S1CT. VI. THE CAUDEX. 



chinks and fissures, as may be seen in the aged 

 trunks of the Elm and Fir. In the root it is 

 said to be generally thicker than in the stem and 

 branches, and of a dull and earthy colour, though 

 affected a little by the soil in which it grows ; but 

 in the root of the Elm it is reddish ; in that of 

 the Berberry it is yellowish ; and in that of the 

 Cytisus of the Alps, it is black. 



In young shoots and branches both from the 

 stem and root, it may be distinguished into the 

 three following parts: 1st, An Epidermis, or ex- 

 ternal pellicle ; 2d, A Parenchyma^ or soft and 

 pulpy substance situated immediately under the 

 epidermis, and constituting a sort of secondary 

 integument ; and 3dly, a number of thin and con- 

 centric layers, forming its interior and principal 

 portion, and generally designated by the name of 

 the cortical layers ; but known also by the appel- 

 lation of the liber. In the root the several layers 

 are said by Du Hamel to be thicker than in the 

 trunk ; but I have not found any notable difference 

 between them in this respect. 



The intermediate portion of the caudex is the In which 

 wood, which constitutes the great body of the 

 full grown plant. In most plants it is whitish, as 

 in the Ash and Fir ; but in the stem of Lignum- 

 vitae and Logwood it is of a deep red ; and in that 

 of the Laburnum it is variegated, at least in aged 

 lubjects. In the full grown tree it is not wholly of 



