Uct. 25, I888J 



NATURE 



627 



(7.Y THE O RIG IX AND THE CAUSATION OF 

 VITAL MOVEMENT} 



I. 



\ M< fNG the phenomena of life the movement of masses, or 

 *"*■ mechanical work, takes a prominent place. It is the most 



lie of all the vital processes; to OUT sensual perceptions, so 

 universally distributed, and so hound up with most of the 

 activities of organisms that it might almost be designated the 

 incarnation of life. 



In saying tbis it must be understood that vital movement is 

 by no means exclusively confined to animals— that it is not, as 

 was once believed, a special animal function ; on the contrary, 

 it is an attribute of all living matter, as well of the lowest 

 creatures as of the most highly developed plants, so that, how- 

 ever extraordinary it may appear, the activity of our muscles 

 which enables us to transform sensation into action finds an 

 analogue in the plant. Our conviction of the inter-connection 

 and profound unity of all living things has thus a physiological 

 foundation, based as it is not merely on the community of deriva- 

 tion and of structure of living things, but also on the proof of 

 .similar activities. 



If a division of the morphological from the physiological is in 

 any way permissible, it may be said that the unitary conception 

 of life for which our age is distinguished rests in a higher degree 

 on the knowledge of vital processes than is commonly recognized, 

 and in fact is just as much founded on physi logical experience 

 as on that of the forms of the organism. 



From the traditional conception of life, which scarcely con- 

 tained more than that everything between life and death is the 

 antithesis of the not living, it is a long road we have had to 

 travel to attain to the modern conception of the real unity of 

 life ; and a remarkable road, since it bears witness to the con- 

 fident anticipation of victory, in face of all impediments raised 

 Up by science it c elf. Movement, and nothing less, had been 

 placed at the summit of that antithesis, which physico-chemical 

 research in the animal and vegetable kingdom had revived with 

 the discovery that the plant transformed kinetic into potential 

 energy, and the animal the latter into the former. While the 

 animal made use of oxygen to generate heat and perform work 

 through ihe metabolism of its substance, the plant made use of 

 the heat in reducing and synthetic processes for the accumulation 

 of potential energy in the form of its own consumable substance 

 and the expired oxygen. 



With wha'ever unassailable correctness this conception com- 

 prehends life as a whole, affording a pleasing solution of its 

 antithesis by referring animal activities to nourishment by the 

 plant, the latter to the products of the combustion of the animal 

 body, and both in the last instance to the forces of the sun as 

 original source of all life, yet th'-s did but cast up the sum-total 

 of the processes of life, and did but express more intimately 

 than befove that which divides the most highly-developed 

 branches of the animal and vegetable kingdom, in which the 

 divergence of forms and arrangements is greatest. For by the 

 side of this distinction there exists even between man and the 

 most highly elaborated plant a connection of a kind quite other 

 than the symbiotic interdependence through the medium of light, 

 air, and food, a community, however, which is not disclosed 

 until we go back to the ultimate elements of organization. 



As in the animal synthetic processes are not wanting, without 

 which it could not even produce a molecule of the colouring 

 matter of its blood, so in the plant we are acquainted with dis- 

 sociations and combustion, and also with evolution of heat and 

 movement of masses ; not that by this I refer to those coarser 

 movements which are referable to turgescence, but primitive 

 movements, which we find first in the smallest elementary 

 organisms, of whic' 1 . all living beings are made up. 



We have almost in our own persons lived to see the old antici- 

 pation <>f a single kingdom of living things become gradually an 

 established truth through the discovery of the cell. After the 

 ground-lines of the construction of plants and animals out of 

 originally similar nue'eated cells had been established by 1h. 

 Schwann, and since Darwin's immortal work enabled us to 

 derive everything that ever lived or will live from one single 

 cell, we have come to realize that every single organism renews in 

 itself the work of past ages, and again builds itself up from a 



« "On the Origin and the Causation of Vital Movement {I'tbcr die Ent- 

 ttthumg der vitalen Beweguug)" being the Crooninn Lecture del vered 111 

 the Theatre . f the Royal 'institution on May 28, c3S8, by Dr. \V. (Cflhne, 

 Pr. fts: or of Physiology in ihe University of Heidelberg. 



germ similar to that from which its most ancient ance-: 

 s'arted. 



This conviction has become so firmly implanted in our genera- 

 tion 1 hat now we scarcely feel the gaps which still exist in our 

 actual knowledge, and almost unjustly underestimate that which 

 the investigation! of our contemporaries yet add to the cell- 

 theory, as if it were mere work of repetition. And yet it has 

 been very extensive and decisive- for example, the recent 

 researches upon the intimate structure of the cell-nucleus — since 

 nothing less results from it than that the reproduction of the 

 cell by fission takes place identically, down to the most minute 

 details, in all animals and plants. 1 



Now, if the shaping of the cell and all the fashioning of 

 forms is an actirify, and if Morphology, "since it has made the 

 arising of form more its study than the describing of what is 

 already completed.'' has become part of Physiology, it might be 

 Me and conceivable that research directed to all activities 

 and going beyond the visible form to the chemical components 

 of the structures and the transformation of substance and force, 

 should observe great differences in processes where all our 

 morphological experience would only have shown identity. We 

 were near enough to this point ; for if it were true, as was long 

 assumed, that that which is the bearer and the seat of the most 

 essential of all vital processes in the cell is completely form! 

 it is not easy to see why the form should be so determinant of 

 function. 



We have hope that this is not so, and will endeavour to show 

 in Movement the functional as well as the morphological unity 

 of all living matter. 



As I have already said, there is an elementary kind of move- 

 ment in the cell, carried out by the cell-body — that part of the 

 cell which, in contradistinction to nucleus, membranes, and 

 various inelosures, has been designated protoplasm. The proto- 

 plasm moves itself, as in the case of certain free-living Proto- 

 zoa, like the long-known Amoeba, like the so-called sarcode — 

 in many cases better comparable to the movement of the pseudo- 

 podia of Rhizopods. The resemblance of the latter to what was 

 formerly called the sap-current in many plant-cells, led Ferd. 

 Cohn 2 to interpret plant protoplasm as sarcode, an idea actively 

 supported by Max Schultze, 3 the best authority on pseudopxlial 

 movement. It is not necessary to say here how widespread 

 protoplasmic movement is, for there cannot be a cell that does 

 not present it at some stage of its existence. Doubt on this 

 subject can only exist in regard to the smallest of all organisms, 

 those of fermentation, of putrefaction, and of pathogenic activity 

 which are too small for observation. But even in these, from 

 the movement they perform as a whole, we have grounds to 

 infer the existence of a protoplasm. 



It is proved that protoplasmic movement does not follow 

 external impulses or currents, but is a spontaneous activity. It 

 may go on in opposition to gravity, and overcomes frictional 

 resistance, as shown by the mass itself moving forward on 

 surfaces of every kind, and being able to drag heavy bodies 

 along with it. It is proper mechanical work. 



The cause of the movement can only be an internal one, 

 residing in the contractile substance itself, and can only consist 

 of chemical processes taking place within the peculiar pasty, 

 slime-like mass. Yet the question had to be put whether these 

 processes were not first set up by something coming perhaps 

 from the outside, for the movement changes, sometimes stops 

 or takes place more slowly, or occurs but partially, and may by 

 many means be artificially aroused or diminished. 



At this point experimental phy-iological research had to step 

 in, attacking the problem in the same way as it had long before 

 done in the case of the most highly-developed contractile struc- 

 tures, the muscles. A muscle behaves so far just like proto- 

 plasm that its contracion does work, which can only depend on 

 chemical transformations of its own substance, during which 

 potential is converted into kinetic energy ; but it differs in that 

 a distinct impulse from without is needed to set the game going. 

 In normal conditions it receives the initiating impulse from its 

 nerve, and nothing else appears able to take its place, since 

 nothing that might otherwise act upon it, such as the motion of 

 1 1 he m ist implete exposition <if the-;e important later discoveries on the 

 reproducti n of the cell is to tic found in the bwk of YV. Hemming, " Zell- 

 pubBtant. Kern und ZelllheUung," Leipzig, t88a C/. the " (Curzehut nsche 

 Uebersicht" (p 385), with the ijuo-ations from the works of Schneider, 

 Strassburgcr, Btttschll, Hemming, O. Hertwig, and the research 

 Auerbach, lialhiani. van IWnedea. Eberth. Schleicher, Balfour, and othrs. 

 ichtrage zj»r Naturgeschichto des Protoc ecus pluviatilis," Xova 

 [eta Acad. Leopold Ctetar., vo'. audi. Part 2, p. 60= (1850). 

 3 •' Ueber den Organismusder Polythalamien," Leipzig, 1854. 



