348 ANIMAL NATURE AS A WHOLE. [in. 



683. The natural subordination of excretion and secretion 

 to the two primary vital forces is less direct, because they 

 imply the action of the arteries, for the latter must carry 

 those materies, the external impressions of which excite them 

 to the functions of secretion and excretion, and subserve 

 thereto (472). 



684. The movements of muscular fibrils, of membranes, of 

 muscles, and of muscular viscera and organs (162), are also 

 subordinate to the two primary vital forces. The influence 

 both of the vital spirits and of the blood is necessary to the 

 natural actions of all these. Although the subordination is 

 more direct than in the glandular system and excretory viscera, 

 co-ordinate forces are required, inasmuch as all muscular action 

 requires also an internal or external impression (162, 448). 



685. The function of respiration in breathing animals, 

 being effected by muscular tissue, follows the law of subordina- 

 tion of muscular action in general. 



686. Lastly, all compound functions of the viscera are 

 subordinate to the primary vital forces, in accordance with the 

 preceding laws. The functions of the sexual organs, whether 

 male or female, — as copulation, &c., include those of arteries, 

 capillaries, muscles, glands, &c., and are subordinate, according 

 to the age and conditions of the constituent parts. 



687. But even these compound animal functions, as respira- 

 tion, digestion, generation, have a number of functions subor- 

 dinate to them, inasmuch as their effects extend through the 

 entire animal economy. This is very remarkably the case 

 with the function of generation, which, in those which have 

 sexual congress (633), puts animal forces into operation that 

 are subordinate to it in a wonderful manner. 



688. The diaphragm and the stomach (which forms with 

 the intestines one canal) stand in very close relation to each 

 other, and attentive observers have recognised the region in 

 which they are situate, as a very general centre of animal forces ; 

 not only because many nerves meet and communicate there, 

 but because many phenomena prove it to be such. Violent 

 injury of this region causes great general changes in the body, 

 and diseases of these parts derange many animal functions. 

 Thus, worms and mucus in the stomach excite convulsions of 

 the extremities ; colic induces paralysis ; bad digestion causes 



