NATURE 



[September 5, 1912 



antithetical. Strictly and literally, the words animate 

 and inanimate express the presence or absence of 

 '■ soul " ; and not infrequently we find the terms " life " 

 and "soul" erroneously employed as if identical. But 

 it is scarcely necessary for me to slate that the remarks 

 1 have to make regarding "life" must not be taken 

 lo apply to the conception to which the word "soul" 

 is attached. 



Problems of Life arc Problems oj Mailer. 

 The fact that the formation of such a conception is 

 only possible in connection with life, and that the 

 growth and elaboration of the conception has only 

 been possible as the result of the most complex pro- 

 cesses of life in the most complex of living organisms, 

 has doubtless led to a belief in the identity of life with 

 soul. But unless the use of the expression "soul" is 

 extended to a degree which would deprive it of all 

 special significance, the distinction between these terms 

 liiust be strictly maintained. For the problems of life 

 are essentially problems of matter ; we cannot conceive 

 of life in the scientific sense as existing apart from 

 matter. The phenomena of life are investigated, and 

 can only be investigated, by the same methods as all 

 other phenomena of matter, and the general results 

 of such investigations tend to show that living beings 

 are governed by laws identical with those which govern 

 inanimate matter. The more we study the manifesta- 

 tions of life, the more we become convinced of the 

 truth of this statement and the less we are disposed 

 to call in the aid of a special and unknown form of 

 energy to explain those manifestations. 



Phenomena Indicative oj Life: Movement. 

 The most obvious manifestation of life is " spon- 

 taneous " movement. We see a man, a dog, a bird 

 move, and we know that they are alive. We place 

 a drop of pond water under the microscope, and see 

 numberless particles rapidly moving within it; we 

 affirm that it swarms with "life." We notice a small 

 mass of clear slime changing its shape, throwing out 

 projections of its structureless substance, creeping from 

 one part of the field of the microscope to another. 

 We recognise that the slime is living ; we give it a 

 name — Amoeba Umax — the slug amoeba. We observe 

 similar movements in individual cells of our own body ; 

 in the white corpuscles of our blood, in connective 

 tissue cells, in growing nerve cells, in young cells 

 evervwhere. We denote the similarity between these 

 movements and those of the amoeba by employing the 

 descriptive term " amceboid " for both. We regard 

 such movements as indicative of the possession of 

 "life"; nothing seems more justifiable than such an 

 inference. 



Similarily of Movements in Living and Non-living 

 Matter. 

 ■ But physicists - show us movements of a precisely 

 similar character in substances which no one by any 

 stretch of imagination can regard as living ; move- 

 ments of oil drops, of organic and inorganic mixtures, 

 even of mercury globules, which are indistinguishable 

 in their ch.iracter from those of the living organisms 

 we have been studying : movements which can only 

 be described by the same term amceboid, yet obviously 

 produced as the result of purely phvsical and chemical 

 reactions causing changes in surface tension of the 

 fiuids under examination.' It is therefore certain that 



" G. Quincke, "Annnl. d. Physik. v. Chem.," 1S70 and 1S88. 



" The causation not only of movements but of various other manifesta- 

 tions of life by alterations in surface tension of living substance is ably dealt 

 with by A. B. Macallum in a recent article in Asher and .Spiro's " Ergebnisse 

 der Phjsiologie," igii. Macallum has described an accumulation of 

 potassium salts at the more active surfaces of the protoplasm of many cells, 

 and correlates this with the production of cell-activity bv the eflfect of such 

 accumulation upon the surface tension. The literature of the subject will be 

 found in this article. 



NO. 2236, VOL. 90] 



such movements are not specifically " vital," that thetr 

 presence does not necessarily denote "life." And when 

 we investigate closely even such active movements 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 certain that thej- 

 are fundamentally of the same character and produced 

 in much the same manner.' Nor can we for a moment 

 doubt that the comple.x actions which are characteristic 

 of the more highly differentiated organisms have been 

 developed in the course of evolution from the simple 

 movements characterising the activity of un- 

 differentiated protoplasm ; movements which can 

 themselves, as we have seen, be perfectly imitated 

 by non-living material. The chain of evidence 

 regarding this particular manifestation of life — move- 

 ment — is complete. Whether exhibited as the amoeboid 

 movement of the proteus animalcule 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 cannot but conclude that it 

 is alike subject to and produced in conformity with the 

 general laws of matter, by agencies resembling those 

 which cause movements in lifeless material. = 



Assimilation and Disassiniilation. 

 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 endeavour to penetrate more deeply into the 

 working of living substance. For can we not recog- 

 nise along with the possession of movement the 

 presence of other phenomena which are equally 

 characteristic of life and with which non-living 

 material is not endowed? Prominent among the 

 characteristic phenomena of life are the processes ot 

 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 pro- 

 cesses occur characteristically in situations which no 

 one would think of associating with the presence of 

 life. \ 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 preciselv that which is 

 constantly found in living matter.' 



Cliemical Phenomena accompanying Life. 

 It is not so long ago that the chemistry of organic 

 matter was thought to be entirely different from that 

 of inorganic substances. But the line between in- 

 organic and organic chemistry, which up to the middle 

 of the last century appeared sharp, subsequently 



4 G. F. Fitzgerald (Brit- Assoc. Reports. 1898, and Sclent- Trans- Roy 

 Dublin Society, i8q8) arrived at this conclusion with regard to muscle from 

 purely physical considerations. 



5 *' vital spontaneity, so readily accepted by persons ignorant of biology, 

 is disproved by the whole history of science. Every vital manifestntion is a 

 response to a stimulus. .1 provoked phenomenon. It is unnecessary to say 

 this is also the case with brute bodies, since that is precisely the foundation 

 of the great principle of the inertia of matter. It is plain that it is also as 

 applicable to living as to inanimate matter." — Dastre, o/i, c//. , p- 280 



*• '1 he terms "assimilation" and "disassimilation" express the physical 

 and chemical changes which occur within protoplasm as the result of the 

 intake of nutrient material from the circumambient medium and its ultimate 

 transformation ints waste products which are passed out again into that 

 medium ; the whole cycle of these changes being embraced under the term 

 " metabolism." 



" Leduc ("The Mechanism of Life," English translation by W. Deane 

 Butcher, igit) has given many illustrations of this statement. In the 

 Report of the meeting of 1S67 in Dundee is a paper by Dr. J. D Heatoii 

 (On Simulations of Vegetable Growths by Mineral Substances) dealing with 

 the same class of phenomena. The conditions of osmosis 10 cells h.ave been 

 e<i>ecially studied by Hamburger (" Osmotischer Druck und lonenlehre, " 

 (Wiesbaden, 1902-4). 



