Annual Address by the President. 
13 
changes. The introduction of certain chemical bodies also exert 
an accelerating or retarding influence ; and phenomena of selective 
action are likewise to be found. 
Many hypotheses have been submitted. Very ingenious explana- 
tions of some of the phases of fermentation are to be found in 
them ; but under the searching light of completer knowledge their 
incompleteness is sooner or later developed. Many of the modern 
theories are little else than translations of the earlier hypotheses 
into terms of modern scientific terminology, so that the later litera- 
ture is laden with modem extensions of the catalytic theory of 
Berzelius, Beaks bioplastic theory, Justus von Liebig’s physical 
theory, the germ theory, etc. 
Interesting and enlightening as some of these theories are their 
full consideration is not within the purpose of this address, the 
limits of which will permit only a brief and incomplete review of 
some of the more modern conceptions of fermentation, to which 
attention is now asked. 
The more recent investigations of the organized and unorganized 
(soluble) ferments has dealt a severe blow to the vitalistic theory 
of fermentation. Hansen’s admirable biological researches upon 
the yeasts, followed by the important investigations of Buchner, 
A. Croft Hill, Emil Fischer, and many others, brought to light 
many interesting hitherto hidden facts; and it now seems clear 
that all the phenomena of fermentation may be explained from a 
purely chemical basis. The so-called organized ferments appear to 
be “active proteids,” and the unorganized ferments, or enzymes, 
are mostly proteid-like bodies presenting great differences in the 
complexity of their chemical structure. 
Hueppe 8 looks upon “active proteid” as “a kind of intermediate 
stage between lifeless ‘nutritional’ proteid and living cells”; that 
it “appears like an anhydride of dead proteid,” inasmuch as hydra- 
tion converts it into an inactive form. Investigations of Bokorny 
and Loew 9 demonstrated the existence of active proteid in many 
plants. Loew 10 speaks of it as reserve protein matter of a highly 
labile nature, and that it differs from all other reserve proteins. 
He called it proto-protein, and suggested that it is the “material 
which, by being converted into organized nucleo-proteids, forms 
living matter.” Protein comprises all kinds of albuminous matter, 
while proteid is used to designate complex compounds of proteins, 
such as nucleins, haemaglobin, etc. Labile chemical compounds 
are unstable bodies which easily undergo chemical change. Labile 
atoms or groups of atoms are atoms or groups of atoms which 
readily migrate from a center of instability to one of stability. 
