16 GENERAL CHARACTERS OF LIVING BEINGS. 



every other part ; it lias the same structure, the same properties. 

 If it possesses the crystalline form, it may be reduced into an 

 almost indefinite number of smaller crystals similar to itself; 

 and as to its properties, the chemist cares not (except as a matteu 

 of convenience) whether he examines a single grain or a mass 

 of a ton weight. Nay, of many substances the properties are 

 so peculiar, that they can be recognised with certainty in quan- 

 tities so minute as to be scarcely visible ; thus, arsenic, when 

 administered as a poison, has been detected after death in a 

 quantity probably less than the hundredth of a grain ; and yet 

 the experienced chemist has no hesitation in asserting that this 

 minute crystalline metallic substance is arsenic, because he recog- 

 nises in it the same form and the same properties, which a larger 

 mass of that substance would exhibit. 



3. Far different is it with regard to a Plant or Animal. 

 These also may be divided and subdivided; but they then 

 entirely lose their original character ; for the parts or organs no 

 longer bear any resemblance to the whole or to each other, either 

 in form, structure, or properties. Thus, then, we see that the 

 bodies which are formed to exhibit those actions to which we 

 give the general term of Life, are peculiarly distinguished from 

 dead matter, by the presence in them of a number of parts or 

 organs > distinct alike in their form, structure, and properties ; 

 hence such are called organised bodies. On the other hand, 

 dead inert matter may be divided, with any degree of minute- 

 ness, into parts similar to each other in form, structure, and 

 properties ; hence it is termed inorganic, or destitute of organs. 



4. There is another peculiarity possessed by living beings, 

 in regard to their actions or functions. Some of these actions are 

 governed by the same laws as those which operate on inorganic 

 matter ; the blood is propelled by the heart of an animal, for 

 example, through its system of branching vessels, just upon the 

 same principle that a forcing-pump drives water through the 

 pipes which convey it over a large city. But the nature of the 

 force is quite different. In the latter case it is merely mechani- 

 cal. In the former it results from a property peculiar to 

 organised structure, and especially manifested in that form of it 



