626 BIOLOGICAL EFFECTS OF RADIATION 



on gases — are even less relevant. We shall be concerned with the 

 physics of the living cells, and the effects upon these which radiations 

 share strictly in common with other external influences — a fact often 

 overlooked by the specialist in radiations. 



At the present time among radiation authorities there seems to be 

 scant appreciation of the fact that a physical study of protoplasm is at 

 all possible. Thus Rajewsky (299), after pointing out that most of the 

 radiation literature is concerned with end reactions and that what is 

 needed is some research on the "Grundvorgange," goes on to state that 

 with present techniques no direct information concerning the primary 

 effect of radiation on plant and animal cells is possible. He describes, 

 therefore, experiments on proteins. A similar point of view is main- 

 tained by Dyes (85). 



We shall insist emphatically that a knowledge of the effects of radia- 

 tions on proteins or other inanimate materials is of secondary importance 

 to the knowledge of the effects of radiations on living protoplasm. Over 

 and over again, direct study of the colloid chemistry of protoplasm has 

 shown that the living substance is unique in its behavior toward physical 

 and chemical agents (Heilbrunn, 136). A student of blood clotting 

 would scarcely expect to arrive at a solution of his problem by studying 

 the colloidal properties of egg albumen and gelatin. The behavior of the 

 blood is vastly different, we are certain, from that of a simple protein, and 

 it is complicated by the presence of little-known substances exceedingly 

 potent in their effects on coagulation. We can scarcely hope, therefore, 

 for success in treating protoplasm, which is at least as complex as blood, 

 as though it were a simple protein. We stress this analogy, for on the 

 one hand protoplasm in its power of sudden gelation shows a colloid- 

 chemical similarity to blood (Heilbrunn, 136), and on the other hand, the 

 various substances involved in blood clotting are all apparently present 

 in tissue cells (Kraus and Fuchs, 200, 201, Fischer, 100). Inanimate 

 proteins can, therefore, scarcely provide a satisfactory model for the 

 living cell. 



Some radiologists have emphasized the fact that isolated cells are less 

 sensitive to roentgen rays than cells in mass (see Glocker and Reuss, 121), 

 and they insist that it is unwise to consider experiments on isolated cells. 

 As far as we can judge, however, it seems certain that the effects on 

 single cells are essentially the same as on cells in mass, although apparently 

 a larger dosage is necessary to affect them. One explanation for this 

 phenomenon, or rather one factor in the explanation, is the fact that 

 injured cells may very well have an indirect effect on cells in their neigh- 

 borhood, so that when a tissue is irradiated, the more sensitive cells 

 affect the whole mass. We shall return to this point later. But our 

 main interest is in the primary effect of radiation on the living proto- 

 plasm and this can be best studied in isolated cells. 



