x MODES OF DESTRUCTION OF B. PESTIS 285 



Experiments 



First Series. — Pus of Acute Abscess. 



Experiment 1. — Of pus and blood of an acute abscess of the 

 female breast, 1 ccm. was added to 49 ccm. of sterile distilled water 

 (1 in 50). 



One platinum loop yielded about 100 colonies of -Staphylococcus 

 aureus. 



Added to diluted pus 0*1 ccm. of izal well shaken up. This made, 

 therefore, 1 izal in 500. 



Cultures were made with 3 platinum loops for each tube after 

 5, 15, and 30 minutes with this result: — 



a. After 5 minutes: agar tube has 12 colonies of Staphylococcus 

 aureus ; broth- tube uniformly turbid. 



This broth-tube was subcultured, with the result that it proved a 

 pure culture of Staphylococcus aureus. 



b. After 1 5 minutes : on agar 2 colonies of Staphylococcus aureus ; 

 broth-tube uniformly turbid. 



Subculture proved this broth-tube to be a pure culture of Staphylo- 

 coccus aureus. 



c. After 30 minutes : on agar 2 colonies of Staphylococcus 

 aureus; broth -tube greatly retarded growth, only faintly turbid 

 after 3 days' incubation. 



Considering that a single loop of the diluted pus yielded before 

 the addition of the izal about 100 colonies of Staphylococcus aureus, 

 whereas 3 loops (same loop as used in control) yielded after 5 

 minutes' exposure to the izal only 12 colonies, the process of disinfec- 

 tion must be considered already after this short space of time of a 

 fair degree ; this is well shown in experiment c, after 30 minutes' 

 exposure, when 3 loops yielded only 2 colonies j that is to say, 

 of 300 microbes only 2 had survived. The broth -tube bears 

 witness to this, since the broth showed greatly retarded and scanty 

 growth. 



The result of this experiment 1 is, then, that izal 1 in 500 

 may for practical purposes be considered a fair, though not complete, 

 disinfectant for pus of acute abscess (Staphylococcus aureus) after 

 30 minutes' exposure. 



Experiment 2. — The same pus as above was used ; 1 ccm. of the 



