DIFFERENCES BETWEEN ORGANISED AND UNORGANISED FERMENTS. 349 



that (apart from split-ferments such as Emulsin and Myrosin) the plastic matters are 

 transferred by the action of unorganised ferments from the passive into the active 

 condition. Fermentation by means of Fungi has, as Naegeli insists, just the opposite 

 character; its products are, without exception, less nutritious compounds, and it 

 destroys especially the most nutritious substances. 



' The contrast,' says Naegeli, ' appears most striking in the case of carbo-hydrates 

 and proteid substances. While the action of unorganised ferments produces from 

 them glucoses and peptones, fermentation by means of Fungi breaks up these com- 

 pounds into alcohol, mannite, lactic-acid, and into Leucin, Tyrosin, &c., — in some 

 cases several fermentations follow one another ; their products then become less 

 nutritious step by step. We may say, generally, that the Yeast-fungi render the 

 medium in which they occur chemically less suitable for nutrition by every process of 

 fermentation which they effect.' 



In fermentation by means of unorganised ferments the chemical transformation 

 proceeds smoothly and completely : dextrin is entirely transformed into grape-sugar, 

 cane-sugar entirely into inverted sugar, and albuminates entirely into peptones. In the 

 alcoholic fermentation, on the other hand, the products of which alone have hitherto 

 been quantitatively determined, only the greater part of the sugar is broken up into 

 alcohol and carbon dioxide, while, according to Pasteur, about 5% of the sugar is 

 decomposed by the way into glycerine, succinic acid, and carbon-dioxide. It is like- 

 wise certain that in the lactic acid fermentation, not all the sugar is decomposed 

 into lactic acid. Carbon dioxide especially appears to be a by-product of all fermen- 

 tations, due to the action of Fungi and of all putrefactive processes. 



The alleged difference between fermentation by means of unorganised ferments 

 and that due to the action of Fungi would be unintelligible if both processes were due 

 to the same cause. Every difficulty vanishes, on the other hand, if fermentation 

 by means of Fungi is caused, not by a contact substance (ferment), but by living pro- 

 toplasm. We then apprehend that while the ferment as a simple chemical compound 

 alters another chemical compound in a simple and equable manner so that all mole- 

 cules suffer the same kind of decomposition, an organised substance with its various 

 molecular movements and molecular forces produces more complicated decompo- 

 sitions. 



In this connection, Naegeli brings forward the fact that, as already remarked 

 above, the effects of proper ferment actions are also produced by acids, alkalies, and 

 even by water, especially at higher temperatures : the fact is quite otherwise with the 

 fermentations which are due exclusively to living Fungi, Naegeli puts his view of 

 fermentation due to organisms as opposed to that produced by unorganised ferments 

 in the following statement : — 



' Fermentation is therefore the transference of the movements of the mole- 

 cules, atomic groups, and atoms of various compounds composing living protoplasm 

 (which remain chemically unaltered in the process) to the fermentable material, by 

 which means the equilibrium between its molecules is destroyed, and it is broken up.' 



The older theory of fermentation, which classes it with the action of unorganised 

 ferments, has to assume that the various fermentations are effected by just as many 

 ferments in the Fungi producing them ; whereas Naegeli's theory seeks to explain the 

 difference between the fermentations as due to the different internal organisation of 



