41O PROPAGATION OF THE SPECIES. CHAP. IX. 



parum and Poa alpina; and as plants of this kind 

 are mostly alpine, it has been thought to be an in- 

 stitution or resource of nature to secure the propa- 

 gation of the species in situations where the seed 

 may fail to ripen. 



The bud. The bud though it does not spontaneously de- 

 tach itself from the plant and form a new individual, 

 will yet sometimes strike root and develope its 

 parts if carefully separated by art and planted in 

 the earth : but this is to be understood of the leaf- 

 bud only, for the flower-bud if so treated always 

 perishes.* 



But the species may sometimes be propagated 

 even by means of the leaves ; as is, I believe, the 

 case with the leaves of the Orange 3 Aloe, Sea-onion, 

 and some species of Arum, which if carefully de- 

 posited in the soil will grow up into new plants, by 

 virtue, no doubt, of some latent gem contained in 

 them ; in which case, as well as in all of the preced- 

 ing cases, the propagation of the species is obviously 

 effected by means of a principle different from the 

 seed, which botanists generally designate by the ap- 

 pellation of the gem. 



The pro- But this is not so obviously true in the case of 

 gongylus. the Propago and Gongylus the simple gems of 

 Gaertner ; because it has been contended that they 

 are still but seeds. Gaertner, however> excludes 

 them entirely from the rank of seeds upon the fore- 

 going grounds, and maintains, in opposition to the 

 * Mirbel Phys. Veg. vol. i. p. 220. 



