ANIMAL MOTION. 27 



external temperature that these effects are produced ; they are 

 equally observed when the animal heat varies in its produc- 

 tion. The heating 1 of the organism which accompanies 

 muscular activity, or which results from taking very hot 

 drinks, produces the acceleration in the superficial circulation, 

 which throws out this excess of heat to the surface. Inanition, 

 muscular repose, the drinking of iced waters, &c., slacken the 

 circulation near the surface and check its cooling action. 



Such are, as far as we can explain them in a short chapter, 

 the origin and the distribution of heat in the animal organism. 

 The part played by the circulation of the blood in the distri- 

 bution of heat, perhaps demands more ample details ; and, 

 indeed, we have treated it more fully elsewhere.* In the 

 present chapter we have studied heat only as manifestation of 

 force, and have merely designed to show that, notwithstanding 

 all appearances, heat is of the same nature in the inorganic 

 world and in organised beings. 



CHAPTER IV. 



ANIMAL MOTION. 



Motion is the most apparent characteristic of life ; it acts on solids, 

 liquids, and gases Distinction between the motions of organic and 

 animal life We shall treat of animal motion only Structure of the 

 muscles Undulating appearance of the still living fibre Muscular 

 wave Concussion and myography Multiplicity of acts of contrac- 

 tion Intensity of contraction in its relations to the frequency of 

 muscular shocks Characteristics of fibre at dillerent points of the 

 body. 



MOTION is the most apparent of the characteristics of life ; 

 it manifests itself in all the functions ; it is even the essence of 

 several of them. It would occupy much space to explain the 



* Physiologic medicalc de la. Circulation die Sang. Paris, 18G3 ; and 

 Theorie physiologique dit ClwUra, Gazette Hcbdomadaire de Medecine. 

 1867. 



