154 ESSENTIALS OF BACTERIOLOGY 



and cholera-vaccinated individuals contains the same bac- 

 tericidal substances. 



Allied Varieties. Many vibrios resembling the spirillum of 

 cholera have been isolated from drinking-waters and from 

 the stools of persons suffering with diarrhea, and some bac- 

 teriologists are inclined to consider them as varieties of the 

 true cholera spirillum, which under certain conditions become 

 pathogenic. Among these are Spirillum berolinense, S. dun- 

 barii, S. danubicum, S. of Wernicke, S. bonhoffii, S. weibeli, S. 

 schuylkilliensis, S. milleri, S. aquatilis. The last two are 

 non-pathogenic for experiment animals, also the Finkler- 

 Prior vibrio, vibrio Metchnikovii, and tyrogenum, which have 

 historic interest because of their close identity with the 

 cholera organism, but with the agglutination tests and 

 Pfeiffer phenomenon they have been shown to be dissimilar. 



Conclusions of International Committee of Public Hygiene, 

 Adopted October p, 1911. Every choleriform vibrio can be 

 considered as truly choleraic which presents agglutination in 

 the proportion of at least 1:1000 by a cholera serum of 

 1:4000 activity, or a positive Pfeiffer reaction, and every 

 choleriform affection in which is encountered such a vibrio 

 should be considered as a case of cholera. 



Method of Pfeiffer. i. Secure immune serum by injecting 

 into peritoneal cavity of a rabbit an entire agar culture which 

 has been killed by heating for one hour at 56 C. Four- 

 teen days after collect the blood-serum. 



2. Dilute the suspected vibrio by adding one loopful of an 

 eighteen-hour-old agar culture to i c.c. meat water. 



3. Add to the above about i milligram of immune serum 

 and inject this into peritoneal cavity of a guinea-pig. 



4. At the same time a second guinea-pig is inoculated with 

 diluted culture (2), but without the serum. 



5. A third guinea-pig is inoculated with a similar dilution 

 of culture to which has been added about 10 milligrams 

 normal rabbit serum. 



6. At the end of twenty minutes, and again at the end of 

 one hour, some of the peritoneal fluid is examined from each 



