x MODES OF DESTRUCTION OF B. PESTIS 295 



numbers, as will presently be described. In this con- 

 nection it will be necessary to bear in mind that three 

 platinum loops of the mixture (5 cc. of the disinfectant 

 and 5 drops of the emulsion of B. pestis) yielded in the 

 positive instances innumerable colonies of B. pestis in the 

 culture tubes. This disposes at once of an objection that 

 /uight possibly be raised, viz. that the amount of dis- 

 infectant carried over from the mixture to the culture 

 tubes might inhibit the subsequent growth of the microbe, 

 although the latter might still be alive. It also disposes 

 of a further criticism, viz. that the number of microbes 

 carried over by three platinum loops might not be large 

 enough. As just mentioned, in the fully positive in- 

 stances the whole culture surface was covered with crowds 

 of colonies. 



Series /.—March 25, 1904. 



A. — Watery solution of pure phenol . 1 in 200 



B. — Watery solution of pure phenol . . 1 in 100 

 C. — Watery solution of formalin (40 per cent) 1 in 100 

 D. — Watery solution of formalin (40 per cent) 1 in 50 

 Time of exposure of B. pestis, 5, 10, and 15 minutes. 



Cultures after exposure were made on sloped gelatine 

 (21° C), and inspected on April 5, with the following 

 result : — 



1. — Phenol 1 in 200, 5 minutes' exposure. Innumerable colonies — 



confluent mass. 



■*■'»' » n >> >> 



i" j> ii ii ii 



2. — Phenol 1 in 100, 5 minutes' exposure. Innumerable colonies. 



10 „ „ About 7 doz. colonies. 



15 „ 6 colonies. 



