THE PRESIDENTIAL ADDRESS 5 
chemist touches living matter it immediately becomes dead matter 
would also have been justified. A very distinguished organic 
chemist, long since dead, said to me in the late eighties: ‘ The 
chemistry of the living? That is the chemistry of protoplasm ; 
that is superchemistry ; seek, my young friend, for other ambitions.’ 
Research, however, during the present century, much of which has 
been done since the Association last met in Leicester, has yielded 
knowledge to justify the optimism of the few who started to work in 
those days. Were there time, I might illustrate this by abundant 
examples ; but I think a single illustration will suffice to demon- 
strate how progress during recent years has changed the outlook for 
biochemistry. I will ask you to note the language used thirty 
years ago to describe the chemical events in active muscle and 
compare it with that used now. In 1895 Michael Foster, a physio- 
logist of deep vision, dealing with the respiration of tissues, and in 
particular with the degree to which the activity of muscle depends 
on its contemporary oxygen supply, expounded the current view 
which may be thus briefly summarised. ‘The oxygen which enters 
the muscle from the blood is not involved in immediate oxidations, 
but is built up into the substance of the muscle. It disappears into 
some protoplasmic complex on which its presence confers instability. 
This complex, which like all living substance, is to be regarded as 
incessantly undergoing changes of a double kind, those of building 
up and those of breaking down. With activity the latter predomi- 
nates, and in the case of muscle the complex in question explodes, 
as it were, to yield the energy for contraction. ‘ We cannot yet 
trace,’ Foster comments, ‘ the steps taken by the oxygen from the 
moment it slips from the blood into the muscle substance to the 
moment when it issues united with carbon as carbonic acid. The 
whole mystery of life lies hidden in that process, and for the present 
we must be content with simply knowing the beginning and the 
end.’ What we feel entitled to say to-day concerning the respira- 
tion of muscle and of the events associated with its activity requires, 
as I have suggested, a different language, and for those not interested 
in technical chemical aspects the very change of language may yet 
be significant. The conception of continuous building up and 
continuous breakdown of the muscle substance as a whole, has but 
a small element of truth. The colloidal muscle structure is, so to 
speak, an apparatus, relatively stable even as a whole when meta- 
bolism is normal, and in essential parts very stable. ‘The chemical 
reactions which occur in that apparatus have been followed with a 
completeness which is, I think, striking. It is carbohydrate stores 
distinct from the apparatus (and in certain circumstances also fat 
stores) which undergo steady oxidation and are the ultimate sources 
of energy for muscular work. Essential among successive stages in 
