470 CHARACTER OF VEGETABLE VITALITY. CHAP. XI. 



table nature, and affording the only incontrovertible 

 test by which the plant is to be discriminated from 

 the animal ; namely, that the reproductive organs 

 after having discharged their peculiar functions, 

 uniformly decay and drop off before the fruit has 

 reached maturity, while those of the animal remain 

 permanent, and perish only with the individual 

 itself.* But if it is true, as Gaertner maintains, 

 that some genera, perhaps even some tribes of 

 plants are destitute of sexual organs altogether, and 

 propagated not by seeds but by gems ; or if there 

 are either plants or animals whose sexual organs 

 have not yet been detected, as in the case of the 

 Polypi, what after all is the value of the rule ? 

 OfMirbel. Finally, M. Mirbel, a botanist of some consider- 

 able celebrity on the continent, has introduced a 

 criterion founded on the character of the substances 

 on which plants and animals respectively feed. 

 Plants feed upon unorganized substances, that is, 

 upon earths, salts, water, or gases : animals feed 

 upon substances already organized, that is either 

 upon vegetables, or animals, or their products ; but 

 never wholly upon substances in an unorganized 

 state. Such is obviously the fact, at least in the 

 case of the more perfect animals and vegetables, 

 which M. Mirbel was accordingly not the first to 

 remark ; for the remark had been made, essentially 

 at least, by Lord Bacon, though the division of ma- 

 terial substances into organized and unorganized 

 * Tracts relative to Bot. London, 1805, 



