286 OMENTAL PLAGUE chap. 



pus was added to 39 ccm. of sterile distilled water (1 in 40), then 

 0*1 ccm. of the izal was added (1 in 400), well shaken, and cultures 

 were made as above after 5, 15, and 30 minutes on agar and in broth, 

 using 3 platinum loops for each tube. 

 The result was this : — 



a. After 5 minutes' exposure : on agar 1 5 colonies of Staphylo- 

 coccus aureus ; broth uniformly turbid. 



Subculture of this proved pure culture of Staphylococcus aureus. 



b. After 15 minutes : both tubes free of growth. 



c. After 30 minutes : both tubes free of growth. 



From this it follows that izal 1 in 400 completely disinfects in 

 15 minutes; in 5 minutes already the number of living microbes 

 being greatly reduced (300 to 15). 



Experiment 3. — Pus of an acute submental abscess (mixed with 

 blood) was obtained ; 1 ccm. of the pus was diluted with 39 ccm. of 

 sterile distilled water (1 in 40). 



With 1 loop of this dilution made control agar culture. In 

 this about 12 dozen colonies came up; these were partly colonies of 

 streptococci, partly colonies of Staphylococcus aureus and alius. 



0'1 ccm. of izal was added to the diluted pus (1 in 400) ; after 

 well shaking it and keeping it for 5, 15, and 30 minutes, cultures 

 were made on agar and in broth, using for each tube 3 loops. 

 Incubated at 37° C. for 4 days. 



The result was this : — 



a. After 5 minutes : on agar 1 5 colonies of mixture of Staphylo- 

 coccus aureus and albus; no colonies of streptococci; broth slightly 

 turbid. 



Subculture of the broth showed mixture of Staphylococcus aureus 

 and albus, but the great majority were those of Staphylococcus 

 aureus ; no colonies of streptococci. 



b. After 1 5 minutes : both tubes were free of growth. 



c. After 30 minutes : both tubes were free of growth. 



From this experiment it follows that izal 1 in 400 disinfects 

 completely streptococcus in 5 minutes ; that it reduces living Staphylo- 

 coccus aureus and albus in 5 minutes to a considerable degree (from 

 432 to 15), and that it completely disinfects them in 15 minutes. 



The following table summarises the preceding results as regards 

 the capability or incapability of izal to disinfect the microbes of pus 

 of acute abscess : — 



