1904] On the Action of Radium on Micro-organisms. 379 



The control at this time showed practically the same number of bacteria a3 were 

 present originally. 



One of a Series of Experiments with Spirillum cholera? Asiatic®. 



Before exposure to radium, 47,000 bacteria were present in a platinum loopful 

 of emulsion. After 3 hours' exposure to radium, 2100 were left alive per 

 platinum loopful, while no bacteria survived an exposure of 6 hours. 



The control preparation showed at this time practically no decrease in the 

 number of bacteria originally present. 



Results of Experiments with Bacteria containing Spores. 



Bacteria containing spores were by far the most resistant to the 

 germicidal action of radium of any micro-organisms used in these 

 experiments, for they were not killed by less than 72 hours' exposure. 

 This corresponds with the time given by R. Pf eiffer and E. Friedberger* 

 as necessary for the killing of spores by the emanations of the radium 

 used by them. 



The following are examples of experiments with these micro- 

 organisms : — 



One of a Series of Experiments with B. mesentericus vulgatus (Sporing). 



Immediately before exposure to radium the preparation showed 170,000 micro- 

 organisms per platinum loopful of emulsion. After 48 hours' exposure this 

 number had decreased to 260, and at the end of 72 hours all micro-organisms per 

 platinum loopful had been killed. 



The control preparation showed practically no decrease in the number of micro- 

 organisms at the end of 72 hours. 



One of a Series of Experiments ivith B. anthracis (Sporing). 



There were originally present 11,000 micro-organisms per platinum loopful. 

 After 48 hours' exposure to radium, 120 only were left alive, and at the end of 

 72 hours all micro-organisms per platinum loopful were killed. 



The control showed micro-organisms present in undiminished numbers at the 

 end of 72 hours. 



One of a Series of Experiments with B. tetani (Sporing). 



In the experiments with tetanus spores the actual numbers of micro-organisms 

 were not investigated, but only the presence or absence of living germs by means of 

 cultivations in the depth of sugar agar. 



After 48 hours' exposure to radium, the presence of living micro-organisms was 

 still evidenced, but after 72 hours' exposure no growth followed the inoculation of 

 a sugar agar tube. 



Thus in these experiments the non-sporebearing bacteria exhibited 

 the least resistance to the germicidal action of radium emanations, 

 withstanding exposure for 2 — 15 hours only. 



The resistance of the specific germ of vaccine was slightly in excess 



* 'Berl. Klin. Woch.,' July 13, 1903. 



