III. STUDIES ON THE SERUM OF VACCINATED 



ANIMALS* 



By DR. JULES BORDET. 



Pfeiffer's Phenomenon (The Extracellular Granular 

 Transformation of Vibrios). 



I. Interpretations given to Pfeiffer's Phenomenon. 



Pfeiffcr f found that if a certain amount of cholera vibrios sus- 

 pended in bouillon is injected into the peritoneal cavity of a rabbit or 

 guinea-pig well immunized against cholera, that a certain number of 

 these organisms undergo within a short time an interesting change. 

 They lose their motility and then contract into globules which at 

 first are oval and then rounded. These globules resemble cocci. 

 They subsequently become easily stained and according to Pfeiffer 

 they finally break up, and in this way the culture introduced is 

 rapidly destroyed. 



The most important part of Pfeiffer's discovery lies in the fact 

 that this retrograde transformation of the vibrio takes place for the 

 most part outside the cells. As may easily be imagined Pfeiffer has 

 drawn from these observations conclusions which would seem un- 

 favorable to the phagocytic theory. This eminent bacteriologist 

 has still further noted that the same phenomenon occurs if the 

 vibrio is given to a normal animal, provided a small amount of 

 preventive serum is injected simultaneously. The dose of this 

 serum varies naturally with its activity, but if very strong the dose 

 is very small. The serum causes the same phenomenon when 

 deprived of all bactericidal property by heating to GO degrees or 70 

 degrees. According to Pfeiffer the phenomena cannot occur with- 

 out the cooperation of the living animal. According to this author 



* See p. 8. 



t Pfeiffer, Zeit. fur Hygiene XVIII, 1S94, 1. 

 56 



