160 SECTIONAL ADDRESSES. 



tubes whicli are branched and of varying degrees of elasticity, of diameters 

 whicb in the same system range from several centimetres down to a few 

 microns, and these subject to variations, we can expect little help from 

 orthodox physics, which is not in the habit of working with so many 

 independent variables. 



It follows that much of our physics, if it is worth calling that, must of 

 necessity be empirical for the present. This is not a defect in physiology 

 — ^it is a defect in physical knowledge. 



Chemistry and physiology having both originally sprung from the 

 art and practice of medicine, it is little matter for surprise that such a 

 rich harvest has been reaped by their reunion in the form of biochemistry. 

 Although these developments were foreshadowed by the intuition, if not 

 by the actual achievements, of the iatro-chemists of the sixteenth century, 

 little advance was possible until chemistry had, by separation from medicine, 

 established its position as an independent science. So that it was not 

 until about 1840 that organic chemistry and biochemistry were able, 

 chiefly owing to the inspiration of Liebig, to make rapid progress, at least 

 on the Continent. There is probably no branch of chemistry that is 

 entirely without interest to physiology, but of course preference must 

 always be given to organic and physical chemistry. It is significant that 

 at the present time a steadily increasing number of young highly trained 

 organic chemists consider it worth their while to turn to biochemistry ; 

 their welcome entry into our ranks gives us fresh hope and faith in our 

 future, as well as in theirs. Already one can pdint to many achievements 

 of the organic chemist applying himself to our problems, the work of 

 Fischer on the carbohydrates, purine bodies and proteins and amino- 

 acids, the more recent work on adrenaline, the identification of carnosine, 

 glutathione, the structure of thyroxine and the natural bases, of which 

 histamine threatens to rival or even to eclipse lactic acid in its importance 

 to the physiologist. As is usually the case, rapid developments in bio- 

 chemistry have followed improvements of technique ; the advances in 

 micro-methods of analysis, without which insulin would probably not have 

 been discovered, or the constitution of thyroxin made known, have played 

 a very important part ; the same applies to the whole subject of physical 

 chemistry, much of which, like colloid chemistry and the theories of buffer 

 action, has been built up in response to biochemical requirements. Since 

 the central problems of biochemistry are dynamical, most of its subject- 

 matter must be treated from that standpoint, and here again the debt 

 to physical chemistry must be recognised, particularly in regard to 

 the study of enzyme action, and more recently of iuterfacial and 

 membrane equilibria, of the molecular structure of surfaces, and of the 

 phenomena of activation and the thermodynamics of oxidation-reduction 

 phenomena. 



Whether a biochemist should be primarily a chemist or a biologist is 

 a question which has been much debated in private, though little in public. 

 Personally I see no reason why he should not be both. If he must have 

 one label, it is better that of the chemist, provided always that the bio- 

 chemist works in the closest possible association with the physiologist. 

 This is most essential if both are not to be deprived of much valuable 

 interchange of ideas and, on a lower plane, of materials and apparatus. 



