148 



BACTERIOLOGY 



stance gives a red coloration with nitrous acid, the theory 

 being that the cholera bacilli split off indol from the peptone 

 of the nutrient medium, and at the same time develop 

 nitrites which are decomposed by the addition of a strong 

 acid. Of all the other morphologically and biologically 

 similar micro-organisms, Vibrio Mctschnikqffi alone gives 

 this cholera reaction. 



According to Gruber and Schottelius, a still more trust- 

 worthy point of difference is the fact that the cholera bacilli 

 grow with particular luxuriance in a very dilute bouillon, and 

 develop a wrinkled membrane on the surface in a few hours, 



, A., ,- ,'- /icM&3&ftt ) ->:^V; 



tfrtN'* -i?iVi-- vfcVflfKSsJS^SiSs** 





FIG. 54. TYPHOID BACILLI FROM A PURE 

 CULTURE. (After Jaksch.) 



FIG. 55. TYPHOID BACILLI ('SPIDER- 

 CELLS'). Magnified 1,100 times. 

 (After Lbffler.) 



whereas the remaining micro-organisms show no such rapid 

 growth. But the most certain diagnostic of all assuredly 

 lies in the manner of growth on plover's egg albumen 

 characterised above. 



Brieger was able to obtain some alkaloids and toxalbu- 

 mins from cholera cultures, amongst others cadaverine, 

 putrescine, and choline. Pouchet also extracted toxines 

 from the actual cholera stools. 1 



Bacillus of typhoid fever. The bacilli of typlioid or en- 

 teric fever (the Typhus abdominalis of the Germans) are met 



1 [For an account of recent researches on cholera vaccination, see 

 Appendix] TK. 



