378 ON THE LACTIC FERMENTATION 
The fact is certainly of extreme interest, because it seems to show that the 
breaking up of the sugar is not due to the mere presence of the growing organism 
in its vicinity ; otherwise the fermentation would be proportioned to the growth 
of the torula, and would therefore be more abundant in the shallow vessel. 
But the explanation of the difference of the results, as dependent on the necessity 
or otherwise of abstraction of oxygen from the sugar by the torula, seems to 
lack applicability without some addition to the hypothesis. For sugar does 
not lose any oxygen at all in being converted into alcohol and carbonic acid, 
and therefore the withdrawal of that element would be incompatible with the 
new arrangement of the atoms in a saccharine molecule. 
On the other hand, if we compare the formulae of glycerine and succinic 
acid with that of sugar, we see that the abstraction of an atom of oxygen from 
each of several atoms of grape-sugar might naturally lead to the simultaneous 
formation of the less complex atoms of the other substances out of the residual 
constituents of the sugar; the formation of the succinic acid involving the 
liberation of a certain amount of hydrogen, which again is required for the 
production of the glycerine: and further, that the relative proportions by 
weight in which the new compounds would be formed would be those in 
which they were actually found to present themselves by Pasteur in alcoholic 
fermentation." 
Thus the formation of the glycerine and succinic acid seems to be exactly 
explained by Pasteur’s theory of the deoxidizing agency of the torula upon 
sugar. But in order to account for the disruption at the same time of a very 
Pasteur quotes these first expressions of his theory, and adds that they ‘ n’ont rien perdu de leur rigueur ; 
bien au contraire, le temps les a consacrés ’ (op. cit., p. 257). When stating his present opinion he employs, 
it is true, terms which might seem capable of a different interpretation, viz.: ‘La fermentation par 
la levare s’est présentée 4 nous comme la conséquence directe d’un travail de nutrition, d’assimilation, 
de vie en un mot, effectuée sans gaz oxygéne libre. La chaleur consommeée par ce travail a da étre 
nécessairement empruntée de la matiére fermentescible, c’est-a-dire au corps sucré, qui, 4 la maniére 
des corps explosifs, dégage de la chaleur par sa décomposition.’ The latter of these sentences might 
seem to have no necessary reference to the question of abstraction of oxygen from sugar by the plant ; 
but it is immediately succeeded by the following: ‘La fermentation par la levire semble donc liée 
essentiellement a la propriété que posséde cette petite plante cellulaire de respirer, en quelque sorte, 
avec l’oxygéne combiné au sucre.’ Here the original theory is plainly restated, and we are led to infer 
that the decompositions of the sugar referred to in the former sentence as providing the necessary heat 
for the work of nutrition result from its deoxidation. 
* According to Miller’s Elements of Chemistry, the formulae of the three substances are—Glucose 
(i.e. grape-sugar), C,H,,O,; Glycerine, C,H,O,; Succinic acid, C,H,O,. Therefore, 5 atoms of glucose, 
less 5 of oxygen, are equal to 10 atoms of glycerine, less 10 of hydrogen ; and 2 atoms of glucose, less 
2 of oxygen, are equal to 3 of succinic acid, plus 10 of hydrogen. Therefore, 7 atoms of glucose, less 
7 of oxygen, leave the elements necessary for producing 10 atoms of glycerine and 3 of succinic acid. 
Now, the atomic weight of glycerine multiplied by 10 is 1860, and the atomic weight of succinic acid 
multiplied by 3 is 354, so that the weight of glycerine formed would be between five and six times the 
weight of succinic acid; and this is just about the proportion of the quantities of the two materials 
obtained by Pasteur from fermented sugar (see Miller’s Chemistry, vol. il, p. 161). 
