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TRANSACTIONS OF SECTION B. 699 
tion du sucre dans le moat est suffisante pour contrarier leurs sécrétions 
diastasiques. 
La symbiose des mucédinéés saccharifiantes et des levures permet d’effectuer 
industriellement la fermentation directe de l’amidon des grains ou des pommes de 
terre et de supprimer 4 peu prés totalement l’emploi du malt ou des acides pour la 
saccharification en distillerie. 
Ce principe de la symbiose s’é6tendra probablement dans l’avenir a la fabrica- 
tion de beaucoup d'autres substances que l'industrie prépare aujourd’hui pour ses 
besoins, 
Symbiotic Fermentation : its Chemical Aspects. 
By Professor H. E. Armstrone, /.2.S. 
1. It is open to question whether the establishment of symbiotic relationships 
inyolves more than a subdivision of labour—whether the associated organisms 
combine in carrying the chemical change through any one phase. 
2. There is an absence of positive evidence tending to show that the one member 
of a pair of symbiotic organisms or agents does more than prepare the way for the 
other by effecting a change which the second is incapable of inducing, leaving it to 
the second to carry on changes in which the initiating organism plays no part. A 
rough parallel to the case here contemplated would be that afforded by the 
occurrence of lactic followed by butyric fermentation under the influence of 
distinct organisms. These are strictly independent and sequent phenomena, the 
one change apparently setting in only when the other is complete. 
3. In symbiotic fermentation, however, the two sets of changes seem at least to 
run parallel. 
4, It may be a function of the one organism to remove from the sphere of 
action, as it arises, a product which would tend either to inhibit the change by 
which it is formed or to promote its reversal. 
5. Or the one organism may produce a change which, although minute, is 
sufficient to place the companion organism under the most favourable conditions. 
For example, a minute proportion of acid favours the hydrolysis of cane sugar by 
invertase. Hence it may be supposed that in a neutral or faintly alkaline solution 
yeast would ferment sugar only slowly, if at all, whilst if associated with an 
organism capable of producing, say, a minute proportion of lactic acid, it would act 
rapidly. A case apparently of symbiosis, which possibly comes within this 
definition, is that referred to by Marshall Ward as studied by Van Senus. 
6. Or, again, the one organism may become associated with the hydrolyte, and 
thus shield or mask a particular ‘centre’ in it, thereby making it possible for the 
second organism to actively affect the molecules at other centres. This case 
corresponds to the removal of a ward from a lock, and.the consequent possibility 
of using a simpler key. What is in some cases a more nearly exact parallel is 
afforded by the production of glycuronic acid by the oxidation of the compound of 
glucose with chloral: in glucose, the COH centre is super-attractive to most 
oxidising agents, but when this centre is masked the attack is transferred to the 
opposite CH,(OH) group. 
7. Another case is considered subsequently (§ ii.). 
8. Fermentation is certainly at bottom a process of hydrocatalysis, and it can 
scarcely be doubted that the function of the enzyme is to introduce water into the 
circuit of change—in fact, to establish a circuit in which hydrolytic changes can 
occur, although not of the ordinary kind, but reductive on the cne hand and oxida- 
tive on the other. 
9. Hence we may speak of the substance fermented as the hydrolyte, of the 
ferment as the hydrolyst, and of the products of hydrolysis as the hydroschists. 
10. It is more than probable that the products ordinarily obtained are but end 
products of a series of changes, and that only some of these are enzymic, whilst 
others occur, as it were, naturally, and are partly analytic and partly synthetic in 
character. Thus, in the formation of the inactive amyl alcohol in fusel oil, it may 
