654 BIOLOGICAL EFFECTS OF RADIATION 



cells so that different regions were at varying distances from the source. 

 Exposures of 1 mc. and higher showed the following picture: Directly 

 beneath the needle was a zone of necrosis in which cells were vacuolated 

 and apparently coagulated and in which calcium oxalate crystals could 

 be clearly distinguished. Beyond this, calcium oxalate crystals also 

 appeared in a so-called transition zone in which the protoplasm was 

 swollen and streaming movement had stopped. Farther still from the 

 needle was a zone in which the protoplasm looked normal but streaming 

 was accelerated. Beyond this the cells were normal. With lower doses 

 (0.08 to 0.3 mc), only the region beneath the needle is affected and this 

 shows increased streaming. All the results were ascribed to the softer 

 beta rays. Rochlin-Gleichgewicht attempts to interpret the results 

 in terms of conventional colloid chemistry. The first effect of radiation 

 is to increase the degree of dispersion and thus the protoplasmic viscosity 

 is lowered. Then there is an increased swelling of cytoplasmic colloids 

 which leads to an increase in viscosity; at this stage calcium oxalate 

 crystals appear. Finally denaturation leads to dehydration, and this to 

 vacuolization. To us this formal explanation does not seem so satis- 

 factory as the scheme outlined in the last section to explain the effects of 

 ultra-violet radiation. The results of Rochlin-Gleichgewicht fit in 

 beautifully with this scheme. 



It has been shown that roentgen rays and radium, like ultra-violet, 

 commonly produce a vacuolization of the protoplasm. Such a vacuoliza- 

 tion reaction is found not only after radiation but occurs in all types of 

 protoplasm following the most diverse treatments ; it is perhaps the most 

 distinctive characteristic of living substance. The importance of the 

 reaction was thoroughly emphasized by Heilbrunn (136) who regards it as 

 a specific colloid chemical reaction peculiar to living systems. The 

 relation of the reaction to calcium and the surface precipitation reaction 

 has already been pointed out. In Arhacia (sea urchin) egg protoplasm, 

 both vacuolization and surface precipitation reactions are preceded by a 

 breakdown of granular elements, and this breakdown is apparently 

 related causally to both types of reaction. In particular, the red pigment 

 granules of the Arhacia egg disappear. These red granules show all the 

 reactions of mitochondria and may be considered as such. It is not 

 surprising therefore to note that various cytologists have found that 

 radiation has a destructive effect on mitochondria and other formed 

 elements of the cytoplasm (cf. 168, 270, 379, 380). Such a breakdown of 

 mitochondria, granules, etc., may well represent a first stage in the clot- 

 ting or vacuolization process. 



The vacuolization reaction as it occurs in many types of protoplasm 

 is but little understood. Relatively few workers have examined it 

 experimentally. Doubtless it is a very complicated reaction, or series of 

 reactions, and presumably, in its early stages at Least, it involves counter- 



