ii 4 TEXT-BOOK OF PHYSIOLOGY. 



the equilibrium of its molecules, a liberation of energy, and, in consequence, 

 a transmission outward of impulses through the efferent nerve to muscle, 

 gland, or blood-vessel, separately or collectively, with the production of 

 muscle contraction, a secretion, vascular dilatation or contraction, etc. 

 The reflex actions take place, for the most part, through the spinal cord and 

 medulla oblongata, which, by virtue of their contained centers, coordinate 

 the various organs and tissues concerned in the performance of the organic 

 functions. The movements of mastication; the secretion of saliva; the 

 muscle, gland, and vascular phenomena of gastric and intestinal digestion; 

 the vascular and respiratory movements; the mechanism of micturition, 

 etc., are illustrations of reflex activity. 



