22 DISTINCTIVE CHARACTERS OP LIVING ORGANISMS. 



gelatine can only be formed in the animal body by a meta- 

 morphosis of the albumen which it derives from the Plant. 

 The peculiar mode in which the elements of these substances 

 are held together, renders them very prone to decomposition ; 

 so that Organized bodies, when no longer alive, rapidly pass 

 into decay, unless they are secluded from the contact of 

 oxygen, or are kept at a very low temperature. Such decay, 

 however, is continually taking place during life, and would 

 make itself obvious if its products were not carried out of 

 the system as fast as they are generated within it. It 

 essentially consists in the resolution of the four principal 

 components of organic compounds carbon, hydrogen, oxy- 

 gen, and nitrogen, in combination with oxygen drawn from 

 the atmosphere into the three binary compounds, water, 

 carbonic acid, and ammonia, which thus restore to the In- 

 organic world the original materials of Organized fabrics, in 

 the very forms from which those materials were first derived 

 by the agency of the growing Plant. (See VEGET. PHYSIOL.) 

 5. It is, however, by their peculiar actions, that living 

 Organisms are most completely differentiated from the inert 

 bodies of which the Mineral kingdom is composed. There 

 can be no doubt that of many of the changes which take 

 place during the life of an Organized being, a large proportion 

 (especially in the Animal kingdom) are effected by the direct 

 agency of physical and chemical forces ; and there is no 

 reason to believe 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 purely mechanical 

 phenomenon ; as is also the movement of the limbs by the 

 lever-action of the forces brought to bear on their bones. 

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

 stomach are of a purely chemical nature ; and the interchange 

 of gases between the air and the blood, which takes place in 

 the act of respiration, must be regarded in the same light. 

 But after every possible allowance has been made for the 

 operation of physical and chemical forces in the living or- 

 ganism, there still remain a large number of phenomena 

 which cannot be in the least explained by them, and which 

 must be regarded as the result of an agency that differs from 

 these as they differ from each other ; and this agency, which 



