168 CONIFEEALES 



[CH. 



prefix is employed, e.g., Xenoxylon, and some authors make use 

 of a name, e.g., Woodworthia, which does not indicate that the 

 diagnosis is based on anatomical features. Conwentz 1 adopted 

 the method of adding the prefix Rhizo- to generic terms for wood 

 believed to belong to roots, and Felix 2 and Lignier 3 have employed 

 the prefixes Cormo- and Clado- for stem- and branch- wood respec- 

 tively. It is, however, seldom that such differentiation is possible 

 and it is questionable whether it is wise to attempt refinements o 

 this kind. Barber 4 , in his critical paper on a species of Cupressino 

 xylon, calls attention to Strasburger's description of an old mori- 

 bund stem of Larix with root-like characters and Gothan 5 speaks 

 of a branch of Pinus silvestris with root-attributes. The differences 

 between branches and the main stem are not sufficiently known 

 even in the more familiar types to justify the use of the prefixes 

 Cormo- and Clado- in descriptions of fossil specimens. 



The scientific study of fossil wood began with Nicol 6 and 

 Witham whose work was rendered possible by methods of section- 

 cutting first employed, according to Nicol, by a Mr Sanderson, 

 lapidary. Opinions expressed by Nicol on methods of investi 

 gating petrified wood are still pertinent aftei a lapse of 80 years : 

 'To pronounce with certainty whether a fossil Conifer be essen- 

 tially different from any known individual of the recent kind, it 

 would be requisite to have a thorough knowledge of the structure 

 at least of all the different tribes of recent Coniferae; and yet 

 several distinct fossil genera have been indicated by a person who 

 has examined, and that too very superficially, only three slices of 

 three recent Pines, differing not essentially .from one another.' 

 In recent years the tendency has been towards a more detailed 

 study of anatomical characters such as the distribution and form 

 of the pits on medullary-ray cells. The facts recorded in the 

 Chapter on Recent Conifers illustrate the difficulty of arriving at 

 a thoroughly satisfactory classification of anatomical features that 

 may serve as criteria in the identification of recent genera : even 

 in the case of well-preserved fossil wood we have as a rule to rest 

 content with a generic name denoting a combination of characters 

 met with in more than one existing genus. Moreover, as already 



1 Conwentz (80) A. 2 Felix (82). 3 Lignier (07 2 ). 



4 Barber (98). * Gothan (05) p. 19. 6 Nicol (34) A. p. 141. 



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