FERMENTS AND ARTIFICIAL FERMENTATIONS. 73 



smaller size, and which are now also placed in the 

 class of Algae. We shall return to this subject when 

 we come to speak of bacteria. 



The structure of ferments is very simple : each 

 plant is generally composed of a single cell, spherical, 

 elliptical, or cylindrical, formed of a thin cell- wall, con- 

 taining a granular substance called protoplasm, which 

 is the essential part of the plant. These cells have an 

 average diameter of ten micro-millimetres. They 

 grow and bud, and when one of them reaches a certain 

 size, a median constriction occurs ; it divides into two 

 parts, resembling the mother cell, and these some- 

 times separate, sometimes remain united in a group 

 or chaplet (Fig. 35). This mode of multiplication 

 continues as long as the plant remains in a liquid 

 favourable to its nutrition. But if its development is 

 hindered, if, for example, the liquid dries up, the pro- 

 toplasm contained in each cell contracts, and is 

 transformed into one or more globules, which are 

 the spores or endogenous reproductive organs of the 

 plant. These spores may remain undeveloped for 

 a long while, may become perfectly dry, and may 

 even be subjected to a very high temperature, without 

 losing the power of germination when they are again 

 placed in conditions favourable to their development. 

 They then reproduce the plant from which they had 

 their birth, and are multiplied in the same manner.* 



* For further details ou ferments and fermentations, see 

 Schutzeuberger's work on the subject. 



