378 



Dr. A. B. Green. 



[Apr. 11, 



after those of the experimental vaccines had been killed. The 

 following experiment may be related to explain in greater detail this 

 action of radium. 



'Experiment. 



On November 12, 1903, vaccine pulp was exposed to radium at 10 a.m. Portions 

 of this pulp were removed from the influence of the radium at the end of 2, 6, and 

 10 hours' exposure. Liquefied nutrient agar-agar tubes were inoculated with one 

 platinum loopful of each portion immediately k after its removal from the radium, 

 and plates were established in the usual way. The remainder of each portion was 

 inoculated on a calf on the following day, November 13. 



Control. 



Plates were similarly established from the control at 10 A.m. and 8 p.m. on 

 November 12, and the remainder of the vaccine was used for inoculating the calf 

 on the following day, November 13. 



On November 18, the experimental portion of vaccine exposed to radium for 

 2 hours had caused good vesiculation on the calf ; the portion exposed for 6 hours 

 caused very poor vesiculation, and the remaining portion exposed for 10 hours 

 caused no trace of vesiculation. 



The number of extraneous bacteria originally present in the vaccine were 1200 

 per platinum loopful of emulsion (the mixture of this emulsion has been previously 

 described). In the portion of vaccine exposed to radium for 2 hours the number 

 left alive was 1050 per platinum loopful ; in the portion exposed for 6 hours there 

 were fifty bacteria, and in the portion exposed for 10 hours there was no evidence 

 of living bacteria at all. 



On November 18 the control portion of the vaccine had caused good vesicula- 

 tion ; and the agar-agar plate poured at 8 p.m. on November 12 contained practi- 

 cally the same number of colonies of extraneous bacteria as were present in the 

 plate poured from the same vaccine at 10 A.M. on the same date. 



Results of Experiment with Non-sporeoearing Bacteria. 



All the non-sporebearing bacteria previously mentioned were killed 

 after exposure to radium for 2 — 14 hours. A description in detail of 

 the results of some of these experiments may be of use in illustrating 

 this germicidal action. 



One of a Series of Experiments with S. pyogenes aureus. 



Before exposure to radium, plate cultivations showed 84,000 bacteria present 

 per platinum loopful of emulsion. After exposure to radium for 6 hours, this 

 number had decreased to 31,000 ; at the end of 10 hours' exposure to 260, and at 

 the end of 14 hours' exposure no bacteria were left alive. 



At the end of 14 hours the control preparation showed bacteria alive in practi- 

 cally undiminished numbers. 



One of a Series of Experiments toith B. coli communis. 



Before exposure to radium, 75,000 bacteria were present per platinum loopful of 

 emulsion. After 3 hours' exposure this number was reduced to 3000, and after 

 6 hours' exposure all the bacteria were killed. 



