BACTERIA PATHOGENIC IN ANIMALS. 239 



are formed after a few days on plate cultivations; in 

 puncture cultures thin white granular threads develop ; 

 in stroke cultivations on gelatine a very tough grayish- 

 white coating is formed, which clings very closely to 

 the gelatine, and is not very bright, whereas the stroke 

 cultures on agar-agar are very bright in appearance. 



Their staining is not diflBcult, but they are very 

 easily decolourised, on which account Gram's method 

 cannot be employed. Aqueous solution of methylene 

 blue is Yery suitable for this purpose, and Loffler's 

 methylene blue is also to be recommended. A quite 

 unique peculiarity is to be perceived in stained pre- 

 parations ; the greater number of the individual cells 

 are not evenly stained ; only the two poles of the very 

 short rodlet are coloured, whilst a narrow space in the 

 middle remains unaffected. At first it looks as though 

 we were dealing with a diplococcus, but careful obser- 

 vation shows us that this is not the case, for the cell 

 membrane, even of the unstained portions, can be 

 clearly distinguished. 



A virulent epidemic occurring amongst wild animals, 

 called the game plague, is caused by a pathogenic 

 organism which is very similar to the bacillus of fowl 

 cholera ; in a similar manner bacilli are found in ferret 

 plague, rabbit septicsemia, duck cholera, swine 

 plague, pig typhoid, and hog cholera, which are 

 either quite similar to the chicken cholera bacillus, or 

 hardly to be distinguished from it. Some of these 



