366 THE LAWS OF ORGANIC 



nomena appear as wonderful as the latter. Both 

 objects are material, but composed of different 

 principles ; but whether the difference consist in 

 the simple or compound nature of these, I shall 

 not presume to say. 



CCCCXL. Why the particles of inert mat- 

 ter are attracted to each other, and form a nu- 

 cleus, is unknown ; and we are equally ignorant 

 of the cause that induces particles derived from 

 animal or vegetable matter to combine in order 

 to develope the various parts of either of these 

 great systems of nature. Blood-vessels are ob- 

 served in the foetal germ, before any other or- 

 ganized structure, and, when these are but par- 

 tially formed, they are prepared to promote still 

 further the objects which nature has in view, as 

 they convey and distribute the maternal blood, 

 which is the exclusive source of every subsequent 

 development. As these vessels become more 

 manifest, the progress of organization proceeds, 

 not precisely as an effect of the first exciting 

 impulse, but as an immediate consequence of the 

 progressive evolution of additional structures, 

 and of the more copious supply of maternal 

 blood ; and these causes augment and continue 

 to operate, till the different organs are constitut- 

 ed, which are necessary to maintain an indepen- 

 dent organic and animal life. 



CCCCXLI. It is extremely difficult to de- 

 fine life. If it be supposed to have any indis- 



