Ja^'uauv 23, 190SJ 



jVA TURE 



^85 



humbli: was ihc foundation of the British Museum and its 

 appanaue, the great Museum of Natural History in South 

 Kensington, the gift to the nation of his valuable collec- 

 tions in natural history and other departments by Sir 

 Hans Sloane, a leading London physician in the first half 

 of ihe eighteenth century. 



Aspects of my subject, full of interest, which I can now 

 barely touch upon, are the influence of previous medical 

 or biological training upon the v(;ork of a physicist or 

 chemist, and closely connected with this the extent to 

 which purely physical problems have been approached 

 from the biological side. Call to mind how the central 

 phvsiccd and chemical problem of the eighteenth century, 

 the nature of combustion, was throughout this period 

 intimately associated with the identical physiological 

 problem of respiration, and how John Mayow in the seven- 

 teenth century, approaching the subject from the biological 

 side, reached a conclusion in accord with that fully demon- 

 strated a century later by Lavoisier, who thereby opened 

 a new era for physiology as w^ell as for chemistry. For 

 the lirst time clear light was shed upon the function of 

 respiration, the nature of metabolism, and the sources 

 of animal heat, and such physical interest was attached 

 to ilic study of these physiological phenomena that 

 physicists of the rank of Laplace, in association with 

 Lavoisier, Dulong, W. E. Weber, Magnus, A. C. 

 Becqucrel, Hirn, Regnault, and of course Helmholtz, have 

 all made valuable contributions to the elucidation of these 

 subjects. 



The study of electricity, especially after the physiologist 

 Galvini's epochal discovery, more correctly interpreted by 

 Volta, engaged the attention of physicians and physio- 

 logists scarcely less than that of physicists. The latter 

 became greatly interested in animal electricity, a subject 

 partly cleared up by the physicists Ritter and Nobili, but 

 mainlv by the physiologist Du Bois Reymond. 



There is no more striking illustration of the correlation 

 of two apparently distinct lines of approach to the same 

 problem than the attack from the biological and from the 

 purely physical sides upon the thermodynamic problem, 

 which is as fundamental for biology as for physics. The 

 conception of the principle of conservation of energy was 

 supplied independently and almost simultaneously, on the 

 one hand, by students of the conditions of mechanical 

 work done by the animal machine, and on the other by 

 investigators of technical machines. Much of the essential 

 preliminary study was on the biological side by Boyle, 

 Mayow, Black, and Lavoisier. Mainly from the same 

 side the physician and physicist, Thomas Young, first 

 foriiiulated the modern scientific conception of energy as 

 the power of a material system to do work. Davy and 

 Rumford contributed, and from the physiological side 

 Mohr, Mayer, and Helmholtz, and from the purely physical 

 side, after preliminary work by Poncelet and Sadi-Carnot. 

 Joule, Thomson, and Clausius reached the same grand 

 conception. The first to enunciate clearly and fully the 

 doctrine of the conservation of energy and to measure the 

 unit of mechanical work derived from heat was the 

 physician J. R. Mayer. Joule's work completed the 

 demonstration, but Mayer's name is deservedly attached 

 to this principle by Poincar^ and others, as Lavoisier's is 

 to that of the conservation of mass, and Sadi-Carnot 's 

 to the principle of degradation of energy. As regards this 

 last principle, it is almost as interesting to biologists as 

 to physicists that in the so-called Brunonian movement, 

 discovered by the physician and more eminent botanist 

 Robert Brown, and the subject of interesting physical 

 investigations in recent years, we behold an apparent 

 excention to the principle of degradation of energy, such 

 as Clerk Maxwell pictured as possible to the operations 

 of his sorting demon. 



I must forego further citation of examples of this 

 kind of correlation between the work of physicists and 

 of physiologists, and leave untouched the chemical side, 

 which is much richer in similar illustrations. The signifi- 

 cance to organic chemistry of the synthesis of urea by 

 Wiihlir, and to agricultural chemistry of the bacteriological 

 studies of nitrification in the soil and fixation of nitrogen 

 in plants, will perhaps indicate how large and fascinating 

 1 field I must pass by. 



The light which has transformed the face of modern 

 practical medlclni' came, In the first instance, not from a 



XO. 1905. VOL. 77I 



physician, but from a physicist and chemist, Pasteur. 

 The field of bacteriological study thus disclosed was placed 

 on a firm foundation and thrown open to ready explora- 

 tion by Robert Koch, and thereby that class of diseases 

 most important to the human race, the infectious, became 

 subject in ever-increasing measure to control by man. 

 Thus hygiene and preventive medicine, through their 

 power to check the incalculable waste of human life and 

 health and activities, have come into relations, which have 

 only begun to be appreciated, with educational, political, 

 economic, and other social sciences and conditions, and 

 with the administration of national. State, and municipal 

 governments. It is an especial gratification to record the 

 stimulating recognition of these relationships by the social 

 and economic section of this association, in which was 

 started a year and a half ago a movement for public 

 health, particularly as related to the Federal Government, 

 which has already assumed national significance. 



To the marvellous growth of the medical and other 

 sciences of living beings during the past century, and 

 especially in the last fifty years, physics and chemistry 

 and the application of physical and chemical methods of 

 study have contributed directly and indirectly a very large 

 and ever-increasing share. In many instances there is no 

 telling when or where or how some discovery or new 

 mvention may prove applicable to medical science or art. 

 Who could have dreamed in 1856 that Sir William Perkin's 

 production of the first aniline dye should be an essential 

 link in the development of modern bacteriology, and there- 

 fore in the crusade against tuberculosis and other infectious 

 diseases? As Robert Koch has said, it would have been 

 quite impossible for him to have developed his methods 

 and made his discoveries without the possession of elective 

 dyes for staining bacteria, and colouring agents of no 

 other class have been discovered which can serve as 

 substitutes for the anilines in this regard. And how 

 much assistance these dyes have rendered to the study of 

 the structure and even the function of cells ! If we trace 

 to their source the discovery of Rontgen's rays, which 

 have found their chief practical application in medicine 

 and surgery, we shall find an illustration scarcely less 

 striking. 



No important generalisation in physical science js with- 

 out its influence, often most important, upon biological 

 conceptions and knowledge. I have already referred to 

 the great principles of conservation of mass and of energy 

 which are at the very foundation of our understanding of 

 vital phenomena. Although we cannot now foresee their 

 bearings, we may be sure that the new theories, regard- 

 ing the constitution of what has hitherto been called 

 matter, will, as they are further developed, prove of the 

 highest significance to our conceptions of the organic as 

 well as of the inorganic world. 



The ultimate problems of biology reside in the cell. 

 Whatever the future may hold in store, at the present 

 day only a relatively small part of these problems are 

 approachable bv phvsical or chemical methods, and the 

 day is far distant, if it ever comes, when cellular physio- 

 logy shall be nothing but applied physics and chemistry. 

 We cannot foresee a time when purely observational and 

 descriptive biological studies, which to-day hold the first 

 place, shall not continue to have their value. They re- 

 present the direction which makes the strongest appeal to 

 the great majority of naturalists. The broadest 

 generalisations hitherto attained in biology, the doctrine 

 of the cell as the vital unit and the theory of organic 

 evolution, have come from this biological, as distinguished 

 from physical, direction of investigating living organisms, 

 and were reached bv men with the type of mind of the 

 pure naturalist, who loves the studv of forms, colours, 

 habits, variations, adaptations, inheritances of hvmg 

 beings. 



It is well that the sciences of nature hold out attractions 

 to so manv different types of mind, for the edifice of 

 science is built uo of material which must be drawn from 

 many sources. A quarry opened in the interest of one 

 enriches all of these sciences. The deeper we can lay the 

 foundations and the farther we can penetrate into the 

 nature of things, the closer are the workers drawn 

 together, the clearer becomes their community of purpose, 

 and the more significant to mankind the up-building of 

 natural knowledee. 



