YEASTS 195 



250 to 7oo mcn m l en gth and are about two-thirds as 

 wide as long. The characteristic feature of the yeasts 

 is their method of reproduction, which takes place by 

 a swelling out of a part of the cell wall like a ball, into 

 which the protoplasm flows; this is called ''budding." 

 When the daughter-cell arrives at the proper size, 

 the connection with the parent dissolves and the new 

 cell is free. Spores have been observed w r ithin the 

 yeast cells, and these develop into adult cells when the 

 old cell ruptures. Yeasts grow upon nearly any organic 

 substance providing there is moisture. The best media 

 and temperatures vary with the species. The kinds 

 pathogenic for man grow best upon foodstuffs con- 

 taining simple sugars, but may thrive also on complex 

 substances. They are grown with reasonable ease in 

 the laboratory, but care must be used to get them in 

 pure cultures as their development is slow. Their 

 peculiar effect upon carbohydrate-containing stuffs is 

 due to their enzyme which has the power of making 

 ethyl alcohol. How much effect this has upon the 

 production of disease in man is not known. 



Blastomycosis. The disease produced by yeasts in 

 man called Blastomycosis, and the causative agent is 

 called Saccharomyces Busse, after the man who first 

 described it. By the first, a genus name, it is seen to 

 belong to the same group as the principal beer-making 

 yeast, Saccharomyces cerevisice. It is not known just 

 how the disease is contracted, but the yeast probably 

 enters wounds, cracks, or hair follicles. It penetrates 

 into the deep layers of the skin and sets up abscesses 

 of slow development and spread. These may break 

 down and leave a sluggish ulcer which later shows a 



