358 GENERAL DISCUSSION" 



jnst miilti-membranoiTs systems as well as the whole submicroscopical 

 architecture of the nucleus and cytoplasm are closely allied in the 

 maintenance of the order of metabolic processes and self-adjustment 

 to the most ''beneficial conditions of work". We have no doubt of the 

 connection between structural organization and function, but here my 

 purpose is to emphasize a most important thing — connection with 

 '■'contror' of cell function. It is obvious that the disorganization of the 

 structure caused by irradiation, must have the most distinct features 

 of an accelerating mechanism, if it is connected with the disorganiza- 

 tion of control. We drew these conclusions in our report (G. M. Frank, 

 A. D. Snezhko) paying attention to the rhythmical processes and to the 

 connection of this rhythm A\'itli the structural mobility. If one imagines, 

 though hypothetically, that not only a definite organization is neces- 

 sary, but also that continuous alteration of this organization with 

 time is a part of the controlling mechanism, then, as a backgi^ound to 

 that system it is easier to appreciate the more pernicious role of 

 structural damage, compared with a consideration of this structural 

 damage only in statistical terms. 



bacq: VI. Is the oxygen effect universal? A part of the damage caused 

 by ionizing radiation does not depend upon oxygen. 



GRAY : In one sense the answer can be negative. IVIany of the reactions 

 already investigated in regard to cell damage have been shown to 

 occur when the irradiation takes place in the complete absence of 

 oxygen. On the other hand, other injuries to cells and organisms are 

 augmented in the presence of oxygen during irradiation. It is very 

 important, however, to point out the nature of these injuries. The 

 oxygen effect is observed when studying (a) injury to the chromosomes, 

 (b) the inhibition of cell multiplication, (c) the frequency of mutation 

 in micro-organisms, (d) the inhibition of the synthesis of nucleic acids, 

 (e) the inhibition of the synthesis of adaptive enzymes, (f) the inhibition 

 of the reproduction of viruses inside bacilli. 



All these effects have common features, a study of which would help 

 radiobiologists to look into this problem. All the effects mentioned 

 above are in some way or another connected with the reduplication 

 of genetic material inside the cell. AMien bacteria die, as a result of 

 the introduction of radioactive phosphorus, the initial lesion occurs in 

 the chromosomes; it is sensitive to oxygen concentration. 



However, in regard to other physiological effects, in jmrticular in 

 regard to the permeal)ility and passage of ions through the cellular 

 membranes we have unfortunately very little information. 



