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extremely limited, it is essentially unscientific to say that any pliysiological phe- 

 nomenon is caused by vital force or is an argument in favour of ' vitalism/ and 

 that, if this phraseology is offered as a sufficient description of the phenomenon, 

 its further scientific study is prejudiced because the only terminology which admits 

 of scientific exactitude is excluded. I assert, further, that if the term ' vitalism ' 

 connotes no more in physiology than the term ' living,' its employment does not in 

 any way enlarge our intellectual view of the subject-matter of physiology, andean 

 only be considered either as meaningless tautology or as an expression of faith ; 

 but if the term has some additional, occult, and mystic significance, then its 

 employment is detrimental to the progress of physiology, exerting as obstructive 

 an influence upon the growth of our science as the conception of special creation 

 exerted upon the progress of biology. 



Vitalism is not the only ' ism ' which, perhaps unwittingly, obstructs physio- 

 logical progress ; it is, however, far more worthy of respect than others which I 

 do not propose to particularise, for it is a twig of that lusty tree which, in philo- 

 sophy, still claims the largest share of men's belief. The vitalist, leaving the 

 more solid ground of phjsics and chemistry, enters the realm of metaphysics and 

 there attaches himself to that distinguished circle of idealists whose pedigree 

 extends back to Plato. If, as may be asserted with great confidence, idealism in 

 philosophy will endure as long as thought exists, then it might be expected that 

 vitalism in physiolog-y will never entirely cease. The history of physiology, how- 

 ever, reveals the fluctuating extent of its influence. Potent a century or more 

 ago, vitalism nearly disappeared between 1850 and 1870 under the pressure of the 

 application of physical and chemical methods to physiology ; it revived again 

 towards the century's close, the ripple of a wide-spreading wave of idealistic 

 philosophy. Materialism and idealism have been described by Huxley as appear- 

 ing in the history of philosophy like ' the shades of Scandinavian heroes eternally 

 slaying one another and eternally coming to life again.' Asa phj'siologist, I do 

 not venture to touch however lightly upon this metaphysical duel, since I frankly 

 admit my own incapacity to do so and the particular applicability to my own 

 powers of the words of Gibbon that ' it is much easier to ascertain the appetites 

 of a quadruped than the speculations of a philosopher.' It is therefore without 

 any intention of casting any suspicion of doubt upon the confidence felt as to the 

 persistence of idealism in philosophy, that I suggest that neo-vitalism in physio- 

 logy bears upon its surface the signs of its own decay. One such sign is the 

 circumstance that even its most ardent exponents refuse to follow the lead of this 

 ignis fatuus, but assiduously investigate living processes by the most improved 

 chemical and physical methods ; another is that when any so-called vitalistic 

 aspect of some physiological phenomenon is rendered explicable on physical and 

 chemical lines, the vitalist abandons in this instance his peculiar standpoint. 

 Neo-vitalism has of late thus lost its corrosive character ; it now spreads as a thin 

 but tenacious film over physiological conceptions and is in this way mildly 

 obstructive, but its obstructive viscosity is continually yielding to the accumu- 

 lating mass of the more precise knowledge which it endeavoiirs to obscure. 

 Research along physical and chemical lines into physiological processes is its un- 

 compromising opponent, so that there is every reason for believing with Huxley 

 that the weight and increasing number of those who refuse to be the prey of 

 verbal mystifications have begun to tell. 



The recent history of physiological progress shows that investigations confined 

 to the study of physical and chemical processes have been the one fruitful source of 

 physiological knowledge. It would be impossible to give even a brief survey of the 

 chief results which have, during the last twenty years, been thus obtained. Out 

 of the enormous wealth of material I select one of great importance and promise. 

 It is that of the constitution of the nitrogenous compound familiai'ly known as 

 proteid, which from its close association with protoplasm, the physical basis of life, 

 has a fundamental significance and has therefore attracted the attention of many 

 competent investigators. Important researches have been made on this subject 

 by physiological chemists, notably Hofmeister and Kossel, and at the present time 

 the subject is also being studied by one of the ablest organic chemists of the day, 



