LETTER XIII. 



141 



it by the Cambium, whose proper office it is to provide 

 the roots. The two forming but one body — the Cam- 

 bium being but an appendage to the bud — each exerts 

 its own innate tendency ; and, while the bud sends up 

 the shoot or stem of the plant, the Cambium-layer (or 

 that particular portion of this which stands imme- 

 diately related to that particular bud) evolves the 

 root — superseding thereby the necessity of any effort 

 in this direction on the part of the bud. That the 

 bud, however, is capable of successfully exerting itself 

 in this way appears from what is represented in the 

 adjoining figure (Fig. 19), as Fig. 19.* 



occurring in the Dracoena ; and 

 likewise from a circumstance 

 mentioned by M. Richard. He 

 states that he had seen in the 

 possession of M. Du Petit- 

 Thouars, a branch of Rohinia 

 pseudo-acacia on which Rohi- 

 nia hispida had been grafted. 

 The stock had died ; but the 

 graft had continued to grow 

 notwithstanding. And thus growing, it had given off 

 from its base a sort of plaster (une sorte d'empate- 



* Truncated stem of a Dracoena after maceration, shewing the 

 radicular woody fibres of the branch (r) overspreading a portion of 

 the stem (/) • *5 tracheae of the stem and branch. — From 



Balfour's Class-Book of Botany, p. 447. 



