CHEMICAL AND MECHANICAL STIMULATION 163 



CHEMICAL AND MECHANICAL STIMULATION 



CHEMICAL STIMULATION 



THE contractility, heat production, and other 

 phenomena of the life of muscle rest at base on 

 chemical processes. Anything that sufficiently 

 alters these processes may be a stimulus. A most 

 important source of stimulation is the alteration 

 of the chemical composition of muscle through 

 osmosis. 



Effect of Distilled "Water. Place a sartorius 

 muscle in distilled water. 



Irregular contractions usually occur. The 

 muscle soon swells, and becomes white, turbid, 

 cadaveric. 



These striking changes depend on the with- 

 drawal of certain bodies by osmosis. Muscle 

 contains large quantities of proteid, particularly 

 proteids of the globulin class ; certain carbo- 

 hydrates, such as glycogen ; nitrogenous and 

 other extractives ; water ; and a number of in- 

 organic salts. Most of these bodies are largely 

 or wholly insoluble in water, and require for 

 their solution the presence of inorganic salts. 



