120 



composed by the interweaving of a prodigious number 

 of fibres, is one of the principal instruments of these 

 preparations. The more or less perfect analogy of the 

 juices proper to the subject with those that are peculiar 

 to the graft, favours hi a greater or less degree the un- 

 folding ol the latter. The nearer or more distant rela- 

 tion between the time in which the sap in the subject 

 continues, and that in which the graft has been accus- 

 tomed so to do, contributes likewise more or less to the 

 success of the operation. 



9. The body of the plant is in a continual state of mo- 

 tion. It always tends to produce, either the bark, a 

 bud, or a root. Make an incision in a tree : the wound 

 will cicatrise. A greenish roll will in a short time be 

 seen at the top of the wound, afterwards on the sides, 

 and at length towards the bottom. This roll is a new 

 rind, which i& about to cover the wood again, without 

 uniting to it. Observe what passes with respect to this ; 

 you will perceive in it certain distinct and glutinous nip- 

 ples, and small reddish spots dispersed here and there, 

 which you will find to be a growing bark. A matter 

 that is parti) transparent, whitish, and mucilaginous, will 

 seem to raise up this bark. All these glutinous sub- 

 stances will thicken, increase in length, and become 

 stronger, and in a little time what was at first of a gluey 

 nature will be herbaceous, cortical, and ligneous. The 

 cicatrice will at length entirely close itself, and restore 

 the communication between all the vessels. 



The w.Qod does not only differ from the lark by its 

 density, but it has likewise organs that are not to be 

 met with in the latter. It seems to be peculiarly pos- 

 sessed of air-vessels. When a new rind seems to con- 

 vert itself into wood, this conversion is only in appear- 

 ance. Nature does not create more air-vessels than are 

 suited to one entire plant. f But a multitude of fibres, 

 that are destined to become wood, pre-exist under the 

 new rind, and unfold themselves with it and by it, as we 

 see the butterfly unfold itself in and by the caterpillar. 

 Whilst wood is nothing more than a mucilaginous drop, 



