14 Charles Russell Bardeen 



in the larvae exposed to radium emanation and preserved by 

 Schaper, any evidences of tissue degeneration such as follows 

 direct irradiation. 



The Roentgen rays and the rays emitted by radio-active sub- 

 stances are known to cause ionization of gases, to affect photo- 

 graphic plates, phosphorescent substances and glass. It seems 

 evident that they also modify the chemical nature of living bodies. 

 It is certain that in some instances, at least, as proved by Perthes^^ 

 Thies,^* Koernicke,'* and others, the cell nuclei are primarily 

 affected by the rays. An injury to nuclei of cells sufficient to 

 destroy the normal influence over metabolism would suffice to 

 account for all phenomena which have been observed. The special 

 destructive influence on cells undergoing rapid assimilation, multi- 

 plication and differentiation may be accounted for by the very 

 important role played by the nuclei in these processes and an 

 apparently greater susceptibility of the nuclei at such periods. The 

 recent important and suggestive paper of F. R. Lillie J'' on the ele- 

 mentary phenomena of embryonic development in Chaetopterus, 

 shows what an active part is performed by the nuclei of cells dur- 

 ing the early stages of embryonic development in furnishing sub- 

 stances to the cytoplasm and in turn assimilating substances from 

 the cytoplasm. While irradiation does not as a rule directly stop 

 the phenomena of mitosis it evidently severely alters the productive 

 activities of the nuclei of the cells and thus affects metabolism. 

 Irradiation may also possibly directly affect the cytoplasm and 

 intercellular substances. 



Thies^^ from a careful study of the action of radium rays on 

 the different mammalian tissues and organs comes to the conclu- 

 sion that all tissues suffer, although the elastic tissues are relatively 

 resistant. The adenoid tissues are the most susceptible. Other 

 very susceptible tissues are the epidermis, the intima of the blood 

 vessels, the parenchyma of the sexglands, voluntary muscle, white 



'^Perthes: Archiv f. klin. Chirurgie, Ixxi, 1903; Deutsche med. Wochenschrift, 1904. 

 '^Thies; Wirkung der Radiumstrahlen auf verschiedene Gewebe und Organe. Mitteil. aus deu 

 Grenzgebreden d. Medizin und Chirurgie, xiv, 1905. 



'^Koernicke: Berichte der deut. bot. Gesellschaft, 1904-oq. 

 ' Lillie; Jour, of Experimental Zoology, iii, pp. 154-263, 1906. 

 ''Thies: Op. cit. 



