88 BOTANICAL GAZETTE [FEBRUARY 
upon normal or aerobic respiration. Here is a process which results — 
in the evolution of energy, and gives rise to one important end-— 
product of aerobic respiration, viz., carbon dioxid; yet it early became — 
evident that it could not be counted a process of combustion, at least — 
in any sense in which combustion was then understood. Plainly, — 
the changes that were going on within the organism, which enabled — 
it to give off carbon dioxid when no free oxygen was to be had, could — 
only be a rearrangement of atomic groups within the molecule and : 
the formation of products which were simpler than those from which : 
they arose. 
FERMENTATION. 
The process of fermentation, first thoroughly explored by PASTEUR, — 
of HANSEN and many others, are evidently related to those of respi- 
ration by the nature of the end products and the conditions under — 
which the processes occur. Indeed, when one compares the end — 
to be identical in all respects. Other sorts of fermentation like- © 
wise yield many substances that are found originating in the metab- 
olism of the higher plants. 
We have, then, three modes of energy-release, which are evi- 
dently closely related, if not identical; aerobic respiration, anaerobic 
respiration, and fermentation. Their relations, so far as was known 
in 1898, were stated by Prerrer in his Pflanzenphysiologie and — 
need not be reviewed. 
THE COURSE OF RESPIRATION. 
In translating that work (p. 519) Ewarr wrote: “The actu 
course ine — — the protoplast is quite obscure.” PFEFFER 
Perhaps you will say, to foresee rather than to see—but hypothesis 
must outrun demonstration. The advances to which we are ind 
ae for — Lapsicas! are in three pee first, aa chemistry of 
