298 



SCIENCE 



[N. S. Vol. XLII. No. 1079 



which radioactivity affects organisms. Ac- 

 cording to Verworn a stimulus is "any 

 change in the external agencies that act 

 upon an organism." Are the rays of ra- 

 dium or X-rays comparable to the electric 

 current, for example, in the manner in 

 which they affect protoplasm? An experi- 

 ment was performed by the writer to gain 

 information on this point. A frog's leg 

 was set up as a muscle-nerve preparation; 

 when stimulated electrically it was found to 

 react normally. The nerve, and later the 

 muscle directly, were exposed to X-rays. 

 When the brush discharge was carefully 

 screened away from the preparation, the 

 X-rays were unable to cause any contrac- 

 tion, even of the slightest extent, as shown 

 on the drum of kymograph. This result 

 was obtained repeatedly. "While it gives 

 no information as to real nature of the stim- 

 ulus, it indicates that the stimulus of radio- 

 activity is not comparable in its effects 

 with that of the electric current. 



Gager has adapted Verworn 's biogen 

 hypothesis to explain the manner in which 

 radium rays act as a stimulus to organisms, 

 and to provide the mechanism by which the 

 stimulation may be supposed to operate. 

 A stimulus is any change in the external 

 agencies that act upon an organism. Me- 

 tabolism according to Verworn "depends 

 upon the continual destruction and contin- 

 ual reconstruction of a very labile chemical 

 compound, ' ' biogen, which ' ' develops at an 

 intermediate point in metabolism, and by 

 its construction and destruction compre- 

 hends the sum total of metabolism." It 

 is not a protein nor living, for a molecule 

 can not be alive. The ratio of construc- 

 tion and destruction of biogen molecules 

 under normal conditions of equilibrium is 



construction ^;^_ Therefore, "the irrita- 



destruction 



bility of living substance depends upon the 



lability of the biogen molecules. 



Now, Gager remarks : 



Both the dissimilatory and the assimilatory 

 phases of metabolism may be stimulated. The 

 degree of dissimilatory stimulation is, for equally 

 intense stimuli, dependent upon the following fac- 

 tors: 



(a) The degree of lability of the biogen molecule. 



(&) The rapidity of the process of restitution 



after the functional destruction of the 



(c) The absolute number of biogen molecules 



present. 



(d) The conditions of the propagation of the 



stimulation. 

 A dissimilatory stimulation, or depression, may 

 be brought about by influencing any one of these 

 individual factors. On the other hand, the degree 

 of assimilatory irritability is dependent upon: 

 (a) The quality of the raw material available for 



nutrition. 

 (6) The means for working up the raw material 



into a suitable form of elaborated matter, 

 (c) The quantity of suitable elaborated matter. 

 {d) The rapidity of the transformation of the 



elaborated matter from the reserve depots 



into the biogen molecules. 

 An assimilatory irritability or depression may 

 arise through influencing each of these individual 

 conditions. 



Badium rays, by acting on any one of the eight 

 factors enumerated above, may, therefore, excite 

 or depress processes of either assimilation or dis- 

 similation. 



Further, Gager points out the probability 

 that radium rays may not affect their stimu- 

 lation "by acting directly upon the biogen 

 molecules, or whatever the reality may be 

 that corresponds to this term, but by acting 

 upon other substances in the individual 

 cells, or by modifying some process either 

 preceding or following the elaboration of 

 the biogen molecule." The rays may pro- 

 duce their effect indirectly by acting upon 

 some non-vital constituent other than the 

 biogen, or upon some purely chemical proc- 

 ess. Thus does he conceive the mechanism 

 by which the rays produce the changes 

 which they effect on organic bodies. 



It will be seen that this elaborate con- 

 ception of the method by which the results 



