SUSCEPTIBILITY OF AMPHIBIAN OVA TO X-RAYS 425 



tissues in which differential morphogenesis is not constant appear 

 in large part, at least, to be merely secondarily affected through 

 alterations produced in the general metabolism or blood supply 

 by the injuries produced in the actively reproductive tissues. 

 Toxic effects thus produced have been described in man and the 

 lower vertebrates by a large number of investigators. Several 

 of the smaller mammals have been killed by exposure to the rays.^ 

 Changes in the interior of the smaller blood vessels are frequently 

 described after exposure to the X rays. Whether these are pri- 

 marily due to the X raj^^s or are the secondary effect of injuries 

 produced in rapidly reproductive tissues is uncertain, Scholz 

 and many others believe that the X rays and radium may pro- 

 duce primary changes in the intima. CI. Regaud, on the other 

 hand has been able to produce extensive alterations in the seminal 

 epithelium without visible alterations in the blood vessels of the 

 testicles. 



The effects of the X rays on the testicles have been most care- 

 fully studied by CI. Regaud and his pupils to whom we likewise 

 owe an excellent review of the literature of the effects of the X 

 rays and of radium on the sex glands. (C. Regaud, '08). Most 

 of the work has been done on the testicles of the rat, guinea pig, 

 and rabbit, but enough has been done on other forms to indicate 

 that throughout the animal kingdom the seminal epithelium is 

 exceedingly sensitive to irradiation. In small mammals, such 

 as the rat, the effects are more rapid and complete than in larger 

 animals owing, apparently, to the smaller amount of filtration 

 of the rays by overlying tissues. The seminal epithelium is far 

 more sensitive than the epidermis so that in the smaller mammals 

 sterility may be produced without marked injury to the skin 

 (Bergonie et Tribondeau, '04). 



In the rat lesions in the seminal epithelium begin to become 

 manifest two or three days after irradiation and from this time 

 on they become more and more marked until at the end of the 

 3rd or 4th week the generative elements may completely dis- 

 appear. Regaud distinguishes two kinds of effects of irradiation, 



^For th(> literature on this subject see A. S. Warthin, 1906. 



