CYTOLYSINS 145 



Pfeiffer phenomenon. These discoveries were incident to the investi- 

 gation of immunity to cholera spirilla. The method is essentially that 

 of studying the changes taking place in the spirilla following intraperi- 

 toneal injection in guinea-pigs. If the guinea-pig had survived preceding 

 inoculations and had thereby developed immunity the injection of or- 

 ganisms was followed by loss of their motility, transformation into 

 oval translucent granules and finally disappearance of the bacteria with 

 complete recovery of the animal. If the spirilla were of only low 

 degree of virulence the same phenomenon could be observed in a 

 normal animal, but if the animal were highly immune it could survive 

 doses of virulent organisms much greater than those fatal for normal 

 guinea-pigs. It was found that the simultaneous intraperitoneal injec- 

 tion of serum from an immune pig and of spirilla into a normal pig 

 served to protect the animal and that this protection could be conferred 

 as well by heated as by non-heated immune serum. The mechanism in 

 all cases was the same and not dependent upon phagocytic activity. 

 Furthermore, the protection was found to be specific. Pfeiffer was 

 unable to demonstrate the phenomenon in vitro (hanging drop prepara- 

 tion) and therefore assumed that some substance provided by the peri- 

 toneal endothelium served to activate the bacteriolytic process. 



In the demonstration of the Pfeiffer phenomenon it is necessary to have 

 a series of fairly young guinea-pigs of about 200 grams in weight and a- culture 

 of cholera spirilla whose virulence is well established, because the virulence of 

 the organisms plays quite as important a part as their number. The immune 

 serum may be produced in the rabbit, goat or other animal by repeated inocula- 

 tion with the organisms. The organisms may be injected in measured volumes 

 of broth cultures or of saline suspensions of agar cultures ; they may also be 

 measured by weight by the use of a standard platinum loop which takes up 

 approximately 0.002 gm. organisms. The immune serum is diluted as indicated 

 in the following protocol and the bacteria and serum are injected simultaneously. 

 Peritoneal fluid is withdrawn at intervals of 10, 20, 30, 45, 60 minutes, the 

 intervals being altered as circumstances indicate. The withdrawal is by means 

 of drawn out capillary pipettes introduced into the belly cavity through a 

 small incision in the skin. The material may be examined in a hanging drop or 

 may be spread and stained by the ordinary bacterial dyes. A protocol from 

 Pf eiffer's own work follows : 



PFEIFFER PHENOMENON 



Weight of 0986 of Dose of 



guinea-pig spirilla immune Examination of 



in grams in grams serum in c.c. Result peritoneal fluid 



320 o 002 0.05 Lives After 15 minutes, only gran- 



ules present. 



240 0.002 0.02 Lives After 20 minutes, only gran- 



ules present. 



200 0.002 0.006 Lives Sterile after 35 minutes. 



220 0.002 0.003 Lives After 25 minutes, numerous 



granules, isolated, non- 

 motile spirilla. After I 

 hour practically sterile. 



220 0.002 o.ooi Died during After 25 and 50 minutes, 



night numerous granules but 



also numerous active spir- 

 illa. After loo minutes, 

 only active spirilla. 



10 



