EFFECTS OF RAYS OF RADIUM ON PROTOPLASM 345 



amount of oxygen which is taken in and of carbon dioxide which 

 is given off is greatly increased. The agents concerned in the 

 utihzation of oxygen and in the production of carbon dioxide 

 are undoubtedly the intracellular enzymes which during division 

 are more active than during the resting period. Acceleration 

 of the normal metabolic processes must necessarily involve a 

 quickening of the enzyme action. In like manner, retardation 

 of those processes is connected with a slowing down of the activi- 

 ties of the enzymes. 



According to Gager ('08), ''The broadest, and at the same time 

 the most definite generalization warranted by the work done so 

 far is that the rays of radium act as a stimulus to metabolism. 

 If the stimulus ranges between minimum and optimum points, 

 all metabolic activities, whether constructive or destructive, 

 are accelerated; but if the stimulus increases from the optimum 

 toward the maximum point it becomes an over-stimulus, and all 

 metabolic activities are depressed and finally completely in- 

 hibited." The fact that enzymes may be accelerated or retarded 

 has been shown by Richards ('14 b) who states that an exposure 

 of two minutes to X-rays produces an acceleration in their 

 activity, while an exposure of more than five minutes causes a 

 retardation. If we assume that such reactions are duplicated 

 in the living cell we have a logical explanation for the phenomena 

 which have been described. 



The results of these experiments suggest further lines for re- 

 search. It has been shown that in the sea urchin the chromo- 

 somes are not all affected in a similar manner, for some are 

 evidently injured while others are not visibly changed. Payne 

 ('13) has pointed out that when the egg of Ascaris is moderately 

 stimulated, the chromosomes show marked differences in their 

 reaction to the treatment. After the egg has divided, it is found 

 that the chromatin of the sex cells is noticeably different from 

 that in the somatic cells. This indicates that the two kinds of 

 chromosomes are physically different, as Boveri has stated. 

 This point can be tested by studies on the reactions of the chro- 

 mosomes of those bugs in which the X chromosome can be 



