x MODES OF DESTRUCTION OF B. PESTIS 287 



Table I 



Positive sign means growth, negative sign means absence of 

 growth, after medication. 



Experiment 4. — This experiment is a control to the preceding 

 experiments with Staphylococcus aureus, and serves to compare the 

 effect of the disinfectant when used on a culture of the microbe in 

 watery emulsion. 



Of a 48 hours' agar active culture of Staphylococcus aureus 

 added to sterile distilled water, sufficient to form slight but distinct 

 turbidity. 



One loop of emulsion brought forth on agar an almost confluent 

 mass of Staphylococcus aureus. 



a. To 50 ccm. of the staphylococcus emulsion added 0'1 ccm. 

 izal, 1 in 500. 



b. To 60 ccm. of the staphylococcus emulsion added 0*1 ccm. 

 izal, 1 in 600. 



c. To 75 ccm. of the staphylococcus emulsion added 0*1 ccm. 

 izal, 1 in 750. 



After 5 minutes' exposure, made with 3 loops 1 agar and 1 broth 

 culture, incubation at 37° C, with result as follows : — 



a. 1 in 500, 5 minutes' exposure : no growth in either tube. 



b. 1 in 600, 5 minutes' exposure : no growth in either tube. 



c. 1 in 750, 5 minutes' exposure: agar shows 18 colonies. 

 Broth uniformly turbid with Staphylococcus aureus. 

 Table II. summarises the preceding results : — 



Table 



