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 appearing as sensible heat, and the other part being converted into mechanical 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 mechanical 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 metamorphosis.
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 disintegration of nerve-tissue, as shown by the excreted products of decomposition 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 expressed 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 overthrown the vitalistic doctrines of the past, and demonstrated by analysis 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 synthesis, by combining these same molecules and restoring these same forces, should be able to reproduce the forms and functions of life.