CONTENTS. 



XVll 



downwards new roots, these roots in their descent pass 

 alongside the shoot and the roots of the plant of the pre- 

 vious year, and thence extend a short way beyond into fresh 

 soil. And so on. Disposition of the bark. The terminal 

 bud and its relation to the pith contained in the medullary 

 cavity. Qualification of the statement that the plants issu- 

 ing from the buds actually send down roots. 



LETTER V. 89 



Examination of the parts composing the Exogen, as viewed 

 horizontally or in the transverse direction. Cellular tissue. 

 Relation of the woody tissue to the cellular. Medullary 

 or pith cavity, medullary rays, medullary ring or cam- 

 bium, and bundles of woody tissue. Disposition of the 

 woody bundles often irregular — eccentric character thus 

 given to the concentric woody rings. Gfrouping of the 

 woody bundles into sets or parcels — columnar or buttressed 

 character thus given to the trunk. Winding or erratic 

 course of woody fibres or bundles. Identity of woody tissue 

 above ground with that underground. Antagonism 

 between the woody and the cellular tissue. Elm at North 

 Stoneham, Hants, with roots filling up the decayed bole. 



LETTER VI. 49 



Examination of the parts composing the Endogen. The palm 

 — disposition of its parts. Bud of palm — sends upwards 

 leaves and fiowers, and downwards roots— these roots pass 

 inside the remains of the palm-plants of former years. The 

 palm-plant has no proper stem, and the palm-tree no pro- 

 per trunk. Roots of the palm-tree fibrous like those of 

 grasses, and derived from the palm -plants of the first few 

 years. Aerial roots of certain palms, piercing through the 

 trunk, passing down through the air into the soil, and form- 

 ing props for the support of the palm-trunk. Slender hold 

 which the palm-tree has of the ground. 



LETTER VII . 54 



Harmony of the Corporation-theory of trees with the known 

 history of many trees still extant and remarkable for their 



h 



