136 SEAT OF VEGETABLE LIFE. 



of bark and wood proceed from a member which, from 

 its having- been erroneously identified with the liber 

 or alburnum, has escaped observation merely from its 

 unobvious identity^ and the small space it occupies in 

 its dormant stater It may be best distinguished by 

 considering it as being the inner viscous lining of the 

 liber, and in this position and character it appears 

 during winter as a very thin layer, scarcely distin- 

 guishable from the liber itself. 



That this thin body or indusium is really the seat 

 of life, the following circumstances may be urged as 

 proof; and as they are constantly occurring to the 

 practitioner in the propagation of trees, are the more 

 to be depended upon. 



In the first place we may notice that no fibrous 

 roots are ever produced from the wood or bark in 

 any stage of their existence ; nor do buds ever origin- 

 ate on the bark or wood, except from the first layer 

 which surrounds the pith in the first year of its visible 

 existence ; and which layer, be it remembered, is then 

 in the act of swelling into form, and consequently 

 part of the vital envelope. If a cutting be put in the 

 ground, the first change it undergoes is a visible pro- 

 trusion of cambium from between the wood and the 

 liber, and from which in a short time fibres are ex- 

 serted that become roots. So in the case of layers, 

 the roots all proceed from those parts of the incision 

 where this living member is exposed; and even 

 where no incision is made fibres will be produced, 

 apparently from the bark, but, in fact, originating 



