244 
J. 0. Wakelin Barratt and G. Arnold 
growth of the cells of the seminiferous tubules have been studied with 
a degree of tlioroughness and precision of detail, which is unequalled in 
the case of any other kind of ceU. In carrying out tliis investigation 
it was decided to direct attention almost exclusively to the direct effect 
of the rays, not making more than a brief reference to such non-specific 
changes of a purely reparative character as may be produced at a later 
date in the connective tissue framework of the organ. 
The animal selected for the purpose of this research was the rat, it 
having been found in the course of some preliminary experiments that 
this rodent is more readily dealt with and more easily kept alive for long 
periods of time than the other animals, chiefly rabbits and guinea-pigs, 
which were employed in the earlier period of investigation. The choice 
of the rat was also in part determined by the fact that the normal changes 
occurring in the seminiferous tubule liave been somewhat exhaustively 
studied in this animal (compare p. 246). 
Literature. 
The literature of the changes produced in the testis by the action 
of X rays is very scanty. The earliest investigations were made in 1903 
by Albers-Schönberg 1 ). Daily exposures of rabbits and guinea-pigs 
to the action of X rays for periods of 15 to 30 minutes were given. The 
skin of the rabbit was exposed at a distance of 17 cm from the X ray 
tube, a 24 inch coil with a slow working mercurv break being used. The 
tubes were moderately soft. Exposures amounting to 195 to 377 minutes 
produced sterility without any change in the sexual potency. The sterility 
was due to death of the spermatozoa (the contents of the seminiferous 
tubules being free from spermatozoa) and a condition of azoospermia 
with atrophv of the testis resulted. 
Frieben 2 ) found that after the repeated action of X rays the testes 
of rabbits and guinea-pigs became markedly diminished in size. reaching 
from one half to one third of their normal size. Xo other macroscopic 
change was observed. Upon microscopic examination the atrophy of 
the testis was found to be due to disappearance of the epithelium of the 
seminiferous tubules. Instead of the normal epithelial content, con- 
sisting of an abundance of sexual cells in various stages of development, 
!) Albers-Schönberg. Über eine bisher unbekannte Wirkung der Röntgen- 
strahlen auf den Organismus der Tiere. Münchener med. Wochenschrift 1903. S. 1859. 
2 ) Frieben. Hodenveränderungen bei Tieren nach Röntgenbestrahlungen. 
Münchener med. Wochenschrift 1903. S. 2295. 
