466 



NA TURE 



[September 14, 1893 



f 



self, in common witli TrevirAnus and all ihe b;o!oi;icaI teachers 

 of his time, was a vitalist, i.e. he regarded what was then called 

 the vis vilalis — the Lebenskraft — as something capable of being 

 correlated with the physical forces ; and as a necessary conse- 

 quence held thit phenomena should be classified or distin- 

 guished, according to the forces which produced them, as vital 

 or physical, and that all those processes — that is groups or series 

 of phenomena in living organisms— for which, in the then very 

 imperfect knowledge which existed, no obvious physical expla- 

 nation could be found, were sufficiently explained when they 

 were slated to be dependent on so-called vital laws. But during 

 the period of Miiller's greatest activity times were changing, and 

 he was changing with them. During his long career as professor 

 at Berlin he became more and more objective in his tendencies, 

 and exercised an influence in the same direction on the men of 

 the next generation, teaching them that it was better and more 

 useful to observe than to philosophise ; so that, although he 

 himself is truly regarded as the last of the vitalists — for he was 

 a vitalist to the last — -his successors were adherents of what has 

 been very inadequately designated the mechanistic view of the 

 phenomena of life. The change thus brought about just be- 

 fore the middle of this century was a revolution. It was not a 

 substitution of one point of view for another, but simply a frank 

 abandonment of theory for fact, of speculation for experiment. 

 Physiologists ceased to theorise because they found something 

 better to do. May I try to give you a sketch of this era of 

 progress ? 



Great discoveries as to the structure of plants and animals 

 had been made in the course of the previous decade, those es- 

 pecially which had resulted from the introduction of the micro- 

 scope as an instrument of research. By its aid Schwann had 

 been able to show that all organised structures are built up of 

 those particles of living substance which we now call cells, and 

 recognise as the seats and sources of every kind of vital activity. 

 Hugo Mohl, working in another direction, had given the name 

 " protoplasm " to a certain hyaline substance which forms the 

 lining of the cells of plan s, though no one as yet knew that it 

 was the essential constituent of all living structures — the basis 

 of life no less in animals than in plants. And, finally, a new 

 branch of study— histology — founded on observations which the 

 microscope had for the first time rendered possible, had come 

 into existence. Bowman, one of the earliest and most successful 

 cultivators of this new science, called it physiological anatomy,' 

 and justified the title by the very important inferences as to the 

 secreting function of epithelial cells and as to the nature of mus- 

 cular contraction, which he deduced from his admirable ana- 

 tomical researches. From structure to function, from micro- 

 scopical observation to physiological experiment, the transition 

 was natural. Anatomy was able to answer some questions, but 

 asked many more. Fifty years ago physiologists had micro- 

 scopes but had no laboratories. English physiologists — Bow- 

 man, Paget, Sharpey — were at the same time anatomists, and 

 in Berlin Johannes Miiller, along with anatomy and physiology, 

 taught comparative anatomy and pathology. But soon that 

 specialisation which, however much we may regret its necessity, 

 is an essential concomitant of progress, became more and more 

 inevitable. The structural conditions on which the processes of 

 life depend, had become, if not known, at least accessible to in- 

 vestigation ; but very little indeed had been ascertained of the 

 nature of the processes themselves — so little indeed that if at 

 this moment we could blot from the records of physiology the 

 whole of the information which had been acquired, say in 

 1840, the loss would be difficult to trace — not that the pre- 

 viously known facts were of little value, but because 

 every fact of moment has since been subjected to experi- 

 mental verification. It is for this reason that, without 

 any hesitation, we accord to Miiller and to his successors 

 Biiicke, du Bois-Reymond, Helmholtz, who were his pupils, 

 and Ludwig, in Germany, and to Claude Bernard- in 

 France, the title of founders of our science. For it is 

 the work which they began at that remarkable time (1845-55), 

 and which is now being carried on by their pupils or their 

 pupils' pupils in England, America, France, Germany, Den- 

 mark, Sweden, Italy, and even in that youngest contributor to 

 the advancement of science, Japan, that physiology has been 



' Tile first part of the Physiological Anatomy appeared in 1843. It was 

 concluded in 1S56. 



'^ It is worthy of note that these five distinguished men were merely 

 contemporaries ; Ludwig graduated in 1839, Bernard in 1843, the otherthree 

 between those dates. Three survive— Helmholtz, Ludwig, du Bois-Rey- 

 mond. 



gradually built up 10 whatever completeness it has at present | 

 attained. 3 



What were the conditions which brought about this great 

 advance which coincided with the middle of the century? There 

 is but little difficulty in answering the question. I have already 

 said that the change was not one of doctrine, but of method. 

 There was, however, a leading idea in the minds of those who 

 were chiefly concerned in bringing it about. That leading 

 notion was that, however complicated may be the conditions 

 under which vital energies manifest themselves, they can be 

 split into processes which are identical in nature with those of 

 the non-living world, and, as a corollary to this, that the 

 analysing of a vital process into its physical and chemical con- 

 stituents, so as to bring these constituents into measurable 

 relation with physical or chemical standards, is the only mode 

 of investigating them which can lead to satisfactory results. 



There were several circumstances which at that time tended 

 to make the younger physiologists (and all of the men to whom 

 I have just referred were then young) sanguine, perhaps too 

 sanguine, in the hope that the applicaticm of experimental 

 methods derived from the exact sciences would afford solutions 

 of many physiological problems. Oneof these was the progress 

 which had been made in the science of chemistry, and par- 

 ticularly the discovery that many of the compounds which before 

 had been regarded as special products of vital processes could 

 be produced in the laboratory, and the more complete know- 

 ledge which had been thereby acquired of their chemical con- 

 stitutions and relations. In like manner, the new school 

 profited by the advances which had been made in physics, 

 partly by borrowing from the physical laboratory various im- 

 proved methods of observing the phenomena of living beings, 

 but chiefly in consequence of the direct bearing of the crown- 

 ing discovery of that epoch (that of the conservation of energy) 

 on the discussions which then took place as to the relations 

 between vital and physical forces ; in connection w ith which it 

 may be noted that two of those who (along with Mr. Joule and 

 your President at the last Nottingham meeting) took a pro- 

 minent part in that discovery — Helmholtz and J. P. Mayer — 

 were physiologists as much as they were physicists. I will not 

 attempt even to enumerate the achievements of that epoch of 

 progress. I may, however, without risk of wearying you, in- 

 dicate the lines along which research at first proceeded, and 

 draw your attention to the contrast between then and now. At 

 present a young observer who is zealous to engage in reseaich 

 finds himself provided with the most elaborate means of in- 

 vestigation, the chief obstacle to his success being that Ihe 

 problems which have been left over by his predecessors are of 

 extreme difficulty, all of the easier questions having been worked 

 out. There were then also difficulties, but of an entirely 

 different kind. The work to be done was in itself easier, but 

 the means for doing it were wanting, and every investigator had 

 to depend on his own resources. Consequently the successful 

 men were those who, in addition to scientific training, pos- 

 sessed the ingenuity to devise and the skill to carry out methods 

 for themselves. The work by which du Bois-Reymond laid 

 the foundation of animal electricity would not have been pos- 

 sible had not its author, besides being a trained physicist, known 

 how to do as good work in a small room in the upper floor of 

 the old University building at Berlin as any which is now done 

 in his splendid laboratory. Had Ludwig not possessed 

 mechanical aptitude, in addition to scientific knowledge, he 

 would have been unable to devise the apparatus by which he 

 measured and recorded the variations of arterial pressure (1848), 

 and verified the principles which Young had laid dov\n thirty 

 years before as to the mechanics of the circulation. Nor, lastly, 

 could Helmholtz, had he not been a great deal more than 

 a mere physiologist, have made those measurements of the time- 

 relations of muscular and nervous responses to stimulation, which 

 not only afford a solid foundation for all that has been done 

 since in the same direction, but has served as models of physio- 

 logical experiment, and as evidence that perfect work was pos- 

 sible and was done by capable men, even when there were no 

 physiological laboratories. 



Each of these examples relates to work done within a year or 

 two of the middle of the century.' If it were possible to enter 



' The " Untersuchungcn fiber thierische Electriciliit " appeared in 1848 ; 

 Ludwig's researches on the circulation, which included the fir-t d'scnption 

 of the " kymograph " and served as the foundation of the "graphic 

 meihod" in 1847; Helmholtz's research on the propagation in irolor 

 nerves in 1851. 



NO. 1 246, "OI, 48] 



