BACILLUS TYPHI ABDOMINALIS. 251 







the surface in the neighbourhood of the track of in- 

 oculation has acquired a somewhat moist, more shiny 

 appearance. If this part of the potato is touched with 

 a platinum wire it gives the impression as if the surface 

 was covered with a resistant skin ; and if we examine 

 microscopically a minute portion from the surface we can 

 easily see that this skin consists of masses of bacilli 

 which have taken possession of the soil over a great 

 extent, often over the whole surface. If the inocu- 

 lated potato is kept at 85 C. the development of the 

 layer of bacilli occurs more rapidly, while otherwise 

 the appearance of the potato remains the same. 



In all these cultivations the bacilli appear under the Morphological 

 microscope as short, thin rods similar to those observed thTcuitlted 

 in the tissue. Nevertheless long pseudo-threads are bacilli. 

 almost always formed in the cultivations, and there are 

 also marked differences in length corresponding to the 

 various stages of growth. It is also possible to stain 

 culture preparations with aniline dyes, but it is more 

 difficult than the stainiDg of other bacilli (e.g., Bacillus 

 anthracis). Further, the bacilli taken from the culti- 

 vations show distinct and often fairly active move- 

 ments. Spore formation can not be 

 observed in cultivations kept at 15 

 18 C. ; at 20 C. a few spores are 

 formed, and between 80 and 42 C. 

 the spore formation is plentiful. The 

 spores are situated at the end of the cultivation x 

 rods, and only one spore is formed showing on the 



in each rod in the form of a highly 



refracting round body, occupying the and free spores. 

 whole breadth of the bacillus. Where two bacilli are 

 joined together it is always the two ends not in contact 

 which bear the spores. 



Inoculation experiments on animals have as yet been Experiments 

 without result, whether the material used was typhoid on ammals - 

 stools or the pure cultivated bacilli. Those few experi- 

 ments in which a typhoid disease was said to follow 

 inoculation or feeding have evidently been made with 

 impure material containing other active bacteria. It is 



