FERMENTS AND ARTIFICIAL FERMENTATIONS. 73 
smaller size, and which are now also placed in the 
class of Algz. 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 on ferments and fermentations, see 
Schutzenberger’s work on the subject. 
