BACILLI OF THE COLON-TYPHOID-DYSENTERY GROUP G59 



showing that the poison does not act upon the normal heart muscle 

 directly. 



Zinsser, Parker and Kuttner 55 have recently shown that in broth 

 cultures of the typhoid bacillus as young as five to six hours, a mildly 

 toxic substance is formed which can be recovered in filtrates, and which, 

 injected into rabbits intravenously, gives rise to definite symptoms, 

 after an incubation time of an hour or more. This substance is not 

 specific in that it is formed by many other different bacteria similarly 

 grown, and is not antigenic in all probability. It can also be obtained 

 by washing young agar growths repeatedly in salt solution, and filter- 

 ing. Whether or not this substance plays a part in the disease cannot 

 be stated at the present time. 



IMMUNITY AND ANTIBODIES 



Animals, may be actively immunized by the injection of typhoid 

 bacilli in gradually increasing doses. In actual practice, this is best 

 accomplished by beginning with an injection of about 1 c.c. of broth 

 culture heated for ten minutes at 60 in order to kill the bacilli. After 

 five or six days, a second injection of a larger dose of dead bacilli is 

 administered; at similar intervals, gradually increasing doses of dead 

 bacilli are given and finally considerable quantities of a living and fully 

 virulent culture may be injected without serious consequences to the 

 animal. While this method is convenient and usually successful, it 

 is also possible to obtain satisfactory immunization by beginning with 

 very small doses of living microorganisms, according to the early 

 method of Chantemesse and Widal, 56 and others. 



Such active immunization, successfully carried out upon rabbits and 

 guinea-pigs, within a short time after the discovery of the typhoid bacil- 

 lus, was believed to depend upon the development of antitoxic sub- 

 stances in immunized animals. This point of view, however, was not 

 long tenable, and was definitely disproven by the investigations of 

 Pfeiffer and Kolle 57 in 1896. These investigators, as well as a large 

 number of others working subsequently, have shown that there are 

 present in the blood serum of typhoid-immune animals and human 

 beings, bacteriolytic, bactericidal, and agglutinating substances, and 

 to a lesser extent, precipitating and opsonic bodies but no true anti- 

 toxins. 



55 Zinsser, Parker and Kuttner, Proc. of the Soc. Exper. Med. and Biol., Meeting, 

 Nov., 1920. 



56 Chantemesse and Widal, Ann. de Finst. Pasteur, 1892. 



57 Pfeiffer und Kolle, Zeit. f. Hyg., xxi, 1896. 



