420 BACTERIOLOGY. 



effects of its introduction into animals were manifestly 

 of toxic l origin, while others regarded them as evidences 

 of genuine infection. 2 These diversities of opinion are 

 hardly surprising when we remember that animals 

 never suffer naturally from typhoid fever, and therefore 

 offer many obstacles to its faithful reproduction, and 

 that the vigor of this organism when cultivated from 

 various sources is liable to a wide range of fluctuation. 

 Numerous investigations lead to the belief that the 

 poison peculiar to this organism is so intimately bound 

 up with its protoplasmic structure as to make its sep- 

 aration difficult, if not impossible. However, by the 

 use of dead cultures (i. e., cultures of well developed 

 organisms destroyed by heat) results are obtained 

 that leave no doubt that the clinical symptoms and 

 pathological changes seen in man and in animals under 

 experiment are referable to a specific intoxication, and, 

 as a rule, the only effects that follow the introduction 

 of this organism into animals are referable to the in- 

 toxicating action of the materials used. In fact, the 

 results of modern investigations have placed bacillus 

 typhosus in the category of endotoxin producers, and 

 through the use of tha toxins (not pure, but mixed with 

 other substances in the culture media) produced by it 

 animals have been rendered immune from otherwise 

 fatal doses of highly toxic cultures. The serum of such 

 animals has also been shown to possess a certain degree 

 of immunizing power. 3 



1 Toxic poisonous results not necessarily accompanied by the 

 growth of organisms throughout the tissues. 



2 Infective or septic poisoning of the tissues as a result of the 

 growth of bacteria within them. 



spfeiffer and Kolle: Zeitschrift fur Hygiene und Infektionskrank- 

 heiten, 1896, Bd. xxi. S. 208. 



