214 



PATHOGENIC BACTERIA. 



appearance when the central part is pale and the periphery 

 red. As the colony ages the red color is lost and it be- 

 comes dull white. The colonies are very adherent to the 

 surface of the medium, and are said to be of cartilaginous 

 consistence. The organism also grows in milk without 

 coagulation. 



Upon potato the development is meagre, slow, and 

 with very little tendency to chromogenesis. The color- 

 production is more marked if the potato be acid in reac- 



FIG. 62. Streptothrix Madurae in a section of diseased tissue (Vincent). 



tion. Some of the colonies upon agar-agar and potato 

 have a powdery surface, no doubt from the occurrence of 

 spores. It is, of course, an aerobic organism. 



Under the microscope the organism is found by Vin- 

 cent to be a streptothrix a true branched fungus con- 

 sisting of long bacillary branching threads in a tangled 

 mass. In many of the threads spores could be made out. 



