100-(70') PHYSIOLOGICAL SIGNIFICANCE OF VITAL FORCE. 



Organic forms do not generate energy, they simply 

 transform or evolve it from that which has been supplied 

 from the outer world. Heat in the body results from 

 combustion the samp as in a furnace. 



Contractility is a special function of muscular tis- 

 sue and is independent of nerve force. This attribute 

 exists in the tissue for a time after death, lasting longer 

 in cold blooded than in warm blooded animals, because 

 of the slowness of the process of the destructive assimi- 

 lation of the tissues. Longet demonstrated that contrac- 

 tility is closely related to the supply of arterial blood 

 in the capillary vessels, for. on diminishing the supply, 

 contractility was lessened, and the temperature of the 

 muscles reduced ; while Matteucci proved that increased 

 heat accompanies muscular contraction. The heat pro- 

 duced by muscular contraction, is divided into two com- 

 plimentary portions, one part appearing as sensible heat, 

 and the other part being converted into mechanical work. 



It matters not whence comes the heat. Avhether from 

 the chemical transformations which take place in the 

 body, or from the sun-force which has for ages lain lock- 

 ed in the coal strata of the earth, when liberated or made 

 dynamic, it represents a detinite 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 secon- 

 dary 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 re- 

 sult of its metamorphosis. 



Prom 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 per- 

 mit the conclusion that nerve force is transformed into 

 motion, heat, light and electricity, it does not yet author- 

 ize the assertion that these can be reconverted into nerve 

 force. 



This correlation doubtless extends to the higher mani- 

 festations of nerve energy, feeling and thought, for 

 their exercise causes disintegration of nerve tissue, as 



