BACTERIA PATHOGENIC IN ANIMALS. 237 



laries of the internal organs. They occur, as a rule, 

 either singly or in pairs ; occasionally, however, they 

 are found in long threads, which are then often 

 matted ; they are motile, and grow as well at ordinary 

 room temperatures as at blood heat. On gelatine plate 

 cultivations, after a few days, peculiar bluish-grey 

 opalescent films are formed j these rarely appear on the 

 surface of the plate, but seem to prefer to spread 

 themselves out on the surface of the glass. These 

 films can be best distinguished if the plate is placed on 

 a piece of black paper. It can then be seen with a 

 magnifying glass that the film consists of innumerable 

 very delicate tangled thread-like strands, which are 

 almost transparent, and only to be distinguished from 

 the background in consequence of their opalescence. 

 These strands consist of bacterium threads which have 

 grown together. 



A similarly peculiar growth occurs in a puncture 

 cultivation ; in this case bluish-grey cloudy bundles 

 are formed, which stretch, out at right angles in all 

 directions from the line of ^inoculation, and which ap- 

 pear to be piled up one above the other, so that the 

 culture has been called the test-tube brush culture, 

 from its resemblance to the brush. Such a cultivation 

 cannot be confused with any other except that of the 

 Bacillus murisepticus . On agar-agar this swine 

 erysipelas bacillus develops very small, hardly visible 

 transparent droplets ; in bouillon thick heaps of bac- 



