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 
