192 PHYTOTOMY. 



the vessels of Confervae, as also in those which ooze out upon 

 the epidermis of Lichens. These, when they have come to 

 their mature state, are separated from their parent body, and 

 constitute new individuals, which retain not only the essential, 

 but the accidental nature of the parent plants; for it is a leading 

 character of propagation by germs, that these are properly to 

 be regarded as a continuation of the parent plant, by the con- 

 densation of its substance, on which account even accidental 

 peculiarities and diseases propagate themselves in this way, 

 and from this cause the shades of colour in the Lichens and 

 Sponges are so constant, that we are forced to assume them 

 also into the characteristic description. But this very circum- 

 stance renders the determination of species, in these lower or- 

 ganic bodies, a matter of doubt, for propagation by seed is, 

 in their case, out of the question. 



303. 



In trees and woody plants, the structure of the germ is of 

 a more complex nature. The parts of the stem and branches 

 become crowded in particular positions, pass into the sub- 

 stance of each other, and, in this manner, reservoirs and 

 joints are produced, which we observe both in the leaf- 

 stalk of trees of the citron kind, and in the fleshy leaves 

 of other plants. These reservoirs consist of a compact cellu- 

 lar texture, and of the congregated rudiments of new sap- 

 vessels and spiral-vessels, and may be artificially produced, 

 namely, by making an incision in a branch, and thereby pro- 

 moting the appulse of the sap. In every attempt to pro- 

 duce buds artificially, it is a necessary condition of success 

 that these reservoirs should first be formed. They are in- 

 deed produced in all woody plants, even when no proper 

 buds appear, as, in tropical trees especially, we observe them 

 occupying the place of buds. 



304. 



These last mentioned bodies, in the case of our fruit and 

 forest trees, commonly appear, during the time of the second 

 growth, in the axis of the leaves, or at the extremity of the 



