298 OKIGHKAL AETICLES. 



XXIX. — The Structuee of the Stem in Dicotyledons; being 

 References to the Literature of the Subject. By Pro- 

 fessor Oliver, E.L.S. 



It is my aim in the present communication to embrace references, 

 under the heads of the respective Natural Orders, to all the recent 

 literature which I have been able to find, referring to the internal 

 structure of the axis of woody Dicotyledons in respect of the arrange- 

 ment of the tissues and microscopic character of the cells and vessels. 

 Upon the subject of the anatomy of the axis — which has not 

 been greatly pursued by English botanists, — we have very numerous 

 observations on record, but these want extending and correlating 

 before any satisfactory generalisations can be based upon them, and 

 the fii'st steps of progress appear to be supplied by the collecting of 

 these scattered data. 



These references are mostly very brief and without much abstract 

 or comment, unless my o^vn or other observations have suggested 

 any. "When the figures of wood-structure in the elementary works 

 which I have seen aj)peared to be worthy of mention I have given a 

 reference to them. The plates of Grew,* Maljjighi,! Leeuwenhoek, J 

 Hill,§ and other of the fathers of phytotomy I have not thought it 

 needful to quote. In the essays of H. v. Mohl, and numerous other 

 writers upon general structural questions, much special information 

 is often included which it would be an endless labour thoroughly to 

 single out and refer to here. I have, however, endeavoured to notice 

 all the more important cases in which wood-structure is thus inci- 

 dentally described. Brief notes are added upon a few of the specimens 

 and preparations contained in the Museum of the Royal Grardens 

 at Kew, at least in those instances in which they have indicated 

 interesting structural features. I refrain, in this communication, 

 from touching upon the bearing which stem- structure may have upon 

 Systematic Botany and Palaeontological Research, as well as from 

 entering upon a discussion of the obscure and difficult subject of the 

 relations which may be traced between the structure of the tissues 

 and their function, and between the character of the axis generally 

 and that of the floral-organs, upon which latter, indeed, it may be 

 that the operations of systematists have been hitherto a little too 

 exclusively based. I do not apprehend, however, that in respect to 

 practical Systematic Botany, the methods usually accepted of esti- 

 mating affinity, resting upon floral structure, are likely to derive 

 from the anatomical structure of the stem an aid other than cor- 

 roboratory, corresponding in some measure to that aff'orded by the 

 sensible properties of plants. 



• Anatomy of Plants, 1682, with diagrams of the Structm-e of the Vine, HoHy, 

 Hazel, Barberry, Apple, Pear, Plum, Ehn, Ash, Walnut, Fig, Pine, Oak, Sumac, &e. 

 •j- Anatome plantarum, 1G73. X Arcana Naturae. 



§ The Construction of Timber, 1770. 



