YEASTS. 625 



is at first grayish-white, then yellowish. As seen 

 under the microscope, ray-like mycelium filaments are 

 developed, which divide into branches. The ends are 

 often swollen or club-shaped, and there are various 

 enlargements along the body of the filament. 



YEASTS (Saccharomyces). 



These micro-organisms are of the greatest importance 

 in brewing and baking, but as yet no important patho- 

 logical lesions in man have been attributed to them, 

 although certain recent experiments have shown that 

 some varieties when injected are capable of producing 

 tumors and many are pathogenic for mice. They are 

 are not uncommonly present in the air and in cultures 

 made from the throat. They consist of round or oval 

 cells, usually many times larger than the bacteria. 

 They usually reproduce themselves by budding, a por- 

 tion of the protoplasm budding, and finally being cut 

 off to form a new individual. 



40 



