ECOXOMY OF NUTRITIVE MATTER. 57 



ephemeral existence within the ample regions of 

 every drop. Yet even these are still qualified to 

 fulfil other objects in a more distant and far wider 

 sphere; for, borne along, in the course of time, by 

 the rivers into which they pass, they are at length 

 conveyed into the sea, the great receptacle of all 

 the particles that are detached from the objects on 

 land. Here also they float not uselessly in the 

 vast abyss ; but contribute to maintain in exis- 

 tence incalculable hosts of animal beings, which 

 people every portion of the wide expanse of ocean, 

 and which rise in regular gradation from the mi- 

 croscopic monad, and scarcely visible medusa,* 

 through endless tribes of mollusca and of fishes, up 

 to the huge Leviathan of the deep. 



Even those portions of organic matter, which, in 

 the course of decomposition, escape in the form of 

 gases, and are widely diff'used through the atmo- 

 sphere, are not wholly lost for the uses of living 

 nature ; for, in course of time, they also, as we have 

 seen, re-enter into the vegetable system, resuming 

 the solid form, and reappearing as organic pro- 

 ducts, destined again to run through the same 

 never-ending cycle of vicissitudes and transmuta- 

 tions. 



The diffiision of animals over wide regions of 

 the globe is a consequence of the necessity which 

 prompts them to search for subsistence wherever 



* The immensity of the numbers of these animalcules, which 

 people every region of the ocean, may be judged of from the phe- 

 nomenon of the phosphorescent light which is so frequently exhi- 

 bited by the sea, when agitated, and which, as I have already 

 observed, is found to arise from the presence of an incalculable 

 multitude of these minute animals. 



