THE PRESIDENTIAL ADDRESS 3 
which their pigmentary equipment enables these organisms to 
arrest. 
Are we to believe that life still exists in association with systems 
that are much more simply organised than any bacterial cell? The 
very minute filter-passing viruses which, owing to their causal 
relations with disease, are now the subject of intense study, awaken 
deep curiosity with respect to this question. We cannot yet claim 
to know whether or not they are living organisms. In some sense 
they grow and multiply, but, so far as we yet know with certainty, 
only when inhabitants of living cells. If they are nevertheless 
living, this would suggest that they have no independent power of 
obtaining energy and so cannot represent for us the earliest forms 
in which life appeared. At present, however, judgment on their 
biological significance must be suspended. ‘The fullest under- 
standing of all the methods by which energy may be acquired for 
life’s processes is much to be desired. 
In any case every living unit is a transformer of energy however 
acquired, and the Science of Biochemistry is deeply concerned with 
these transformations. It is with aspects of that science that I am 
to deal and if to them I devote much of my address my excuse is 
that since it became a major branch of inquiry Biochemistry has 
had no exponent in the Chair I am fortunate enough to occupy. 
As a progressive scientific discipline it belongs to the present 
century. From the experimental physiologists of the last century 
it obtained a charter, and, from a few pioneers of its own, a promise 
of success ; but for the furtherance of its essential aim that century 
left it but a small inheritance of facts and methods. By its essential 
or ultimate aim I myself mean an adequate and acceptable de- 
scription of molecular dynamics in living cells and tissues. 
pt. 
When this Association began its history in 1831 the first arti- 
ficial synthesis of a biological product was, as you will remember, 
but three years old. Primitive faith in a boundary between the 
organic and the inorganic which could never be crossed, was only 
just then realising that its foundations were gone. Since then, 
during the century of its existence, the Association has seen the 
pendulum swing back and forth between frank physico-chemical 
conceptions of life and various modifications of vitalism. It is 
characteristic of the present position and spirit of science that 
sounds of the long conflict between mechanists and vitalists are just 
now seldom heard. It would almost seem, indeed, that tired of 
fighting in a misty atmosphere each has retired to his tent to 
await with wisdom the light of further knowledge. Perhaps, how- 
ever, they are returning to the fight disguised as Determinist and 
