FERMENTATION. I07 



n diameter. Film formation takes place most rapidly (seven to ten days) 

 t a temperature of from 20° to 22°, most slowly (two to three months) at 

 °to 7°C., and ceases altogether at 38° C. , andat5°C., at the other extreme, 

 ietween 20° and 30° C, the cells are frequently sausage-like and irregular ; 

 rom 6° to 15° C. the cells. are usually like the parent cells in younger 

 ultivations, but in older cultivations the forms are like those already 

 lescribed. 



This species, like all those investigated by Hansen, secretes 

 . peculiar substance, which, acting on saccharose or crude 

 ane sugar, inverts it to " invert " sugar ; the yeast then brings 

 .bout the fermentation of this latter substance, and also of 

 lextrose and maltose, giving rise to the formation of alcohol 

 .nd carbonic acid gas, with an evolution of heat and great 

 nultiplication of the yeast-cells. It does not seem to exert 

 .ny action on lactose or milk sugar. In this respect these 

 erments resemble mucor racemosus, which first brings about 

 he inversion of cane-sugar ; it also secretes invertase, which 

 lauses inversion of saccharose, the products of which it 

 erments ; it also sets up a weak fermentation in beer wort 

 if the maltose and dextrose present in that liquor. 



Reess' genus of Saccharomyces ellipsoideus Hansen divides 

 nto two — I. and II. 



2. Saccharomyces ellipsoideus I. is really a " wild " species 

 if wine ferment ; in beer wort it grows as a low yeast. It is 

 isually rounded or ellipsoidal in shape, though it sometimes 

 issumes the sausage form. The spores, of which two to four 

 .re usually found in a single ascus, are from 2 to 4^ in 

 liameter. 



These spores develop most rapidly (in twenty-one hours) at 25° C, most 

 lowly (eleven days) at 7.5° C, and are not formed at all at 32.S°C. at the 

 ne extreme, and at 4° C. at the other. Grown on the surface of beer wort 

 elatine, its colonies form a peculiar net-work along the line of the inocula- 

 ion streak. The surface membrane is fonned rapidly (eight to twelve 

 ays) at a temperature of from 33° to 34° C, most slowly (sixty to ninety 

 ays) at 6° to 7° C. ; it is always a delicate membrane, and cannot be grown 

 t 5° C. on the one hand and at 38° C. on the other. 



The most characteristic growth takes place at from 13° to 

 5° C, when it occurs as a complicated branching mass, 

 dth elongated cells, or threads, arranged in rows, with 

 everal lateral processes coming off at the points of junction, 

 lecondary branches are formed at the constrictions of the 

 •rimary branches. 



It appears to exert as powerful and rapid a fermenta- 



