144 VEGETABLE ORGANOGRAPHY. 



the woody body. Each of these parts presents two 

 portions, which are distinct, and placed in an inverse 

 direction to one another. The parenchymatous part of 

 the woody body, the Central Pith {moelle centrale,) or 

 the Pith (moelle) properly so called, occupies the 

 centre ; and the fibrous part, which composes the Wood 

 (hois) and the Alburum (auhier), is disposed in 

 layers around the pith. On the contrary, in the bark, 

 the parenchymatous part, or the Cortical Pith 

 (moelle corticale), which bears the nameof the Cellular 

 Envelope, (ejiveloppe cellulaire,) is found on the 

 outside ; and the fibrous part, which includes the Cor- 

 tical Layers, (couches cortkales,) and the Liber 

 (liber), is in the interior. The woody and corticcd bodies, 

 then, are two parts organized in an inverse direction to 

 one another. We shall first study each of these organs 

 considered separately, in order afterwards to give some 

 general observations upon them taken together. 



Art. J. — Of the Central or Woody System. 

 § \. — General Considerations. 



The Central vSystem or Woody Body of a tree, taken 

 collectively, is composed of an indefinite number of 

 very elongated cones, inserted upon one another ; and 

 which, when cut horizontally, present so many concentric 

 layers. Each of these layers is composed, as Dutrochet 

 has well established, of two principal parts; — 1st, a band 

 of cellular tissue, situated on the inner side ; and, 2d, a 

 band of fibres, or bundles of vessels and elongated 

 cellules, placed on the outer side. Consequently, the 

 innermost or oldest layer presents the band of cellular 



