THE BACILLUS OF TYPHOID FEVER. 363 



available, there is nothing improbable in the supposition that they are 

 simply varieties, and that, as the result of a saprophytic mode of 

 life, this bacillus may undergo more or less permanent modifications. 



In the writer's experiments (1887) the thermal death-point of the 

 typhoid bacillus was found to be 56 C., the time of exposure being 

 ten minutes ; and potato cultures containing the refractive granules 

 described by Gaffky as spores were found to be infallibly destroyed 

 by a temperature of 60 C. This result has been confirmed by Buch- 

 ner (1888) and by Janowsky (1890), and the inference seems justified 

 that these granules are not reproductive bodies, as was at first be- 

 lieved ; for spores are distinguished by their great resistance to heat 

 and other destructive agencies. According to Buchner, the bacilli 

 containing these refractive granules are even less resistant than fresh 

 cultures in which they are not present, and he is disposed to look 

 upon them as representing a degeneration of the protoplasm of the 

 cells. They do not stain by the methods which are successful in 

 staining the spores of other bacilli, and, in short, present none of the 

 characters which distinguish spores, except the form and high re- 

 fractive power. 



The typhoid bacillus retains its vitality for many months in cul- 

 tures; the writer has preserved bouillon cultures for more than a year 

 in hermetically sealed tubes, and has found that development 

 promptly occurred in nutrient gelatin inoculated from these. Dried 

 upon a cover glass, it may grow in a suitable medium after having 

 been preserved for eight to ten weeks (Pfuhl). When added to 

 sterilized distilled water it may retain its vitality for more than four 

 weeks (Bolton), (forty days Cassedebat), and in sterilized sea- water 

 for ten days (De Giaxa). Added to putrefying faeces it may preserve 

 its vitality for several months (Ufflemann), in typhoid stools for three 

 months (Karlinski), and in earth upon which bouillon cultures had 

 been poured for five and one-half months (Grancher and Deschamps). 



In hanging-drop cultures this bacillus may be seen to exhibit very 

 active movements, the shorter rods rapidly crossing the field with a 

 darting or to-and-fro, progressive motion, while longer filaments 

 move in a serpentine manner. 



In addition to the volatile fat acids which, according to Brieger, 

 are formed in small amounts in cultures of the typhoid bacillus, and 

 to lactic acid formed in solutions containing grape sugar, a basic 

 substance possessing toxic properties has been isolated by the chemist 

 named his typhotoxine (C,H l7 N"O a ). Brieger supposes that other 

 basic substances are likewise formed, but believes this to be the speci- 

 fic product to which the pathogenic action of the bacillus is due. It 

 is a strongly alkaline base, which produces in mice and guinea-pigs 

 salivation, paralysis, dilated pupils, diarrhoea, and death. 



