IRRADIATION OF LIVING PROTOPLASM 655 



reactions which tend to bring the protoplasm back to normal. Perhaps, 

 too, various types of vacuoles may be formed. 



In the discussion of the effects of ultra-violet radiation, evidence was 

 presented to show that the initial effect of the ultra-violet rays was to 

 cause a release of calcium from the cortex of the cell. Stvidents of roent- 

 gen rays and radium have demonstrated a release of calcium from the 

 cell by chemical means. The work of Rochlin-Gleichgewicht (317) has 

 already been noted. Adler and Wiederhold (3) find that following 

 exposure to roentgen rays (1000 to 5000 r), the calcium content of the 

 skin of rabbits may decrease as much as 57 per cent. Apparently there 

 is an escape from other tissues as well as the skin, and Benassi (21) found 

 an increase in blood calcium after exposure of rabbits to X-rays (cf. 6, 

 323). However, Kroetz (203) and Adler and Wiederhold (3) find a 

 decrease in serum calcium following irradiation. The divergence is 

 doubtless due to the fact that following X-ray treatment there is a huge 

 increase in calcium eliminated from the body (K. and M. Adler, 2a). 

 These authors conclude that the tissues must give off calcium following 

 irradiation. That this release is from the cell cortex is indicated by 

 the fact that there is apparently an increase in permeability following 

 treatment with roentgen rays or radium (see section of this paper on 

 Permeability), and also by the fact that following radiation, there is 

 a general weakening of the outer membrane of the cell. Various authors 

 describe rupture of the cell membrane following treatment with roentgen 

 rays or radium, in Pelomyxa (399) and in yeast cells, both following 

 radium treatment (266), and in bacteria after exposure to X-rays (181). 

 As in the case of ultra-violet rays, we assume this weakening of the 

 cortex or membrane of the cell to be associated with a loss of calcium, 

 although other factors, such as an accumulation of fluid beneath the 

 membrane, or a general increase in cell volume (Nadson, 265, 266) may 

 also play a role. 



In our attempt to find a general scheme which will explain the effects of 

 all types of radiation on protoplasm, we have examined the literature from 

 one angle rather than from all sides. We have also presented our theory 

 as though it covered all the facts. This it can scarcely do. Protoplasm 

 is extremely complex, both from a chemical and from a colloid chemical 

 standpoint. The effects of radiation cannot be fitted into too simple a 

 picture. 



One of the most interesting observations we have not as yet con- 

 sidered is that of Nadson (266). He found that radium caused an 

 increase in the number and size of fat droplets in exposed yeast cells. 

 The same changes are produced by roentgen rays and by ultra-violet 

 (Nadson and Stern, 271). Rochlin-Gleichgewicht also states that the 

 final effect of radium emanation on cells of Elodea and Pterygophyllum 

 is to cause a breakdown of protoplasmic fat protein combinations into 



