xxij PATHOGENIC ORGANISMS 581 



show (Journal of Path, and Bad., November, 1894) that 

 only a local immunity against the streptococcus of erysipelas 

 or its toxin is produced in the rabbit in one ear previously 

 ihe seat of erysipelas, and further that also in the process of 

 immunisation of horses against diphtheria the region of a 

 former inoculation acquires resistance against the new dose, 

 whereas a new region of the skin is more suitable for the 

 purpose (Cobbett, Journal of Path, and Bait., January, 

 1896). 



Again, the peritoneum of a guinea-pig may be immunised 

 against the living or dead cholera vibrio by repeated pre- 

 vious intraperitoneal injections of cholera vibrios, without 

 its alimentary canal being immunised against the growth and 

 muUiplication of the cholera vibrio (R. Pfeiffer and Wasser- 

 mann, Klein). Koch and Gaffky showed that sheep 

 successfully vaccinated after Pasteur's method of subcuta- 

 neous protective inoculation are still subject to anthrax by 

 ingestion of spores. 



R. Pfeiffer in a series of publications (already referred to 

 in the chapter on Cholera) has demonstrated that by re- 

 peated intraperitoneal injections of guinea-pigs with living 

 cholera vibrios, at first in small non-fatal, then gradually 

 rising doses, the blood and blood-serum of the animal, as the 

 immunity becomes greater and greater, possesses higher and 

 higher germicidal or immunisitig potency against cholera 

 vibrio : the higher the degree of immunisation the greater 

 the germicidal power of the blood-serum. When a definite 

 quantity of this " cholera serum " is mixed with a definite 

 otherwise frftal quantity of living cholera vibrios and injected 

 into an unprepared animal no result follows, the animal 

 survives and remains well ; already after a short time, in 

 twenty minutes or so, after injection the vibrios degenerate 



