434 MICRO-ORGANISMS AND DISEASE [cHAr. 



tity, as has been first shown by Van Ermengem ; ^ and 

 McLeod and Mills ^ found this toxin in a very effective and 

 concentrated form produced in the intestinal fluid of the 

 guinea-pig infected per os after Koch's method {see below). 



The effect of non-fatal doses of cholera vibrios (dead or 

 living) or of other microbes injected intraperitoneally into 

 the guinea-pig will be considered later on in connection 

 with artificial immunisation, at present suffice it to say 

 that the fijfa/ effect of cholera vibrios injected intraperi- 

 toneally into the guinea-pig proves nothing whatever as 

 to any specific action any more than is the case with 

 bacillus prodigiosus, and that the greater or lesser virulence 

 of one microbe as compared with another (as judged by 

 the relative amount injected intraperitoneally) proves 

 nothing whatever for or against intrinsic specific action. 

 I have shown ^ that by repeated intraperitoneal injection of 

 sterilised vibrios (of cholera, of Finkler) or of sterilised 

 bacilli (coli, prodigiosus, typhoid, proteus) taken from the 

 surface of recent Agar cultures and used in non-fatal doses, 

 the guinea-pigs become furnished with a high degree of re- 

 sistance against a subsequent intraperitoneal injection of 

 fatal doses of living vibrios or bacilli respectively. In the 

 case of the cholera vibrios, starting for the first injection 

 with a -J- steriHsed culture, and increasing the dose up to 

 i, then ^, -J, and finally i sterilised culture, allowing 

 eight to ten days to intervene between each two injections, 

 it will ultimately be found that such a prepared animal does 

 not react any further to the intraperitoneal injection of a 

 double or even treble otherwise fatal dose of living Agar 



^ Recherches stir h Microbe du ChoUra asiatiqiie, Bruxelles, 1885. 



^ Reports from the Laboratory of the Royal College of Physicians, 

 Ediidmrgh, vol. i. 



3 Centralbl.f. Bakt. nnd Parasit., 1893, and Report of the Medical 

 Officer of the Local Government Board for 1893. 



