VEGETABLE SAP. 125 



above the base of every branch of a tree ; or round 

 a place whence numerous shoots have been repeat- 

 edly browsed off (Fig. 37). Beech and elm trees 

 frequently present malformations of this kind; some- 

 times by large tumours formed within the bark 

 united to, and being projecting parts of, the woody 

 axis, and occasionally by insulated portions of lig- 

 neous matter involved in the bark and easily separable 

 therewith. The same kind of protuberance is often 

 formed at the base of cuttings previous to the ejection 

 of fibres (Fig. 38) ; and also round a wound on a 



Fig. 38. 



stem, particularly at the upper side (Fig. 39). Such 

 accidental eruptions on old trees continue to be 

 enlarged for many years, and receive annual additions 

 of bark and wood, like any other part of the trunk ; 



