Abnormal Development of Toad Ova 7 



value, have been comparatively few in number. The practical 

 application of the rays in medicine has led to a much more exten- 

 sive series of observations on the effects of the rays on man and 

 mammals. 



The physiological effect of the Roentgen rays first noticed was 

 .the skin burn which after an intervening latent period usually 

 follows much exposure to the rays, and which may give rise to 

 great thickening of the skin or to ulceration. Similar lesions were 

 found to follow exposure to the salts of radium and like sub- 

 stances. Clincal experience as Well as experiments on various 

 mammals soon showed that the more deeply seated tissues, as 

 well as the skin, are affected by the rays, but that the different 

 tissues are variously .affected. Some tissues seem to be affected 

 directly, others seem to be affected only indirectly through alterna- 

 tions produced in the general metabolism or in the blood supply. 



General toxic effects following the exposure to the Roentgen 

 rays have been described in man by Seguy andOuenisset,^*'Walsh," 

 Kienbock,^*Baermann andLinser,^^ A. S. Warthin,^°D. Edsallj^^and 

 many others.^^ Similar effects have been described in many mam- 

 mals. Tarkhanoff^' experimented not only with several small 

 mammals (mice, rabbits and guinea pigs) but also upon frogs and 

 birds. He found that when long exposed the animals died with 

 symptoms of paralysis. Rodet and Bertin^* attributed the death of 

 animals exposed to X-rays to a meningo-myelitis. Numerous sub- 

 sequent experimenters have described toxic effects, paralytic symp- 

 toms and death in small mammals after prolonged exposure to the 

 Roentgen and radium rays. Danysz^^ was one of the first to study 

 this action of radium on small mammals. He found that a pro- 



^'Seguy and Quenisset: Bulletin de TAcad. des Sciences, 1897. 



"Walsh: British Med. Journal, 1897. 



^Kienbock: Wiener med. Presse, 1901. 



^'Baermann and Linser: Miinchener med. Wochenschrift, li, s. 918-994, 1904. 



^"A. S. Warthin, International Clinics, 15th series, vol. iv, p. 243, 1906. 



^'D, Edsall, Journal American Medical Association, xlvii, p. 1425, 1906. 



^^For a list of the literature on this subject, see Warthin, op. cit. 



^^Tarkhanoff: Gaz. degli ospedali, 1897. (Cited by Warthin.) 



^^Rodet and Bertin: Gaz. des Hop., 1898. (Cited by Warthin.) 



^^Danysz: Comptes Rendus de TAcad. des Sciences, Paris, 1903, 1904. 



