U2 



OH NO. 



vibrio even if it sliould appeal- in rod or spherical form in the 0.3 per 

 cent alkaline peptone solution commonly used as an enriching media.* 

 I first determined for a number of strains of the cholera organism, the 

 reaction of the media in which the morphology of the vibrio was most 

 typical, and from these experiments found that for the cultivation of 

 cholera vibrios of typical morphology from suspected stools or other 

 materials, at least three solutions of peptone of the following reactions 

 should be used : 



1. 0.3 per cent acid 



2. 0.5 per cent alkaline 



3. 1.3 per. cent alkaline 



With phenolphthalein .is 

 an indicator. 



Pi'om Table 1 it may be seen that some cholera strains appear as rods 

 in 1 per cent acid peptone solution, and appear oval or spherical in form 

 in 1 per cent alkaline peptone solution. I have also isolated a strain 

 "Hoffman" (see Table 4) which even in a 0.5 per cent alkaline peptone 

 solution has the bacillary form, and changes to its typical curved form 

 only in a strong alkaline peptone of a reaction of 1.5 per cent. Strains 

 of this nature were occasionally isolated in the bacteriological examina- 

 tion of cholera stools during the recent epidemic. 



Table 1. — The change in morphology of cholera vibrios in peptone solutions of 

 different reactions {cultures incubated for twenty-four hours at 37° C). 



— = clear. 



± = a trace of turbiditv. 



+ = slight turbidity. 

 H- H- = moderate turbidity. 



+ -r - 



H- 4- + 



= marked turbidity. 

 = maximum turbiditr. 



No. 



Reaction of peptone 

 .solution. 



Strain "George." 



1 Acid, 1..T per cent 



Acid, 1.0 per cent . 

 Acid, O.b per cent . 



Neutral 



.■Alkaline, 0.5 per cent 



Alkaline. 1.0 per cent 



Alkaline, l.b per cent 



Alkaline, 2.0 per cent 



Alkaline, 2.5 per cent 



Turbidity. 



4 --I 



Morphology. 



Not visible in stained preparations. 



Several small .slender rods. 



The rods are .slightly curved and larger than in 



No. 2. 

 Moderately curved organisms, somewhat thick, 



both ends sharp. 

 Typical vibrios with some oval forms. 

 The vibrios are thicker and le.ss curved tlian in 

 No. .'). Some oval forms are present. 

 j Cocco-bacilli: here and there arranged like diplo- 

 I cocci. 

 Cocco-bacilli which are smaller than those in No. 7. 

 Not visible in stained preparations. 



^Kolle u. Wasserniann: Handbuch der pathogenen Mikroorganismen (1903) 

 3, 38. 



