THE BIOLOGICAL CHARACTERS, ETC. 29 



observations made upon excreta would certainly be more 

 practicable. With the object of establishing- a sound differ- 

 ential diagnosis between bacillus typhosus and other micro- 

 organisms which are possibly closely allied, a considerable 

 amount of work has been performed, some of which will 

 here be briefly mentioned. 



Purely morphological considerations are certainly insuf- 

 ficient to differentiate bacillus typhosus from many other 

 microbes. This bacillus is met with in the tissues in the 

 form of a short, relatively thick rod with rounded ends, 

 which when cultivated frequently grows into threads with a 

 much smaller diameter. Escherich's bacterium and its 

 numerous varieties, the numberless typhoid-like bacilli 

 isolated from water and the bacillus levans recently de- 

 scribed by Lehmann (9) may all as far as shape is concerned 

 be mistaken for the typical virulent specific microbe when 

 isolated from the spleen of a typhoid patient. According to 

 Luksch (10) bacillus typhosus exhibits much more lively 

 movements than the bacterium coli, and micro-photographs 

 show that the former of these is provided with 8-12 cilia, 

 which are attached both to the sides and ends of the bacillus, 

 while the latter only possess 1-3. Neither stains with Gram's 

 method and no spore formation takes place. Shortly after 

 the discovery of the bacillus typhosus a sporing stage was 

 described by Gaffky, but this observation has not been 

 confirmed. Recently Almquist (11) considers that spore 

 formation can take place both in E berth's and Escherich's 

 bacteria. His method for demonstrating this consists in 

 filling Erlenmeyer's or Pasteur's flasks with damp filter-sand 

 or sand soaked with manure. This medium is sterilised and 

 then inoculated with a bouillon culture of the microbe. The 

 flasks are then placed for at least a month in an ice chest. 

 By this time all the vegetative forms have disappeared and 

 minute bodies about '$/n are found in the culture medium. 

 He regards these bodies as spores, and describes them, when 

 examined in a hanging drop of bouillon, as growing into rods 

 which again break up into spores. How far these bodies 

 deserve this name is doubtful, and Ilkewicz (12), who by a 

 modification of Kolossow's method has succeeded in staining 



