Feb. 1901.] BOTANICAL SOCIETY OF EDINBURGH 31 



to this view, may be regarded as cousistiug of all the 

 tissues cut off by the pbellouen. The aim of this paper is 

 to give evideuce in favour of the old English definition, aud 

 to show that the translators' definition is founded on a mis- 

 translation. 



Numerous excellent text-books and translations have 

 appeared in English since 1884. In these books, one or 

 other of the two definitions has been adopted, according to 

 the choice or belief of the writer or translator of each. 

 The definitions are incompatible, because the whole is 

 greater than its part. 



Bark is a word which has the same spelling in Danish 

 and Swedish, and the English form comes from the same 

 root as the Anglo-Saxon " beorgau,' to cover or protect. 

 As a purely Anglo-Saxon word it was used by the early 

 English before there was a science of Botany, and it is an 

 unwritten rule that when a popular word with a perfectly 

 defined meaning becomes the technical term of any science, 

 the technical application shall not differ from that in 

 popular use. For example, the wood of many Dicotyledons 

 and Gymnosperms consists of heart-wood {duramen) and 

 sap-wood {alburnum). No one would be justified in calling 

 the former alone the vjood of the tree, but it might be called 

 the " dead wood " or " inner wood," as well as heartwood. 



In the same way, the bark is what lies outside the wood 

 of the tree, and, generally speaking, the phellogen layer 

 may be regarded as separating the " inner, sap-containing, 

 living bark " from the " outer, dry, dead bark "; but no 

 one would be justified in calling the latter alone the harl: 



There may be dead fibres in the living bark, and a layer 

 or two of cells immediately to the outside of the phellogen 

 may still live, but these do not affect the general question. 

 The cambium of the botanist is a layer of embryonic or 

 meristematic tissue, which lies between wood and bark. 

 It gives rise to new wood towards its inner side, and new 

 bast towards its outer side. The bast is therefore the 

 inner surface of the bark, and when it contains fibres 

 among its softer tissues, as in the lime-tree, it is spoken 

 of as liber, which has a certain commercial value under the 

 name of bast. Liber, however, is not a term that is now 

 used by English botanists. 



