AND ANIMAL LIFE. 207 



frequent renewal of this fluid from the excited ac- 

 tion of the capillaries. 



If a given quantity of blood be transmitted to 

 any part of the external surface of the body, the 

 region in which it is distributed will feel warm ; 

 and if this quantity be doubled, without in the 

 least affecting its temperature, the sensation of 

 heat will be proportionally augmented, because 

 a greater number of points, which communicate the 

 sensation, is contained within a given space. If 

 the blood which circulates on the surface of the 

 body be renewed more frequently than natural, 

 the part thus circumstanced will be warmer. The 

 blood on the surface is seldom or never so warm 

 as that which belongs to the cavities ; its tempe- 

 rature is diminished from the influence of an ex- 

 ternal medium, to which the internal circulation 

 is not at all exposed ; but when the vital fluid 

 returns to the surfece in one half of its usual 

 time, the causes which tend to lessen its heat 

 produce less decided effects, from its increased 

 velocity, or diminished sojourn in the capillaries. 



