210 A MANUAL OF BACTERIOLOGY 



prepared. If, on the other hand, the reaction be negative, 

 the organisms are unaffected after being in the peritoneal 

 cavity for an hour or so, and the organism is then con- 

 sidered to be a species different from that used for the 

 preparation of the immune serum. Thus, Pfeiffer's 

 reaction may be made use of to differentiate the cholera - 

 like vibrios from true cholera vibrios and the members of 

 the typhoid-colon group from another. 



The destruction of the bacteria by bacteriolysis is 

 regarded by some as being brought about by osmotic 

 changes, by others by processes analogous to digestion. 

 In the process of bacteriolysis the specific anti-bodies are 

 absorbed and used up, and for the lysis of a given quantity 

 of bacteria certain minimal amounts of both amboceptor 

 and complement are necessary, though the interaction is 

 not strictly quantitative. The same holds good for haemo- 

 lysis, and the facts relating to bacteriolysis and haemolysis 

 are almost interchangeable. 



Anti-endotoxic sera. -The comparative inefficiency of anti- 

 microbic sera, particularly typhoid, led Macfadyen to attempt to 

 prepare sera with microbial endotoxins, and the work was con- 

 tinued by Siidmersen and the writer. Horses were immunised 

 with the endotoxin obtained by the method described on p. 45, 

 and with a typhoid serum so prepared Goodall and the writer 

 obtained promising results. 1 



Method of applying Pfeiffer's reaction. For Pfeiffer's test, the 

 organism must be virulent, and a high-grade immune serum is 

 necessary. If the organism is not virulent, it is spontaneously 

 destroyed in the peritoneal cavity without the addition of immune 

 serum. The method may be best explained in the case of a 

 vibrio supposed to be the cholera vibrio. The cholera-immune 

 serum (obtained from a rabbit or horse repeatedly injected with 

 cholera culture) should possess a titre of not less than 0-0002 c.c., 

 i.e. this amount of serum mixed with one loop (2 mgrm.) of an 

 eighteen-hour agar cholera culture (virulent), suspended in 1 c.c. 



1 Proc. Roy. Soc. Med., vol. ii, 1907-8, Med. Sect., pp. 245 et seq. 



