568 
physiological journals of to-day contrast very markedly with 
those of thirty, twenty, or even ten years ago. The sister 
science of chemical pathology is making similar rapid strides. 
In some universities the importance of biological chemistry is 
recognised by the foundation of chairs which deal with that 
subject alone ; and though in the United Kingdom, owing 
mainly to lack of funds, this aspect of the advance of science is 
not very evident, there are signs that the date cannot be far 
distant when every well-equipped university or university college 
will follow the example set us at many seats of learning on the 
Continent and at Liverpool. 
With these introductory remarks let me now proceed to 
describe what appear to me to be the main features of chemical 
physiology at the present time. 
The first point to which I shall direct your attention is the 
rapid way in which chemical physiology is becoming an exact 
science. Though it is less than twenty years since I began to 
teach physiology, I can remember perfectly well a time when 
those who devoted their work to the chemical side of the science 
might almost be counted on the fingers of one hand, and when 
chemists looked with scarcely veiled contempt on what was at 
that time called physiological chemistry; they stated that 
physiologists dealt with messes or impure materials, and there- 
fore anything in the nature of correct knowledge was not 
possible. There was'a good deal of truth in these statements, 
and if physiologists to-day cannot quite say that they have 
changed all that, they can at any rate assert with truth that 
they are changing it. This is due toa growing rapprochement 
between chemists and physiologists. Many of our younger 
physiologists now go through a thorough preliminary chemical 
training ; and on the other hand there is a growing number of 
chemists—of whom Emil Fischer may be taken as a type—who 
are beginning to recognise the importance of a systematic 
study of substances of physiological interest. A very striking 
instance of this is seen in the progress of our knowledge of the 
carbohydrates, which has culminated in the actual synthesis of 
several members of the sugar group. Another instance is seen 
in the accurate information we now possess of the constitution 
of uric acid. When Miescher began his work on the chemical 
composition of the nuclei of cells, and separated from them 
‘the material he called nuclein, he little foresaw the wide prac- 
tical application of his work. We now know that it is in the 
metabolism of cell-nuclei that we have to look for the oxidative 
formation of uric acid and other substances of the purine family. 
Already the chemical relationships of uric acid and nuclein 
have taught practical physicians some of the secrets that under- 
lie the occurrence of gout and allied disorders. 
With the time at my disposal, it would be impossible to 
discuss all the chemico-vital problems which the physiologists 
of the present day are attempting to solve, but there is one 
subject at which many of them are labouring which seems to 
me to be of supreme importance—I mean the chemical consti- 
tution of proteid or albuminous substances. Proteids are pro- 
duced only in the living laboratory of plants and animals ; 
proteid metabolism is the main chemical attribute of a living 
thing ; proteid matter is the all-important material present in 
protoplasm. But in spite of the overwhelming importance of 
the subject, chemists and physiologists alike have far too long 
fought shy of attempting to unravel the constitution of the 
proteid molecule. This molecule is the most complex that is 
known; it always contains five, and often six, or even seven 
elements. The task of thoroughly understanding its composi- 
tion is necessarily vast, and advance slow. But little by little 
the puzzle is being solved, and this final conquest of organic 
chemistry, when it does arrive, will furnish physiologists with 
new light on many of the dark places of physiological science. 
The revival of the vitalistic conception in physiological work 
appears to me a retrograde step. To explain anything we are 
not fully able to understand in the light of physics and chemistry 
by labelling it as vital or something we can never hope to 
understand is a confession of ignorance, and, what is still more 
harmful, a bar to progress. It may be that there is a special 
force in living things that distinguishes them from the inorganic 
world. If this is so, the laws that regulate this force must be 
discovered and measured, and I have no doubt that those laws 
when discovered will be found to be as immutable and regular 
as the force of gravitation. I am, however, hopeful that the 
scientific workers of the future will discover that this so-callel 
vital force is due to certain physical or chemical properties of 
living matter which have not yet been brought into line with 
the known chemical and physical laws that operate in the 
no. 1718, VOL. 66] 
NATURE 
[OcToBER 2, 1902 
inorganic world, but which as our knowledge of chemistry and 
physics increases will ultimately be found to be subservient to 
such laws. 
Let me take as an example the subject of osmosis. The laws 
which regulate this phenomenon through dead membranes are 
fairly well known and can be experimentally verified ; but in the 
living body there is some other manifestation of force which 
operates -in such a way as to neutralise the known force of 
osmosis. Is it necessary to suppose that this force is a new 
one? May it not rather be that our much vaunted knowledge 
of osmosis is not yet complete? It is quite easy to understand 
why a dead and a living membrane should behave differently 
in relation to substances that are passing through them. The 
molecules of the dead membrane are, comparatively speaking, 
passive and stable ; the molecules in a membrane made of living 
cells are in a constant state of chemical integration and dis- 
integration ; they are the most unstable molecules we know. 
Is it to be expected that such molecules would allow water, or 
substances dissolved in water, to pass between them and remain 
entirely inactive? The probability appears to me to be all the 
other way; the substances passing, or attempting to pass, 
between the molecules will be called upon to participate in the 
chemical activities of the molecules themselves, and in the 
building up and breaking down of the compounds so formed 
there will be a transformation of chemical energy and a libera- 
tion of what looks like a new force. Before a physicist decides 
that his knowledge of osmosis is final, let him attempt to make 
a membrane of some material which is in a state of unstable 
chemical equilibrium, a state in some way comparable to what 
is called metabolism in living protoplasm. I cannot conceive 
that such a task is insuperable, and when accomplished, and the 
behaviour of such a membrane in an osmometer or dialyser is 
studied, I am convinced that we shall find that the laws of 
osmosis as formulated for such dead substances as we have 
hitherto used will be found to require revision. 
Such an attitude in reference to vital problems appears to be 
infinitely preferable to that which too many adopt of passive 
content, saying the phenomenon is vital and there is an end 
of it. ; 
When fa scientific man says this or that vital phenomenon 
cannot be explained by the laws of chemistry and physics, and 
therefore must be regulated by laws of some other nature, he 
most unjustifiably assumes that the laws of chemistry and physics 
have all been discovered. Ie forgets, for instance, that such 
an important detail as the constitution of the proteid molecule 
has still to be made out. 
The recent history of science gives an emphatic denial to such 
a supposition. All my listeners have within the last few years 
seen the discovery of the Rontgen rays and the modern develop- 
ment of wireless telegraphy. On the chemical side we have 
witnessed the discovery of new elements in the atmosphere and 
the introduction of an entirely new branch of chemistry called 
physical chemistry. With such examples ready to our hands, 
who can say what further discoveries will not shortly be made, 
even in such well-worked fields as chemistry and physics ? 
The mention of physical chemistry brings me to what I may 
term the second head of my discourse, the second striking 
characteristic of modern chemical physiology ; this is the in- 
creasing importance which physiologists recognise in a study of 
inorganic chemistry. The materials of which our bodies are 
composed are mainly organic compounds, among which the 
proteids stand out as preeminently important ; but everyone 
knows there are many substances of the mineral or inorganic 
kingdom present in addition. I need hardly mention the im- 
portance of water, of the oxygen of the air, and of salts like 
sodium chloride and calcium phosphate. 
The new branch of inorganic chemistry called physical 
chemistry has given us entirely new ideas of the nature of 
solutions, and the fact that electrolytes in solution are broken 
up into their constituent ions is one of fundamental importance. 
One of the many physidlogical aspects of this subject is seen in 
a study of the action of mineral salts in solution on living 
organisms and parts of organisms. Many years ago Dr. Ringer 
showed that contractile tissues (heart, cilia, &c.) continue to 
manifest their activity in certain saline solutions. Howell goes 
so far as to say, and probably correctly say, that the cause ot the 
rhythmical action of the heart is the presence of these inorganic 
substances in the blood or lymph which usually bathes it. The 
subject has more recently been taken up by Loeb and his 
colleagues at Chicago ; they confirm Ringer’s original state- 
ments, but interpret them now as ionic action. Contractile 
