250 THE BLASTOMYCETES 



Microscopical Appearances. Long cells, which do not transmit 

 light so strongly as the saccharomycetes. 



Biological Characters. On wort gelatine, small dim light grey 

 spots, which either spread over the surface or cause a shell-shaped cavity 

 in the medium. 



On Wort a greyish-white, thickly matted film develops, the optimum 

 temperature being 15 C. 



Actions. It causes only a weak alcoholic fermentation, no acetic acid 

 fermentation, but exerts a deleterious action on fermented fluids by 

 producing abnormal chemical changes. 



THE TORUL.E. 



These yeasts are widely distributed in nature, and occur in round or 

 elongated forms and develop no spores. Reproduction takes place by 

 budding, and often at the same time a mycelium is formed. Gelatine 

 media are not liquefied. The various forms are distinguished by the 

 colour of the pigment produced. 



1. White, Hefe. 



2. Rose, 



3. Black, 



They cause only a very weak alcoholic fermentation. There are, 

 however, some species that grow with distinct fermentation properties. 



PATHOGENIC BLASTOMYCETES. 

 SACCHAROMYCES HOMINIS. 



Found in an infectious disease, which began with a subperiosteal 

 inflammation of the tibia, terminating in a chronic pyaemia. 



Microscopical Appearances. Round or oval cells, double con- 

 toured, and possessing capsules. 



Biological Characters. On Gelatine Plates, prominent, round, 

 non-liquefying colonies. 



On Agar, a white coating. 



On Potatoes, a greyish-brown coating. 



On Blood Serum, a dim drop-like coating. 



Bouillon is clouded, a film growing on the surface. 



In Grape Sugar Bouillon fermentation takes place, alcohol and CO 2 

 being formed. 



Pathogenesis. In rabbits a local abscess forms. Mice die from 

 septic changes. 



