164 INTRODUCTION 



We have very frequently sought for the act of disappearance of the 

 granules in drops taken from the peritoneal fluid, but the number of these 

 transformed vibrios has never diminished, even after several days, and we 

 have therefore not been able to detect the phenomenon of dissolution of 

 the granules. In spite of all this, it is incontestible that the granular 

 transformation is a manifestation of a very grave change to which the 

 cholera vibrios have been subjected under the influence of the peritoneal 

 fluid of the immunized organism. 1 



Is this granular transformation, as MetchnikofT states, a mani- 

 festation of very grave lesions? The fact, established by him, 

 that one of these granules seeded on agar gives a colony of nor- 

 mal vibrios is not an index of a very profound alteration. Let 

 us consider for the moment that there can not be, in any sense, 

 a lysis of the cholera vibrios in the Pfeiffer reaction. One may 

 try by all sorts of methods to provoke the same phenomenon in 

 all kinds of animals with all kinds of bacteria, but without result. 

 It can only be secured with the cholera vibrios; they alone can be 

 transformed into granules. 



MetchnikofT, and later Bordet, showed that the reaction of 

 Pfeiffer could likewise take place in vitro. To obtain a granular 

 transformation it is only necessary to introduce the vibrios into 

 the fresh serum of an immunized animal. Bordet further 

 showed that this transformation was brought about by the in- 

 teraction of two principles, amboceptor and alexin. 



The amboceptor, thermostabile, is specific; that is to say, it is 

 only active toward the element against which the animal fur- 

 nishing the serum has been immunized. It exists only in traces, 

 or not at all, in the serum of normal animals. It develops as an 

 effect of immunization. 



The alexin, thermolabile, is, it appears, common. It exists in 

 as large an amount in a normal animal as in the immunized 

 animal. It is fixed by any element previously acted upon by a 

 specific amboceptor. 



Bordet next discovered that the blood of an animal prepared 

 by the injection of the red blood cells of a different animal species 

 formed specific amboceptor. If to a suspension of these cells 

 is added a heated serum of the treated animal (thus containing 



1 Metchnikoff. LHmmuniti dans les maladies infectieuses, Paris, 1901, 

 Masson et Cie. 



