ASCOMYCETES EUASCI YEAST 



249 



S ACCH ARO M YCETACEAE. 



Vegetative cells single or in small groups; mycelium usually not evident, 

 reproduction, by budding; ascospores, usually 4, produced in the cell; occasion- 

 ally 8, 3, 5, or seldom 1. 



The Saccharomycetes are fungi important in the process of fermenta- 

 tion. It is only in recent years that any parasitic species has been recog- 

 nized. Metchnikoff, in 1884, found a parasitic yeast Monospora bicuspidata in 

 Daphnids. Raum and Neumayer in 1891 declared yeasts were pathogenic. 

 Busse, 1894, demonstrated that certain yeasts were pathogenic. Tokishige 

 about the same time observed a yeast pathogenic for horses. Sanfelice isolated 

 from the cancerous-like growth of an ox a Saccharomyces which was pathogenic 

 for guinea pigs. The same author found another species in pigeons. Lydia 

 Rabinowitsch studied 50 species of yeasts, of which 7 proved to be pathogenic. 

 In 1895 Prof. Curtis found the second! case of Saccharomyces in a young man; 

 clinically the disease resembled a myxosarcoma. It is doubtful whether these 

 forms are true yeasts. Some of these appear to be Hyphomycetes rather than 

 Saccharomycetes. I have therefore discussed these under the form genus 

 Oidium. 



Fig. 76. Yeast. Saccfiaromyces mycoderma. A. Process of germination. B. Myceli- 

 um budding in a weak nutrient solution. C. (a) Yeast-like form budding; (b) long cells. 



