BACTERIOLYTIC REACTIONS 289 



grams) of an eighteen-hour-old culture of the suspected organism, 

 suspended in 1 c.c. of broth. A second animal (B) is given ten titer 

 doses ( = 2 milligrams) with the same quantity of organisms. A 

 third (C) receives 50 multiples of the titer dose, i. e., 10 milligrams, 

 of normal serum, however, but taken from an animal of the same 

 species as that furnishing the immune serum, together with the same 

 quantity of organisms as A and B, while a fourth guinea-pig ( D) is 

 injected with the same dose of bacteria, but without any serum. 

 The animals should all be of about the same weight (250 grams), 

 and are all injected intraperitoneally. To this end it is recommended 

 to make a small incision through the skin and to inject through a 

 cannula with a blunt point. By the aid of glass capillaries a droplet 

 of the peritoneal fluid is then procured through the same incision, 

 immediately after the injection, a second one twenty minutes later, 

 and a third one at the expiration of one hour. The specimens are 

 examined as hanging drops with an oil-immersion lens. If the 

 organism under consideration is the cholera vibrio, typical granule 

 formation and lysis will be observed in specimens A and B after 

 twenty minutes already, and at the latest at the expiration of one 

 hour; while in C and D there will be large numbers of actively motile 

 organisms or such at least in which the form has been well preserved, 

 the C animal being the control to A and B. The object of injecting 

 D is merely to prove that the organism in question is virulent and 

 this animal as well as C,> of course, should die, while A and B remain 

 alive. If the result then turns out as just indicated, the inference 

 is justifiable that the organism under examination was really the 

 cholera vibrio. 



2. Pfeiffer's Test as Applied to the Recognition of Recent Cholera 

 Infections. In this case the individual's serum is diluted with broth 

 in the proportion of 1 to 20, 1 to 100, and 1 to 500, when guinea-pigs 

 are each inoculated as described above with 1 c.c. of various dilutions, 

 together with one oese ( = 2 milligrams) of an eighteen-hour-old agar 

 culture of a virulent cholera strain. If extensive bacteriolysis can 

 then be demonstrated at the expiration of twenty minutes, or at most 

 an hour, the inference is justifiable that the person has recently 

 passed through an attack of cholera. 



PREPARATION OF THE CHOLERA IMMUNE SERUM. The cholera 

 immune serum which is required in test 1 (above) is prepared as 

 follows: A number of rabbits are each injected intraperitoneally 

 19 



