may be observed, presents no alteration 
from the normal in either the ultimate or penultimate stage. 
Normal changes taking place in the seminiferous tubules of the rat; 
• formation of spermatozoa by the cells of the seminiferous tubules; 
degeneration of seminal cells. 
In the previous section the ultimate changes resulting from the 
action of X rays have been set forth. Before proceeding to describe the 
mechanism of production of these changes it will be of assistance to the 
reader to trace as succinctly as possible the course of events, normally 
occurring in the seminiferous tubules, whose ultimate result is the pro- 
duction of spermatozoa. It is not proposed here to do more than give 
a very brief outline of these changes. 
Formation of spermatozoa in the seminiferous tubules. 
Spermatogenesis in the rat and many other mammals has been described 
with more or less completeness in numerous monographs, and the reader 
should consult these for details which the space at our disposal does not 
permit us to give. Special attention should be directed to the articles 
on this subject by von Ebner 1 ), Hermann 2 ), Lenhossek 3 ), Meves 4 ), 
!) v. Ebner, V. Zur Spermatogenese bei den Säugetieren. Arch. f. mikr. Anat. 
1888. Bd. XXXI. Nachtrag zur Spermatogenese bei den Säugetieren. Ibid. 1888. 
Bd. XXXI. Uber die Teilung der Spermatocyten bei den Säugetieren. Sitz. Ber. d. 
Akad. d. Wiss. Wien. Math. nat. \viss. Klasse. Abt, 3. 1899. Bd. CVIII. 
2 ) Hermann, F. Beiträge zur Histologie des Hodens. Arch. f. Anat. 1889. 
Bd. XXXIV. 
3 ) v. Lenhossek, M. Untersuchungen über Spermatogenese. Arch. f. mikr. 
Anat. 1898. Bd. LI. S. 215. 
4 ) Meves, Fr. Über Struktur und Histogenese der Samenfäden des Meerschwein- 
chens. Arch. f. mikr. Anat. 1899. Bd. LIV. S. 329. 
17 * 
