any tree in tile grove. What is more, it was likewise 

 without all pith, being hollow within as a drum. Add 

 to this, that the plane and cork trees divest themselves- 

 every year of all their old bark (as snakes do of their 

 skins) and acquire a new one. Now during the change 

 from one to the other, it is clear they are not nourish* 

 ed by the bark :. therefore there must be other vessels 

 besides those of the bark capable of conveying the sap. 

 It is probable the bark may ordinarily do this ; but 

 that when the ordinary conveyance fails, some of the 

 woody parts (which were ail sap-vessels once) resume 

 their ancient office ; so far, at least, as to keep the 

 tree alive, though not to increase its bulk Perhaps 

 this is the use of the sap-vessels in the wood different 

 from that of those in the bark. These are designed 

 for the continuation, of a tree; those in the bark for 

 its augmentation. 



It seems the bark in fruit trees is principally de- 

 signed for the augmentation of the tree itself, while 

 the finer vessels of the woody part, strain and prepare 

 the juices for the fruit. A gentleman near Cork, ob- 

 serving that his peach-tree grew exceedingly," but bore 

 no fruit, cut off the bark almost quite round, for the 

 breadth of two fingers. The next year the tree hardly 

 grew at all, but bore abundance of fruit. 



Again. As animals are furnished with the cellular 

 membrane, which iinests and covers all the fleshy 

 parts, and screens them from external cold, so plants 

 are encompassed with a bark, replete with fleshy juices, 

 by means whereof even the winter cold is kept off ? and 

 hindered from freezing the juices in the vessels ; and 

 those sorts of trees, whose bark abounds with oil 5 re- 

 main green all the year round. 



5. In the Wood likewise there are observed con* 

 cave fibres, woven as it were of various vesicles, and 

 stretching all the length of the wood, as do the fibres 

 of the bark : these have intervals between them, in 

 which are transverse vesicles reaching to the very pith. 

 There are other fibres, which run obliquely, and are 



