442 THE BACILLUS OF TYPHOID FEVER. 



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 (Pfuht). 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 17 !N"0 3 ). 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. 



Numerous experiments have been made to determine the amounts 

 of various germicidal agents required to destroy the vitality of this 

 bacillus, and the action of antiseptics in restraining its development. 

 For the results of these experiments the reader is referred to the 

 sections in Part Second relating to the action of antiseptics and disin- 

 fectants. 



Pathogenesis. The very numerous experiments which have been 

 made on the lower animals have not been successful in producing in 

 any one of them a typical typhoid process. Nor is this surprising, 

 in view of the fact that, so far as is known, no one of them is liable to 

 contract the disease, as man does, by the use of infected food or 

 water. 



The experiments of Frankel and Simmonds show that when con- 

 siderable quantities of a pure culture of this bacillus are injected into 

 the circulation of rabbits through the ear vein, or into the peritoneal 

 cavity of mice, a certain proportion of the inoculated animals die, 



