222 Chapter VIII 



nomenon is produced. Under these conditions, a certain number of 

 the vibrios are at first united into masses, but a considerable number 

 remain isolated and motile. Some hours after inoculation the number 

 of clumps diminishes and the isolated vibrios become more numerous, 

 a fact which indicates a certain amount of adaptation of the vibrio 

 to the medium in which it now finds itself. But never, so long as the 

 vibrios remain free in the subcutaneous exudation, do they become 

 transformed into granules. 



Salimbeni 1 , in an investigation carried out in my laboratory, 

 endeavoured to satisfy himself whether or no Pfeiffer's phenomenon 

 is produced in the subcutaneous tissue of a horse that had been 

 hyperimmunised against the cholera vibrio. This animal had, during 

 a period of 1 4 months, received considerable quantities of these micro- 

 organisms, and the serum of its blood transformed the vibrios into 

 granules with great rapidity and intensity. In spite of such favour- 

 able conditions for the manifestation of Pfeiffer's phenomenon, it 

 was never produced beneath the skin of this horse. The vibrios 

 when injected in this position became completely motionless in a 

 [234] very short time, but they kept their vibrio form and remained alive 

 for a number of hours. The exudation drawn off up to 24 hours 

 after inoculation still gave growths of the cholera vibrio. 



As it is more easy to introduce, without effusion of blood, the 

 cholera vibrio into the anterior chamber of the eye than beneath 

 the skin, and as the aqueous humour contains no fixative, the absence 

 of the granular transformation in the first of these two situations has 

 been observed even by Pfeiffer himself. The demonstration of this 

 fact presents no difficulty, and for a considerable period we may 

 observe free and perfectly motile vibrios moving about in the aqueous 

 humour. The exudation from the eye contains many of these living 

 organisms, which when sown on culture media made their appearance 

 as colonies even when the fluid has been withdrawn from the eye 

 several days after inoculation. 



These carefully established facts show very clearly that the micro- 

 cytase is only met with in the fluids of the living animal in those 

 situations in which there are many pre-existing leucocytes and under 

 conditions in which the cells undergo a more or less marked phago- 

 lysis. This may be corroborated by a decisive experiment. When 

 we inject a suspension of the cholera vibrio directly into the veins of 

 a guinea-pig, well vaccinated against these organisms, and whose 

 de. I'Inst. Pasteur, Paris, 1898, t. xn, p. 199. 



