224: Dynamic Theory. 



According to the opinion of others, " Yeast, like every living organ- 

 ism, shows phenomena of two kinds," assimilation and disassimilation. 

 The first is the appropriation of food in nutrition, and is necessarily 

 carried on simultaneously with the last, which is simply the rejection of 

 the surplus and the waste. The various constituents of the solution, 

 viz. , sugar, nitrogenous compounds and mineral salts, penetrate the 

 cases of the yeast cells by endosmose, undergo there suitable transform- 

 ations and are, in part, converted into tissues to form the new buds and 

 repair the old ones. The transformatory process converts the constit- 

 uent elements, which are not appropriated to the growth, repair and re- 

 production of cells, into alcohol and carbonic dioxide, neither of which 

 can be appropriated to the vital needs of the cells, and, consequently, 

 are eliminated. The above is, in effect, the view of M. Bechamp. 



As defined by Cornil and Babes, fermentations are ' ' chemical pro- 

 cesses undergone by substances broken up under the influence of organ- 

 isms without chlorophyl, which develop and live in the liquid which 

 ferments. " This last definition does not contradict the preceding one, 

 although it is noncommittal as to whether the constituents are broken 

 up inside the cells or broken up outside of them by the abstraction of 

 .such molecules as the cells require for their use; which abstraction 

 might be regarded as depriving the constituents of a bond necessary to 

 their union a sort of keystone which, being pulled out, allows the 

 structure to fall into pieces, which thereupon employ their liberty in 

 the formation of the new compounds, alcohol and carbonic dioxide. 



Schiitzenberger's view is practically the same as that of Cornil and 

 Babes. It may therefore be concluded that the general opinion is that 

 yeast and other organic ferments are fungi of the simplest kind. Each 

 cell constitutes an independent individual competent to put forth new 

 cells by budding, or end its own existence in the production of two to 

 four reproductive spores. Some years ago yeast was classed as a Tor- 

 ula, but as Torulse never have spores that classification is abandoned, 

 and yeast is placed in a family of its own, Saccharomyces. The cells of 

 yeast and of fungi generally are, in many respects, similar in function 

 and anatomical equivalence to those cells in plants which do not possess 

 chlorophyl. All such cells, as we have seen, are, of necessity, para- 

 sitic and dependent, directly or indirectly, on the chlorophyl cells. 

 These latter secure the carbon from the atmosphere and pass it into the 

 parasitic cellular tissues of the plant in the shape of an insoluble starchy 

 substance, or as saccharose. These substances are unassimilable in the 

 tissues of the plants until they undergo alteration the same process 

 that is practiced on the saccharine elements in yeast fermentation as the 

 first step in that fermentation. This alteration thus forms glucosides, 

 that are assimilable. It is because of this unassimilability that these' 



