700 | REPORT—1899. 
be supposed that glucose is resolved by fermentation into a mixture of glyceraldose 
and glyceroketose, which spontaneously interact forming a new hexose, 
HO.H,C CH,.0H 
eg 
C.0OH 
CH.OH 
CH.OH 
COH, 
-and that this in turn becomes fermented to isobutylearbinol, &c. It is not even 
known whether fusel oil is a product of fermentation by pureyeast; stillless, therefore, 
can it be decided whether the two successive fermentations here contemplated are 
the acts of one organism, or of organisms which are in any sense symbiotic. But 
it seems almost certain that one and the same organism can produce a variety of 
changes. 
11. Itis conceivable that two symbiotic, organisms may so act that the one pro- 
duces a substance A, the other a substance B, and that these products interact, 
forming a third substance; and that the two organisms attack either one and the 
same substance, or different substances. In such a case the fermentation would be 
different from that produced by either organism singly. Such would be a case of 
truest symbiosis. 
12. The conversion of lactic into butyric acid, of glycerol into butanol, and the 
formation of fat are certainly cases of fermentations in which synthetic changes 
eccur, and it may well be apart from enzymic action. 
13. There is little doubt that the importance of the part played by synthetic 
changes in fermentations, especially in the case of nitrogenous compounds, is at 
present far from being appreciated. 
14, But however many steps may be involved in some fermentations, at least 
the attack on several centres must be simultaneous, and must occur in one and the 
same circuit, as the change involves expenditure of energy at some centres, and this 
vaust be supplied from those others at which energy is developed. A complex 
carbohydrate molecule undergoing fermentation may, in fact, be compared with a 
series of voltaic cells of unequal electromotive force in series. It is difficult in 
any other way to account for the resolution of a single molecule into so many 
others, such as occurs, for example, in ordinary alcoholic fermentation. 
15. Such simultaneous attack is possible, probably because the enzyme is so con- 
stituted that it can attach itself at several points along the chain; the hydrolyte, 
in fact, is comparable with a complex lock, the hydrolyst with a complex key. 
It is possible thus to picture contact as being established between several more or 
less distant centres in a complex molecule, and a ‘ripple of change’ as pervading 
the system in consequence. Enzymes with restricted powers, such as invertase 
and diastase, probably can attach themselves only to a single centre, and their 
action is directly and simply hydrolytic. 
16. In some cases, such as the formation of fat, it would seem necessary to sup- 
pose that several molecules may become associated together through the agency of 
the hydrolyst, so that reductive processes may go on almost entirely in the one set ; 
whilst in another corresponding oxidative processes take place, which furnish the 
energy required to effect the reductions, On the other hand, it is conceivable that 
exygen directly intervenes in the formation of fat, and that the process is not 
merely one of hydrocatalysis. 
17. That no very complex mechanism is needed to produce effects such as are 
believed to be involved in fermentations follows from the fact that dextrose, for 
example, may be resolved into lactic acid by digestion with alkali and levulose 
into levulinic acid, CH,.CO.CH,.CH,.COOH, by heating it with an acid, the 
latter being an especially remarkable case. 
18. If the phenomena are as suggested, it does not seem probable that true 
symbiotic fermentation is likely to occur as a consequence of the simultaneous 
attack of a single molecule by several organisms; rather is it probable that 
associated molecules undergo change under the influence of a single organism or 
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