January 1, 1904.] 



SCIENCE. 



19 



as a working hypothesis is a marvelous 

 stimulus. But it did not remain a working 

 hypothesis. 



Men of letters with a transcendental 

 bent of mind have turned it soon into a 

 philosophical system and have extended it 

 to regions which can never become the 

 domain of natural science. Some of the 

 extravagances proclaimed in the name of 

 the mechanical theory brought undeserved 

 discredit upon it. I need only to remind 

 you of the statement that ideas are secreted 

 by the nerve cells just as urine is secreted 

 by the kidney epithelium. Assertions of 

 this kind initiated a reaction against the 

 entire theory. The theory of natural selec- 

 tion by Darwin, which, during its rise, lent 

 its glory to our theory, since in the minds 

 of the literary public the two were nat- 

 urally linked together, subsequently also 

 brought some discredit to it during its slow 

 descent in the favor of that public. 

 Furthermore, the very incessant activity in 

 the investigation of biological problems 

 which was stimulated by the mechanical 

 theory soon brought out the unmistakable 

 fact that, so far, comparatively only a 

 small fraction of life phenomena are acces- 

 sible to interpretation by the physics and 

 chemistry of our day, and the enthusiastic 

 originators of the mechanical theory have 

 inadvertently proclaimed that the physics 

 and chemistry of their day would explain 

 all life phenomena. What a failure! say 

 now the growing number of vitalists, or 

 'neo vitalists,' as they choose to call them- 

 selves. Since the middle of the eighties 

 of the last century a reaction set in against 

 the mechanical theory. In all branches of 

 biology an increasing number of writers of 

 first standing are coming out, veiled or 

 open, against the mechanical theory of life. 

 We meet them in physiological chemistry, 

 in general biology, and we meet them in the 

 writings on medicine, the science as well as 

 the practice of medicine. We meet them 



in the writings on the very subjects I am 

 going to discuss befoi'e you, on the subjects 

 of the production of lymph and formation 

 of oedema. And withal the vitalism of our 

 day is not such a modest or conservative 

 creation .as the prefix 'neo' would lead us 

 to believe. For instance, because only cer- 

 tain substances are absorbed within the 

 intestines, a selection that can not be ex- 

 plained by the laws of diffusion and osmosis 

 as we know them to-day, it is assumed by 

 some writers that the epithelium of the in- 

 testinal mucosa has a selective power. But, 

 instead of considering this assumption 

 merely as a temporary resting place, until 

 we know something more of physics and 

 chemistry, the conclusion is drawn by 

 Neumeister, a distinguished physiological 

 chemist, that the epithelium possesses as 

 much sensation, as much judicial power to 

 know what is good for the body, as the 

 nerve cells of the cortex. In what essential 

 respect does this statement difl:er from the 

 one of Carl Vogt, which was quoted above 

 and which had such a shocking effect upon 

 his contemporaries, namely, that there is 

 not one difference between the nerve cells 

 which secrete ideas and the kidney epi- 

 theliiun which excretes urine ? 



The point is that Vogt as well as Neu- 

 meister, though both excellent scientists, 

 have not made their assertions as natural- 

 ists but as philosophers, who are dealing 

 with transcendental problems. The dis- 

 cussion which is going on between the vital- 

 ists and mechanists and which has not only 

 a theoretical but also a very important 

 practical bearing upon many problems in 

 biology and medicine, suffers, in my opin- 

 ion, from a confusion of conceptions with 

 regard to the questions to be answered. 

 Permit me to discuss here the problems of 

 vitalism and mechanism from my own 

 point of view. 



The phenomena of life are apparently 

 different from those of the inorganic world. 



