MOTION OF ANIMAL ORGANISM. 



C9 



leeornpose carbonic acid, and to assimilate 

 the elements of its nourishment. 



In the flower alone does a process similar 

 to the change of matter in the animal body 

 occur. There, phenomena of motion ap- 

 pear ; but the mechanical effects are not 

 propagated to a distance, owing to the ab- 

 sence of conductors of force. 



The same vital force which we recognize 

 in the plant as an almost unlimited capacity 

 of growth, is converted in the animal body 

 into moving power (into a current of vital 

 force ;) and a most wonderful and wise eco- 

 nomy has destined for the nourishment of 

 the animal only such compounds as have a 

 composition identical with that of the organs 

 which generate force, that is, with the mus- 

 cular tissue. The expenditure of force 

 which the living parts of animals require, 

 in order to reproduce themselves from the 

 blood ; the resistance of the chemical force 

 which has to be overcome in the azotized 

 constituents of food by the vital agency of 

 the organs destined to convert them into 

 blood ; these are as nothing compared to 

 the force with which the elements of carbo- 

 nic acid are held together. A certain amount 

 of force would necessarily be prevented from 

 assuming the form of moving power, if it 

 were to be expended in overcoming chemical 

 resistance ; for the momentum of motion of 

 the vital force is diminished by all obstacles. 

 But the conversion of the constituents of 

 blood into muscular fibre (into an organ 

 which generates force) is only a change of 

 form. Both have the same composition; 

 blood is fluid, muscular fibre is solid blood. 

 We may even suppose that this change 

 takes place without any expenditure of vital 

 force ; for the mere passage of a fluid body 

 into the solid state requires no manifestation 

 of force, but only the removal of obstacles, 

 which oppose that force (cohesion) which 

 determines the form of matter, in its mani- 

 festations. 



In what form or in what manner the vital 

 force produces mechanical effects in the ani- 

 mal body Is altogether unknown, and is as 

 little to be ascertained by experiment as the 

 connexion of chemical action with the phe- 

 nomena of motion which we can produce 

 with the galvanic battery. AH the explana- 

 tions which have been attempted are only 

 representations of the phenomenon; they 

 are, more or less, exact descriptions and 

 comparisons of known phenomena with 

 these, whose cause is unknown. In this re- 

 spect we are like an ignorant man, to whom 

 the rise and fall of an iron rod in a cylinder, 

 in which the eye can perceive nothing, and 

 its connexion with the turning and motion 

 of a thousand wheels at a distance from the 

 piston-rod, appear incomprehensible. 



We know not how a certain something, in- 

 visible and imponderable in itself (heat) gives 

 to certain bodies the power of exerting an 

 enormous pressure on surrounding objects ; 

 we know not even how this something it- 

 Be] f is produced when we burn wood or coals. 



So is it with the vital force, and with the 

 phenomena exhibited by living bodies. The 

 cause of these phenomena is not chemical 

 force ; it is not electricity, nor magnetism \ 

 it is a force which has certain properties in 

 common with all causes of motion and of 

 hange in form and structure in material 

 substances. It is a peculiar force, because 

 it exhibits manifestations which are found in 

 no other known force. 



II. In the living plant, the intensity of the 

 vital force far exceeds that of the chemical 

 action of oxygen. 



We know, with the utmost certainty, that 

 by the influence of the vital force, oxygen is 

 separated from elements to which it has the 

 strongest affinity ; that it is given out in the 

 gaseous form, without exerting the slightest 

 action on the juices of the plant. 



How powerful, indeed, must the resistance 

 appear which the vital force supplies to 

 leaves charged with oil of turpentine or tan- 

 nic acid, when we consider the affinity of 

 oxygen for these compounds ! 



This intensity of action or of resistance 

 the plant obtains by means of the sun's 

 light ; the effect of which in chemical ac- 

 tions may be, and is, compared to that of a 

 very high temperature (moderate red heat.) 



During the night an opposite process goes 

 on in the plant ; we see then that the con- 

 stituents of the leaves and green parts com- 

 bine with the oxygen of the air, a property 

 which in daylight they did not possess. 



From these facts we can draw no other 

 conclusion but this : that the intensity of the 

 vital force diminishes with the abstraction 

 of light 5 that with the approach of night a 

 state of equilibrium is established, and that 

 in complete darkness all those constituents 

 of plants which, during the day, possessed 

 the power of separating oxygen from chemi- 

 cal combinations; and of resisting its atruon, 

 lose their power completely. 



A precisely similar phenomenon is ob- 

 served in animals. 



The living animal body exhibits its pecu- 

 liar manifestations of vitality only at certain 

 temperatures. When exposed to a certain 

 degree of cold, these vital phenomena en- 

 tirely cease. 



The abstraction of heat must, therefore, 

 be viewed as quite equivalent to a diminu- 

 tion of the vital energy ; the resistance op 

 posed by the vital force to external causes of 

 disturbance must diminish, in certain tempe- 

 ratures, in the same ratio in which the 

 tendency of the elements of the body to 

 combine with the oxygen of the air in- 

 creases. 



By the combination of oxygen with the 

 constituents of the metamorphosed tissues, 

 the temperature necessary to the manifesta- 

 tions of vitality is produced in the carnivora. 

 In the herbivora, again, a certain amount of 

 heat is developed by means of those elements 

 of their non-azotized food which have the 

 property of combining with oxygen. 



It is obvious that the temperature of an 



