August 8, 1913] 



SCIENCE 



175 



more or less intimate contact witli both fields, 

 may be drawn toward the one or the other 

 camp. 



In the interpretation of life phenomena, we 

 can not, of course, escape from the domain of 

 physics and chemistry; the living body is 

 material, and the fundamental physical laws 

 of the conservation of matter and energy hold 

 there as in the inanimate world. In the trans- 

 formations that take place in organisms, there 

 is no evidence whatsoever known to me of or 

 the least indication that new matter has ap- 

 peared or new energy been created. We are 

 constrained therefore, if we must postulate a 

 vital force, to conclude that it is a new form, 

 of energy developed out of the other energy 

 forms and transformable into them again. 

 Since we know nothing about such a special 

 life form of energy, but only the energy of 

 inanimate matter, there has always seemed to 

 me no value in its assumption, since the anal- 

 ysis must always proceed from the known to 

 the unknovm and be expressed in terms of the 

 physics and chemistry of the organism. If in 

 course of time it becomes apparent that an- 

 other energy form exists in living organisms, 

 it will then be time enough to discuss it; for 

 the present I do not believe it helps to intro- 

 duce it. 



In all analysis of life phenomena, very 

 fundamental it seems to me is the analysis of 

 life conditions, those absolutely essential for 

 its manifestation, and you will, I know, par- 

 don my introducing here so elementary a 

 matter as their enumeration. They are: (1) 

 Food-stuffs, i. e., the necessary chemical con- 

 ditions; (2) oxygen; (3) water; (4) heat, i. e., 

 the adequate temperature; (5) pressure. Out 

 of these, together with a few more that rest 

 upon them as a basis — (6) protection, of diver- 

 sified forms; (7) elimination of useless mate- 

 rial; (8) formation of new individuals as 

 centers of organic transformation — are com- 

 pounded the fundamental life activities, of 

 the higher organisms at least. It is hardly 

 necessary to insist upon the broad application 

 of the above thesis. Following through the 

 sum total of the activities of an organism — 

 and I would include its structure as but the 



partial expression of these same activities — 

 untangling in your analysis the complex that 

 they form you come back to the fundamental 

 categories of life manifestation enumerated 

 above and the conditions that underlie them. 

 There is, of course, nothing fundamentally 

 different in the manifestation of life under 

 the given necessary conditions and a chemical 

 or physical reaction. To take a simple exam- 

 ple, the rusting of iron. Given the necessary 

 conditions, namely, the presence of water, oxy- 

 gen, some acid, I am told, such as carbonic 

 acid, and of course iron, under an adequate 

 temperature, and the reaction will proceed at 

 a given rate. Under somewhat different and 

 more complex conditions, the presence of some 

 other acid or salt, and with less pure iron, the 

 reaction will proceed more rapidly. But I am 

 venturing on rather dangerous ground and 

 must withdraw. 



There are two aspects of life manifestation 

 which I desire to mention and which will 

 introduce the subject that I chose to discuss 

 with you. The first of these is the continuity 

 of life and all that it includes — growth and 

 reproduction. This in itself would possibly 

 be regarded as more intimately characteristic 

 of life, but I believe that if we were to stop to 

 analyze it out, we would find nothing distinc- 

 tive in mere continuity. One might, I think, 

 find illustrations of purely physico-chemical 

 reactions taking place in the earth's crust 

 to-day that have been proceeding since its 

 foundations. It is that in organisms insuring 

 the continuity which is peculiarly biological. 

 The molding of the life activities of organisms 

 to a more or less specific environment supply- 

 ing the necessary life conditions so that en- 

 vironment and organism constitute an inter- 

 related system of more or less complexity, is 

 the second aspect I made reference to, and 

 adaptation^ appeals to me as a second very 

 fundamental fact in biology. Of the truth of 

 this and the great diversity of patterns in 

 which life activities and environment are 

 interwoven in different organisms, you doubt- 

 less know better than I who have largely only 



' The term is employed in the broad sense, and 

 as a passive instead of active noun. 



