PHYSIOLOGICAL SIGNIFICANCE OF VITAL FORCE. 769 



diminishing the supply, contractility was lessened, and the temperature 

 of the muscles reduced ; while Matteucci proved that increased heat 

 accompanies muscular contraction. The heat produced by muscular 

 contraction is divided into two complementary portions, one part ap- 

 pearing as sensible heat, and the other part being converted into me- 

 chanical work. 



It matters not whence comes the heat, whether from the chemical 

 transformations which take place in the body, or from the sun-force 

 which has for ages lain locked in the coal-strata of the earth, when 

 liberated or made dynamic, it represents a definite amount of mechani- 

 cal power. 



Nerve-energy is transformed into motion, as evidenced in muscular 

 action ; it is also transformed into heat, but it is not known whether 

 it is an immediate or a secondary result. There are some instances 

 recorded which seem to show its transformation into light, and it is 

 well known that in certain animals electricity is the direct result of its 

 metamorph osis. 



From these data the conclusion seems authorized that at least a 

 partial correlation exists between the physical forces and the energy 

 resulting from nerve-action. I say a partial correlation, because, while 

 the evidence may permit the conclusion that nerve-force is transformed 

 into motion, heat, light, and electricity, it does not yet authorize the 

 assertion that these can be reconverted into nerve-force. 



This correlation doubtless extends to the higher manifestations of 

 nerve-energy, feeling, and thought, for their exercise causes disin- 

 tegration of nerve-tissue, as shown by the excreted products of decom- 

 position and increased muscular action, as evidenced in the increased 

 circulation of the blood. Physical conditions, therefore, determine 

 mental results. The higher nerve-tissue of the brain operates under 

 physical and chemical conditions in its nutrition, the same as does the 

 tissue of any other organ, and hence its transformed energy, as ex- 

 pressed in nervous or mental action, has its physiological representation 

 and measurable force. 



To extend this subject further in the line of analysis, though it 

 might be interesting, is unnecessary for the object proposed, which is 

 to show that chemical, physical, and biological sciences have over- 

 thrown the vitalistic doctrines of the past, and demonstrated by analy- 

 sis a relationship between the forces which rule the inorganic world 

 and the " vital force " which is manifested in living forms. At this 

 point the question is properly asked, if chemical synthesis confirms the 

 results and conclusions of chemical analysis. 



If the morphology and physiology of organisms are the products 

 simply of physical molecules under chemical and physical forces which 

 are revealed by analysis, then the assumption seems justified that syn- 

 thesis, by combining these same molecules and restoring these same 

 forces, should be able to reproduce the forms and functions of life. 

 VOL. xxiT. — 49 



