6 Charles Russell Bardeen 



3 In the period of the finer diff'erentiation of the organs (func- 

 tional development of Roux) the primary effect of exposure 

 appears to be on the blood vessels, the tissues suffering because of 

 the effects on the blood vessels. 



G. Bohn,'^ who studied the effects of radium rays on the eggs 

 and larvae of the frog and turtle, found that if growth is slow 

 exposure to radium rays prevents the attainment of full size; if rapid 

 and associated with tissue differentiation, radium causes degenera- 

 tion of the tissues and although at first accelerating, ultimately 

 stops development. He considers that everything leads one to 

 think that the rays of radium affect the chromatine because it is 

 from the activity of this substance that there results assimilation 

 and growth. 



The action of the Roentgen rays on the hen's egg has been 

 studied by Gilman and Baetjer." These investigators found a 

 preliminary period of accelerated development followed by retard- 

 ation of development and the production of abnormal embryos. 

 J. Tur^^ studied the action of radium rays on developing hen's eggs 

 and obtained various deformities. He found the embryonic area 

 of the germinal disc more sensitive to the rays than the periphery 

 and obtained some germinal discs without embryos. He found 

 the cells of the ectoderm more easily affected than the yolk cells. 

 G. Schwarz," on the other hand, from his experiments on the action 

 of radium rays on the hen's egg, concludes that the action of the 

 rays is due to a decomposition similar to that of a dry distillation 

 brought about in the albumenoid bodies of the cell. He explains 

 the effect of the rays on rapidly growing tissue as due to their 

 special power to decompose lecithin. Perthes'^ found that the 

 wing of a chick exposed to radium rays was checked in its develop- 

 ment. 



The experiments with radium and Roentgen rays on plants, 

 invertebrates and the lower vertebrates, though of great scientific 



2*G. Bohn: Op. cit. 



^^Gilman and Baetjer: Op. cit. 



^^J. Tur: Comptes Reudus des Seances de la Society de Biologie, t. Ivii, 1904. 



^""G. Schwarz: Archiv f. gesammte Physiologie, C. 532, 1903. 



^^Perthes: Archiv f. klin. Chirurgie, Ixxi, 1903. 



