Chap, ii.] OF THE PROCESSES OF ORGANIC CALORIFICATION. 463 



force result from these reactions. There has even been an 

 attempt to prove that the quantity of l&ctic acid produced was 

 proportional to the muscular labour accomplished, and to the 

 temperature developed (Heidenbain). Oxygen is besides indis- 

 pensable to conti-aotion, and to the reparation of the muscular 

 forces.^ In eSect, repose alone does not suffice to restore 

 muscular energy; it is necessary, in order to reconstitute the 

 contractile force, that an oxygenised reparatory liquid should 

 circulate through the muscle. In the living body it is the 

 arterial blood which performs this office. "We can, however, in a 

 certain degree, substitute for the blood in an isolated muscle the 

 injection of a solution largely composed of oxygen, for example, 

 a solution of permanganate of potash. 



If muscular contraction produces heat, inversely heat provokes 

 contractions ; it is a peculiar case of the great law of transforma- 

 tion of physical forces, of which we shall shortly speak. The 

 beatings of the heart are accelerated when hot water is iajected 

 into a vein, even when the temperature of the blood is very little 

 raised thereby. Inversely, imder the slowly graduated influence 

 of cold, the intestines and the hearc contract with less and less 

 energy, then finally stop. This is one of the causes of the 

 hibernal sleep. 



The chemical phenomena which produce organic calorification 

 are accomplished, on the one hand, in the sanguineous and lym- 

 phatic plasmas, since these liquids are living ; on the other, in the 

 tissues, in the anatomical elements themselves, the nutrition of 

 which is moreover closely connected with the quantity and quality 

 of the blood which circulates in the capillaries. We must, then, 

 now briefly describe the physiological mechanism which regulates 

 the local sanguineous circulation, the consumption of the san- 

 guineous aliment, and. consequently, the production of organic 

 heat. 



The regulating agent of the local capillary circulations is the 

 nervous vaso-motory network, the large sympathetic nerve. After 

 1 Heimann, EUrmnts de Ph/yaiologie, p. 231. 



