EVOLUTION AND DISSOLUTION 



nation to final decomposition, its career consists 

 of an epoch of concentration followed by an 

 epoch of diffusion. A very small portion of its 

 constituent matter preexisted in a concentrated 

 form in the embryo ; by far the greater portion 

 preexisted in the shape of dispersed nitroge- 

 nous and carbonaceous compounds, which the 

 growing organism has incorporated with its 

 own structure. Nay, even if we inquire into the 

 previous history of the small portion which was 

 concentrated in the embryo, we may trace it 

 back to an epoch at which it existed in a state 

 of dispersion, as food not yet assimilated by the 

 parent organism. If the organism in question 

 belong to an order of carnivorous animals, we 

 shall indeed have to follow its constituent ele- 

 ments through a series of phases of concentra- 

 tion ; through the tissues of sundry herbivo- 

 rous animals upon which it has fed, and again 

 through the tissues of numerous plants upon 

 which these have in turn subsisted ; but in the 

 end we shall always arrive at the host of dis- 

 persed molecules which these organisms have 

 eliminated from the breezes and the trickling 

 streamlets by which their leaves and roots were 

 formerly bathed. On the other hand, when the 

 animal dies, and the tree falls to decay, the par- 

 ticles of which they consist are again dispersed ; 

 and though they may again be brought together 

 in new combinations, the career of the organism 



vol. n. I 93 



