IRRADIATION OF LIVING PROTOPLASM 645 



granules within the cell." Various types of leucocytes differ, but in 

 general liquefaction is followed by coagulation. This may involve 

 disappearance of granules, and in fibroblasts there is a very striking 

 vacuolization of the protoplasm. In most types of leucocytes the fat 

 globules increase in size and number. All these phenomena are the very 

 ones described by other authors as characteristic effects of ultra-violet or 

 roentgen radiation. Unfortunately, however, Earle could not be certain 

 that the appearances he noted in leucocytes and fibroblasts were really 

 due to a direct action of the light on the cells in question. In the case 

 of both leucocytes and fibroblasts, the presence of erythrocytes seemed 

 to play an important role. The red blood cells are affected by the light 

 more readily than the leucocytes, and it is quite possible that substances 

 released from them are in large measure responsible for the effects 

 observed in the other types of cells. Red blood cells are hemolyzed by 

 light rays, an effect which seems to be due in large measure to an action 

 on hemoglobin (225). 



If the changes in leucocytes produced by illumination of blood are 

 due to degenerative substances emerging from injured erythrocytes, this 

 fact may be correlated with the theory that the action of roentgen rays 

 is in large measure due to injury substances, or necrohormones (cf. 

 Caspari, 55). 



» 



ULTRA-VIOLET RAYS 



In interpreting the action of ultra-violet rays on protoplasm, various 

 authors have stressed the fact that such rays may cause a coagulation of 

 proteins. The effect of radiation on proteins is discussed in another 

 section of this book (cf. Clark, pages 303-322). As pointed out pre- 

 viously, the "living colloid" is a much more complicated system than a 

 protein solution. We shall here confine our attention to living 

 protoplasm. 



Virtually none of the authors whom we shall consider has reported the 

 intensity used. Indeed, for the type of experiment usually performed 

 this does not seem entirely possible at present; the International Com- 

 mittee for the Measurement of Ultra-violet Light has recently decided 

 that no physical method of measurement that has yet been proposed will 

 permit accurate comparison of doses from different lamps {see British 

 Journal of Radiology 7 : 119. 1934). 



Working on the theory that ultra-violet rays produced an effect by 

 coagulating protein and that this effect varied with the pH (cf. Clark, 

 63), O'Donnell (278) studied the response of fish chromatophores to 

 ultra-violet rays when the cells were bathed in solutions of varying pH. 

 She could detect no difference in one solution as compared with another, 

 and hence could fuid no support for her simple theory. 



