MOTION IN THE ANIMAL ORGANISM. 



65 



of these manifestations are confined within ; 

 certain limits. 



We observe in animals, that the conver- 

 sion of food into blood, and the contact of 

 the blood with the living tissues, are deter- 

 mined by a mechanical force, whose mani- 

 festation proceeds from distinct organs, and 

 is effected by a distinct system of organs, 

 possessing the property of communicating 

 and extending the motion which they re- 

 ceive. We find the power of the animal to 

 change its place and to produce mechanical 

 effects by means of its limbs, dependent on 

 a second similar system of organs or appa- 

 ratus. Both of these systems of apparatus, 

 as well as the phenomena of motion pro- 

 ceeding from them, are wanting in plants. 



In order to form a clear conception of the 

 origin and source of the mechanical mo- 

 tions in the animal body, it may be advan- 

 tageous to reflect on the modus operand! of 

 other forces, which in their manifestations 

 are most closely allied to the vital force. 



When a number of plates of zinc and 

 copper, arranged in a certain order, are 

 brought into contact with an acid, and when 

 the extremities of the apparatus are joined 

 by means of a metallic wire, a chemical ac- 

 tion begins at the surface of the plates of 

 zinc, and the wire, in consequence of this 

 action, acquires the most singular and won- 

 derful properties. 



The wire appears as the carrier or con- 

 ductor of a force, which may be conducted 

 and communicated through it in every di- 

 rection with amazing velocity. It is the 

 conductor or propagator of an uninterrupted 

 series of manifestations of activity. 



Such a propagation of motion is incon- 

 ceivable, if in the wire there were a resist- 

 ance to be overcome ; for every resistance 

 would convert a part of the moving force 

 into a force at rest. 



When the wire is divided in the middle, 

 and its continuity interrupted, the propaga- 

 tion of force ceases, and we observe, that in 

 this case the action between the zinc and 

 the acid is immediately stopped. 



If the communication be restored, the ac- 

 tion which had disappeared reappears with 

 all its original energy. 



By means of the force present in the 

 wire, we can produce the most varied ef- 

 fects ; we can overcome all kinds of resist- 

 ance, raise weights, set ships in motion, &c. 

 And, what is still more remarkable, the 

 wire acts as a hollow tube, in which a cur- 

 rent of chemical force circulates freely and 

 without hindrance. 



Those properties which, when firmly at- 

 tached to certain bodies, we call the strongest 

 and most energetic affinities, we find, to all 

 appearance, free and uncombined in the 

 \vire. We can transport them from the 

 wire to other bodies, and thereby give to 

 them an affinity (a power of entering into 

 combination) which in themselves they do | 

 not possess. According to the amount of j 

 force circulating in the wire, we are able by I 



means of it to decompose compounds, the 

 elements of which have the strongest at- 

 traction for each other. Yet the substance 

 of the wire takes not the smallest share in 

 all these manifestations of force ; it is 

 merely the conductor of force. 



We observe, further, in this wire, phe- 

 nomena of attraction and repulsion, which 

 we must ascribe to the disturbance of the 

 equilibrium in the electric or magnetic 

 force ; and when this equilibrium is restored, 

 the restoration is accompanied by the de- 

 velopement of light and heat, its never-fail- 

 ing companions. 



All these remarkable phenomena are pro- 

 duced by the chemical action which the 

 zinc and the acid exert on each other ; they 

 are accompanied by a change in form and 

 structure, which both undergo. 



The acid loses its chemical character ; the 

 zinc enters into combination with it. The 

 manifestations of force produced in the wire 

 are the immediate consequence of the 

 change in the properties of the acid and the 

 metal. 



One particle of acid after another loses its 

 peculiar chemical character; and we per- 

 ceive that in the same proportion the wire 

 acquires a chemical, mechanical, galvanic, 

 or magnetic force, whatever name be given 

 to it. According to the number of acid 

 particles which in a given time undergo 

 this change, that is, according to the sur- 

 face of the zinc, the wire receives a greater 

 or less amount of these forces. 



The continuance of the current of force 

 depends on the duration of the chemical ac- 

 tion ; and the duration of the latter is most 

 closely connected with the carrying away, 

 by conduction, of the fdVce. 



If we check the propagation of the cur- 

 rent of force, the acid retains its chemical 

 character. If we employ it to overcome 

 chemical or mechanical resistance, to de 

 compose chemical compounds, or to pro- 

 duce motion, the chemical action continues j 

 that is to say, one particle of acid after 

 another changes its properties. 



In the preceding paragraphs we have 

 considered these remarkable phenomena in 

 a form which is independent of the explana- 

 tions of the schools. Is the force which 

 circulates in the wire the electrical force? 

 Is it chemical affinity? Is it propagated in 

 the conductor like a fluid set in motion, or 

 in the form of a series of momenta of mo- 

 tion, like light and sound, from one particle 

 of the conductor to another ? All this we 

 know not, and we shall never know. All 

 the suppositions which may be employed 

 as explanations of the phenomena have not 

 the slightest influence on the truth of these 

 phenomena; for they refer merely to the 

 form in which they are manifested. 



On some points, however, there is no 

 doubt; namely, that all the effects which 

 may be produced by the wire are deter- 

 mined by the change of properties in the 

 zinc and in the acid ; for the term " chemi- 



