OP VITAL ACTIONS IN GENERAL. 25 



Plants derive these elements. On the other hand, the Animal, making 

 use of the ternary and quaternary compounds which have been elabo- 

 rated by Plants, is continually restoring their elements to the Inorganic 

 world, in the very forms which they originally possessed; for, as we 

 shall hereafter see, the excretion of Water, Carbonic acid, and Ammo- 

 nia is constantly taking place in the Animal body during life, as_the 

 result of those changes in which its peculiar activity consists. And 

 thus is sustained that balance between Animal and Vegetable nutrition, 

 which is found to be the more wonderful and complete, the more care- 

 fully it is scrutinized. 



2. Distinctive Characters of Vital Actions. 



16. We are now arrived at the second head of our inquiry, namely, 

 the nature of those actions, which distinguish living beings from masses 

 of inert matter, and which are designated as Vital, to mark their dis- 

 tinctness from Physical and Chemical phenomena. There can be no 

 doubt whatever, that, of the many changes which take place during the 

 life, or state of vital activity, of an Organized being, and which inter- 

 vene between its first development and its final decay, a large propor- 

 tion are effected by the direct agency of those forces, which operate in 

 the Inorganic world ; and there is no necessity whatever for the suppo- 

 sition, that these forces have any other operation in the living body, 

 than they would have out of it under similar circumstances. Thus the 

 propulsion of the blood by the heart through the large vessels, is a phe- 

 nomenon precisely analogous to the propulsion of any other liquid 

 through a system of pipes by means of a forcing pump ; and if the ar- 

 rangement of the tubes, the elasticity of their walls, the contractile 

 power of the heart, and the physical properties of the fluid, could be 

 precisely imitated, the artificial apparatus would give us an exact repre- 

 sentation of the actions of the real one. The motor force of the muscles 

 upon the bones, again, operates in a mode that might be precisely repre- 

 sented by an arrangement of cords and levers ; the peculiarity here, as 

 in the former case, being solely in the mode in which the force is first 

 generated. So, again, the digestive operations which take place in the 

 stomach are capable of being closely imitated in the laboratory of the 

 chemist ; when the same solvent fluid is employed, and the same agencies 

 of heat, motion, &c., are brought into play. Moreover we shall here- 

 after see reason to believe, that the peculiar form of Capillary Attrac- 

 tion, to which the term "endosmose" is applied, performs an important 

 part in the changes which are continually taking place in the living body. 



17. But after every possible allowance has been made for the opera- 

 tion of Physical and Chemical forces, in the living Organism, there still 

 remain a large number of phenomena, which cannot be in the least ex- 

 plained by them, and which we can only investigate with success, when 

 we regard them as resulting from the agency of forces as distinct from 

 those of Physics and Chemistry, as they are from each other. It is to 

 these phenomena that we give the name of Vital; the forces from 

 whose operation we assume them to result, are termed vital forces ; and 

 the properties, which we must attribute to the substances manifesting 



