The Character of the Flagella 345 



has not been found outside of the diseased animal body (or its immedi- 

 ate surroundings). \\.\i fatal to experimental animals when injected 

 beneath the skin in small numbers. In larger doses it will produce the 

 disease in swine. It ferments glucose with the formation of gas. It 

 does not coagulate the casein in milk. 



(b). Bacillus typhi abdominalis is slightly larger than the bacil- 

 lus of hog cholera and not so uniformly actively motile. It is found 

 in the intestines and organs of people suffering from typhoid fever and 

 is generally accepted to be its cause. Like the hog cholera bacillus, its 

 natural habitat outside of the diseased body is not known. It is not fa- 

 tal to experimental animals when they are inoculated with moderate 

 doses. It does not ferment glucose with the formation of gas* . It does 

 not coagulate the casein in milk. 



(c). The Bacillus coli communis is a very feeble or more actively 

 motile bacillus varying somewhat in size but usually about as large as 

 the typhoid bacillus. It is found in the healthy intestines of both man 

 and the lower animals. It does not appear to live in nature outside of 

 the animal body. It is/oi/a/ to rabbits when they are inoculated with 

 large doses of the pure culture. It ferments glucose with the forma- 

 tion of gas and coagulates the casein in tnilfi. 



Another very important feature in the study of the relation, 

 from a differential standpoint, that exists between the bio- 

 logical properties and the character of the flagella of these 

 bacteria, is the fact, which is verified by many observations, 

 that these organisms exist in nature (z. e., the coli in the 

 healthy intestines, and the hog cholera and typhoid bacteria in 

 the organs of the victims of their respective diseases), in vari- 

 ously modified forms in which the differences (biological and 

 pathogenic) which separate the more typical species are very 

 much diminished. This variation, especially in the patho- 

 genic properties of the typhoid and colon bacteria, has given 

 rise to a theory, advanced by Rodet and Roiix"', that the 

 typhoid germ is a modified form of the colon bacillus. In 

 the investigation of animal diseases, hog cholera and colon 

 bacteria have been found which varied in size and in their bi- 

 ological and pathogenic properties to a marked degree from 



*The fact that the typho'd bacilhis would not ferment glucose with the formation 

 of gas, was first pointed out by Dr. Theobald Smith in 1890. {Centralblatt f. Bakierio- 

 logie u. Parasitenkunde VII, 1890, p. 502). 



