48 OF VITAL MOTION. 



exaggerate the original expansion, and so give rise to the 

 phenomena of inflammation; but under ordinary cir- 

 cumstances, the " capillary power" is so ruled, that all 

 parts are affected equally, the office being to destroy 

 the contraction of the vessel, which would counteract 

 the action of the heart, and not to determine the flow 

 of blood to one part rather than another. 



The mode of capillary action may indeed be illus- 

 trated by the circumstances which favour the injec- 

 tion of the vessels, which is necessary for anatomical 

 purposes, and the illustration is perfectly legitimate. 

 The fluid, as we know, passes from the syringe into 

 the minutest vessel with great readiness, so long as 

 the animal continues warm, or when the warmth is 

 restored by immersion in the warm bath, but the con- 

 trary is the result when the animal is cold. In the 

 one case the operation succeeds, as it would appear, 

 because the passages present little or no resistance to 

 the force of the syringe in the other it fails, on 

 account of that contracted state which has taken place 

 in the vascular tunics, and in the tissues generally, 

 when the body has become cold. No other explana- 

 tion is admissible than that which refers to physical 

 agents for life has ceased ; nor is any other needed, 

 for all the phenomena may be accounted for by the 

 changes which must take place in the coats of the 

 vessels, under varying degrees of temperature. 



So also, we may argue of the natural circulation, if 



