ENQUIRY INTO PLANTS, I. ii. 6-111. i 



again call only the inner part of the core itself 

 the 'heart,' while others distinguish this as the 

 ' marrow.' 



Here then we have a fairly complete list of the 

 'parts,' and those last named are composed of the first 

 'parts' ; wood is made of fibre and sap, and in some 

 cases of flesh also; for the flesh hardens and turns to 

 wood, for instance in palms ferula and in other 

 plants in which a turning to wood takes place, as in 

 the roots of radishes. Core is made of moisture and 

 flesh : bark in some cases of all three constituents, 

 as in the oak black poplar and pear ; while the 

 bark of the vine is made of sap and fibre, and that 

 of the cork-oak ^ of flesh and sap. Moreover out of 

 these constituents are made the most important 

 parts,- those which 1 mentioned first, and which may 

 be called ' members ' : however not all of them are 

 made of the same constituents, nor in the same 

 proportion, but the constituents are combined in 

 various ways. 



Having now, we may say, taken all the parts, we 

 must endeavour to give the differences between them 

 and the essential characters of trees and plants taken 

 as wholes. 



Definitions of the various classes into which plants may be 

 divided. 



III. Now since our study becomes more illumin- 

 ating 3 if we distinguish different kinds,* it is well to 

 follow this plan where it is possible. The first and 

 most important classes, those which comprise all 

 or nearly all * plants, are tree, shrub, under-shrub, 

 herb. 



A tree is a thing wliich springs from the root with 



23 



