180 MICRO-ORGANISMS AND FERMENTATION. 



form buds and spores. Amongst them are also found 

 irregular cells, and very large many-branched cells. 



It is also characteristic of this species that when kept in a 

 solution of saccharose the cells die within two years., whilst 

 most of the other Saccharomycetes examined can be pre- 

 served in this liquid for a much greater length of time. 



SACCHAROMYCES ACIDT LACTICI. GROTENFELT. 



Grotenfelt has described under this name a species of 

 Saccharomyces which, when added to sterilised milk, pro- 

 duces an intense curdling with formation of acid ; on gelatine 

 and agar-agar it forms white porcelain -like colonies, and on 

 potatoes it yields broad, moist, whitish-grey patches, which 

 soon become brown. In puncture cultivations in gelatine 

 short flask-shaped growths develop from the point of inocu- 

 lation into the gelatine. The cells are elliptical, 2*0 to 4*35 p 

 in length, and 1*50 2 -90 p- in breadth. 



When a solution of milk-sugar was inoculated, with the 

 addition of calcium carbonate, and the product distilled, 

 alcohol could be detected. In a neutral 3 per cent, solution 

 of milk-sugar, Saccharomyces acidi lactici yielded O'lOS per 

 cent, of acid in eight days. 



SACCHAROMYCES MINOR. ENGEL. 



The vegetative cells are completely spherical, in size up 

 to 6 /* in diameter, and are united in chains or in groups 

 composed of but few cells (6 to 9). Spore-forming cells 

 7 to 8 ^, and containing 2 to 4 spores of 3 ^ in diameter. 



This organism is, according to the above author, the most 

 active ferment in the fermentation of bread. 1 



1 Decisive experiments on the essential active factors in the fermen- 

 tation of bread have not yet been made. In the manufacture of white 

 bread, ordinarily " pressed-yeast " is used; this consists in the main of 

 alcoholic ferments, and according to the generally-accepted view the 

 yeast is the only active ferment. In the manufacture of black bread, 

 and in some countries also of white bread, so-called leaven is employed ; 



