388 BACTEBIOLOGY. 



about one per cent, of alcohol, and some species are wholly- 

 unable to ferment sugar. A considerable number of species 

 have been described, and among these may be especially 

 mentioned several forms which are widely distributed in 

 the air. The so-called red-yeast is not one species but 

 rather a group name for a number of species or varieties. 

 Red and white torula are frequently deposited from the air 

 on gelatin plates. Occasionally a black yeast is met with. 



Until very recently the yeasts have been considered as 

 being wholly non-pathogenic. When introduced in large 

 quantity they may induce a catarrhal condition in the 

 stomach and in the intestines. When the' ordinary yeasts 

 are injected subcutaneously apparently no bad results fol- 

 low. Rabinowitsch, however, isolated seven varieties of 

 pathogenic yeasts. Monilia Candida, the cause of thrush 

 in children, is a yeast-like organism which is very patho- 

 genic for mice and rabbits. Mice were very susceptible; 

 rabbits less so, and guinea-pigs were refractory to the 

 several yeasts. Gram's method can be used to advant- 

 age for the detection of the yeast cells within the animal 

 body. 



Recently yeast-like forms have been described as oc- 

 curring in certain malignant new growths, such as sarcoma 

 and cancer. They are presumed to be identical with the 

 so-called inclusion cells. 



Moulds. 



\ 

 This group of organisms, known as thread fungi or 

 hyphomycetes, cannot be defined with the same degree of 

 precision as is the case with the bacteria and the yeasts. 

 It includes a large number of plants which differ greatly in 

 form, size, shape and color. As a rule the vegetative form 

 consists of threads or filaments which intertwine or inter- 



