99 
as the oxidation of salicylic aldehyde under the influence of aldehy- 
dase partake of the nature of anaerobic fermentations, and, as is well 
known, the oxygen required for the latter processes is furnished by 
various oxygen-containing substances participating in the fermenta- 
tion. In this connection it is interesting to recall that Traube pro- 
vided for such cases in his general theory of fermentation. According 
to this distinguished observer the oxygen of water might under cer- 
tain conditions be transferred to the oxidizable substance by means 
of a ferment, and in the fermentation of a compound like sugar the 
oxygen present in one part of the molecule might be transferred to 
another part of the molecule, thereby giving rise, after splitting, to 
one substance richer in oxygen than the original, and to another 
poorer in this element. Such a change is met with in the breaking 
up of glucose into carbon dioxide and alcohol by yeast. It is inter- 
esting to note in this connection that similar changes have been met 
with among inorganic substances; thus, when an aqueous solution 
of phosphorous acid is heated, phosphoric acid and phosphine are 
produced — 
4 H 3 PO 3 = 3H 3 P0 4 + PH 3 
Whether water actually participates in such changes is at present 
unknown. In my opinion these simple processes would warrant 
further investigation from the point of view of anaerobic fermentation. 
In this connection Abelous and Gerard ( 5,1 °) have shown that 
extracts of various animal tissues have the power of reducing nitrates 
to nitrites. So also it was afterwards found by Abelous ( 3 ) that the 
juice of the potato can also reduce nitrates, but is incapable of oxi- 
dizing salicylic aldehyde. On adding a small amount of potassium 
chlorate, however, the aldehyde is oxidized at the same time that the 
chlorate is reduced. This property of the juice is not lost on boiling. 
In some respects these reactions are similar to those investigated by 
Kastle and Elvove ( 243 ). These authors also observed that the aque- 
ous extract of the potato has the power of reducing nitrates to nitrites 
and that in the presence of certain readily oxidizable organic com- 
pounds, such as formic aldehyde and benzyl alcohol, the quantities 
of nitrite formed are greatly increased. On boiling, the aqueous 
extract of the potato loses its power to reduce nitrates even in the 
presence of readily oxidizable substances. All of these facts point 
to the presence in the potato and in animal tissues of certain fer- 
ments which have the power of effecting the transfer of oxygen from 
a substance rich in this element, such as the chlorate or nitrate, to 
an easily oxidizable substance. According to Abelous ( 3 ) these are 
the oxido-reducing ferments. 
Dony-Henault and Mile. J. van Duuren ( 144 ) have recently investi- 
gated the oxidation of salicylic aldehyde by means of aqueous 
extracts of calf’s liver. According to these observers the methods 
