STUDIES IN IMMUNITY. 



I. THE ADAPTIVE CHANGES OF BACTERIAL CULTURES 

 IN THE BODY OF IMMUNIZED ANIMALS* 



By JULES BORDET, STUDENT OF MEDICINE. 



Bacteria are highly adaptable. They frequently change both 

 morphologically and functionally. Their virulence is also an essen- 

 tially fluctuating property, that increases or diminishes according 

 to the conditions to which the pathogenic organism is subjected. 



The vibrio Metchnikovi, as described by Gamaleia, is very virulent 

 for certain animals. A small amount of culture suffices to kill 

 guinea-pigs. Sterilized bouillon in which the organism has been 

 grown is also very toxic for these animals and kills in a mean dose 

 of 2 c.c. to 100 grams of body weight. 



Guinea-pigs, although they succumb to this micro-organism so 

 easily, become immunized when they have received one or two 

 injections of sufficient quantities 0.5 to 1 c.c. per 100 grams) of a 

 culture freed from living bacteria by filtration or by autoclaving. 

 The protection obtained in this manner is constant. 



Metchnikoff has shown us, however, that, when a guinea-pig pro- 

 tected in this manner is given a small amount of a virulent culture 

 of living organisms, the latter are not immediately destroyed. 

 They disappear only after a relatively long period, 60 to 90 hours 

 if injected subcutaneously, or 6 to 7 days when injected into the 

 anterior chamber of the eye. There is, however, a much more 

 notable collection of leucocytes at the point of inoculation than in 

 an animal that has not been protected against the disease. Not 

 only do the vibrios remain alive, but they lose none of their harmful 



* Adaptation des virus aux organismes vaccinas. Annales de lTnstitut Pas- 

 teur, VI, 1892, 28. From the laboratory of Prof. Errera. Botanical Institute, 

 Brussels. 



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