406 CONSERVATIVE ORGANS. [LECT. VIII. 



its own organic powers it forms a branch, and 

 becomes a part of the tree or shrub which has 

 produced it. 3. That every adventitious bud, or 

 bud appearing at any after period, originates in a 

 germ generated at the development of the stem or 

 branch on which it appears, although it has 

 hitherto remained latent. 4. That every latent 

 germ is annually carried forward, in a horizon- 

 tal direction, through every concentric zone of 

 wood, intermediate to the medulla and the sur- 

 face on which it will sprout. into a branch; leav- 

 ing behind it a substance of a peculiar structure, 

 somewhat resembling a white cord penetrating the 

 ligneous zones, by which its progress can be 

 traced. 5. That every branch when fully deve- 

 loped, displays the same structure as the stem. 



In examining the structure of the ROOT in 

 ligneous Dycotyledons, it will be useful to follow 

 the division of this organ into caudex, radicles, and 

 ^fibrils, which I adopted in describing the external 

 characters of roots in general; and to examine 

 each part separately, beginning with the caudex. 



a. The Caudex. Taking the Horse Chesnut 

 still as the subject of our examination, we find 

 that the caudex of the root consists of the same 

 parts as are found in the trunk of the tree, ar- 

 ranged in the same relative order, and that each 



