2 NATURE OF LIVING BODIES. 



Plants, on-the contrary, are undergoing constant and sponta- 

 neous chances; some are dying and decaying, whilst others 

 are \spffluting up frbrii 'the earth, coming forth, as it were, 

 from a new creation, giving birth to a new set of individuals 

 like themselves, and sinking in their turn to decay. Further 

 still, we see animals, not only coming into existence, living, 

 growing, and giving origin to other animals, but exercising 

 various other offices; feeling, moving, uttering sounds, suf- 

 fering and enjoying, establishing a thousand connections with 

 things and beings about them, which contribute to the sup- 

 port or happiness of their existence. In this way we have 

 come to the division of created things into the three classes 

 above mentioned." It is sufficient and convenient for the pop- 

 ular purposes to which it has been usually applied, but it is 

 evident, if we but examine it,\that it is not strictly and scien- 

 tifically correct. 



A more accurate and philosophical division of natural ob- 

 jects is into Such as are possessed of life, and such as are not 

 possessed of life. This throws animals and vegetables into 

 one class, and all mineral substances into the other ; for there 

 is a much more close and intimate relation between the two 

 former, than there is between either of them and the latter. 

 They have many circumstances of analogy with one another, 

 in respect to their structure and functions, in which they do 

 not at all resemble any objector operation of the mineral king- 

 dom. These two classes, then, include all the various bodies 

 winch compose the world around us, and those belonging to 

 each are distinguished as possessing certain general proper- 

 ties, and being governed by certain general laws, common, in 

 a greater or less degree, to all of the same class. 

 ^ In the first place, living bodies are distinguished from other 

 substances in the mode of their origin ; they are always pro- 

 duced by other preceding individuals similar to themselves ; 

 they are always the offspring of parents. This is an obvious 

 and complete distinction. No mineral substance, no sub- 

 stance not possessed of life, is ever brought into existence in 

 this way. It is true, that new bodies in the mineral world 

 are sometimes formed by the accidental aggregation of par- 

 ticles, or by the spontaneous combinations which are occa- 

 sionally the result of chemical laws ; but this is clearly some- 

 thing very different from the mode of production which takes 

 place in living bodies. One stone does not produce another 

 like itself; a crjstal does not produce a crystal, nor one grain 

 of sand another. There is nothing like the relation of parent 

 and offspring. 



