September 6, 1912] 



SCIENCE 



291 



seems more justifiable than such an infer- 

 ence. 



But physicists show us movements of a 

 precisely similar character in substances 

 which no one by any stretch of imagina- 

 tion can regard as living; movements of 

 oil drops, of organic and inorganic mix- 

 tures, even of mercury globules, which are 

 indistinguishable in their character from 

 those of the living organisms we have been 

 studying: movements which can only be 

 described by the same term amoeboid, yet 

 obviously produced as the result of purely 

 physical and chemical reactions causing 

 changes in surface tension of the fluids 

 under examination. It is therefore cer- 

 tain that such movements are not specific- 

 ally "vital," that their presence does not 

 necessarily denote "life." And when we 

 investigate closely even such active move- 

 ments as those of a vibratile cilium or a 

 phenomenon so closely identified with life 

 as the contraction of a muscle, we find that 

 these present so many analogies with 

 amoeboid movements as to render it cer- 

 tain that they are fundamentally of the 

 same character and produced in much the 

 same manner. Nor can we for a moment 

 doubt that the complex actions which are 

 characteristic of the more highly differen- 

 tiated organisms have been developed in 

 the course of evolution from the simple 

 movements characterizing the activity of 

 undifferentiated protoplasm ; movements 

 which can themselves, as we have seen, be 

 perfectly imitated by non-living material. 

 The chain of evidence regarding this par- 

 ticular manifestation of life — movement — 

 is complete. Whether exhibited as the 

 amosboid movement of the proteus animal- 

 cule or of the white corpuscle of our blood ; 

 as the ciliary motion of the infusorian or 

 of the ciliated cell; as the contraction of a 

 muscle under the governance of the will, 

 or as the throbbing of the human heart 



responsive to every emotion of the mind, 

 we can not but conclude that it is alike 

 subject to and produced in conformity 

 with the general laws of matter, by agen- 

 cies resembling those which cause move- 

 ments in lifeless material. 



It will perhaps be contended that the 

 resemblances between the movements of 

 living and non-living matter may be only 

 superficial, and that the conclusion regard- 

 ing their identity to which we are led will 

 be dissipated when we endeavor to pene- 

 trate more deeply into the working of living 

 substance. For can we not recognize along 

 with the possession of movement the pres- 

 ence of other phenomena which are equally 

 characteristic of life and with which non- 

 living material is not endowed? Promi- 

 nent among the characteristic phenomena 

 of life are the processes of assimilation 

 and disassimilation, the taking in of food 

 and its elaboration. These, surely, it may 

 be thought, are not shared by matter which 

 is not endowed with life. Unfortunately 

 for this argument, similar processes occur 

 characteristically in situations which no 

 one would think of associating with the 

 presence of life. A striking example of 

 this is afforded by the osmotic phenomena 

 presented by solutions separated from one 

 another by semipermeable membranes or 

 films, a condition which is precisely that 

 which is constantly found in living matter. 



It is not so long ago that the chemistry 

 of organic matter was thought to be en- 

 tirely different from that of inorganic sub- 

 stances. But the line between inorganic 

 and organic chemistry, which up to the 

 middle of the last century appeared sharp, 

 subseqitently became misty and has now 

 disappeared. Similarly the chemistry of 

 living organisms, which is now a recog- 

 nized branch of organic chemistry, but 

 used to be considered as so much outside 

 the domain of the chemist that it could 



