50 PREVIOUS INVESTIGATIONS UPON ANIMALS 



ably altered bj^ a radiation of 36 hours then moved more slowly, and, 

 after four to seven days of exposure, gradually swelled up and dis- 

 integrated. In preserved specimens the macro-nucleus appeared 

 swollen, and deeply staining, and Dr. Zuelzer suggests that the 

 greater resistance of the chlorophyll-containing organism is possibly 

 due to an inhibition of the injurious effects of the rays by the oxygen 

 given off by the chlorophyll in the presence of light. 



The source of this suggestion of Dr. Zuelzer's was the work of 

 Hertel,-** who studied the effect of waves of ultra-violet light on 

 organisms. He found that organisms that contain chlorophyll are 

 more resistant to the injurious effects of the ultra-violet rays of a 

 wave-length of 280 /in than the chlorophylless organisms. The pro- 

 toplasmic streaming in cells of Elodea {Philotria) was retarded more 

 promptly in the dark than in light, though darkness in itself, at least 

 within one hour, does not affect the process. Illuminated leaves 

 were not affected as readily as those not illuminated, and Paramoe- 

 ciiim hursa7-ia Ehrenberg, which contains chlorophyll, was less sen- 

 sitive in light than species without chlorophyll. Hertel thinks that 

 the oxygen given off in the light by photosynthetic processes inhibits 

 the injurious effects of the ultra-violet rays. He further found that 

 the rays accelerate and favor the decomposition of hydrogen peroxide 

 when that process has been started by a catalyzing body, and finally 

 concludes that the effects of the rays on the living cell are due to this 

 influence on the proportion and distribution of oxygen in the cell. 

 Hertel's results with hydrogen peroxide possess added interest in 

 light of the studies of Neilson and Brown ^^ on the effects of ions on 

 the decomposition of hydrogen peroxide by platinum black. The 

 cation has an inhibiting or depressing effect, the anion an acceler- 

 ating influence. In these experiments solutions of 22 different salts 

 of sodium, and of nine different chlorides were used, with concentra- 

 tions of from w/8 to n/<,i2. 



If it shall be determined, says Dr. Zuelzer, after referring to 

 Hertel's work, that ultra-violet rays, as well as those of radium, can 

 influence the metabolism of the cell by depriving it of oxygen, then the 

 results of Venenziani^^ may find here their explanation, ior the Opalina 

 ranariun with which he experimented, lives normally in a medium 

 (the intestine) poor in oxygen. Continuing, she says that the dis- 

 turbance of spermatogenesis and the killing of the spermatozoa in 

 healthy tissue, the quick destruction of the skin and of malign tumors 



