82 VETERINARY BACTERIOLOGY 



CLASSIFICATION OF YEASTS 



Mycologists recognize a number of different genera in the group 

 of yeasts. It is probable that the yeasts do not constitute a 

 homogeneous group. The genus Saccharomyces includes such 

 forms as the common bread and brewer's yeast (Saccharomyces 

 cerevisice) which produce spores and are active in alcoholic fer- 

 mentation. The name Torula is sometimes given to similar yeasts 

 that are not spore producing. This latter name, however, is 

 incorrectly so applied, as it was previously and is now used to 

 indicate a genus of molds. The name Blastomyces has been 

 commonly accepted to indicate the yeasts pathogenic for man 

 and animals. It is probable that there is little reason for separation 

 of Saccharomyces and Blastomyces on the basis of their morphology, 

 but such a separation on the basis of pathogenesis seems to be 



advisable. 



CLASSIFICATION OF THE MOLDS 



Several hundred genera and many thousands of species have 

 been described. Of these, a few genera only contain species that 

 are pathogenic for man and animals. For a discussion of classi- 

 fication the student is referred to Chapter XXXVIII. 



