NOTES. 



235 



1841 (p. 828) ; others have been occasionally met with ; and 

 Link has figured one in his Icones Selectee (Part ii., t. 2, fig. 7), 

 which he speaks of thus : — ' I found such letters in a Lime- 

 tree near Berlin, on an estate belonging to the deceased mini- 

 ster, Count Yon Luttum ; the letters on the one side of the 

 split piece were hollow, on the other elevated, and the cavity- 

 had evidently been filled up again with a woody substance. 

 This fiUing-up substance, on making a transverse incision, 

 exhibited rather irregular layers, with a moderate magnifying 

 power. And on being magnified 315 diameters, it evidently 

 consisted of strata of larger and smaller cells, partly filled up, 

 partly empty, with interstices. The circumstance, however, 

 which appears particularly remarkable, is, that the internal 

 structure of the fiUing-up substance, on a longitudinal incision, 

 corresponded very nearly vfith the old wood situated next to 

 it, with the difi'erence only, that spiroids existed in the latter, 

 which were entirely absent in the new wood. It will be seen, 

 therefore, that the formation of layers is peculiar to the wood, 

 and is by no means caused by external influences.' " — Intro- 

 duction to Botany, vol. ii. Pp. 197-201. 



This whole extract bears on one particular view of the 

 woody tissue and its mode of evolution — that which regards it, 

 exclusively, as descending matter^'''' and evolved by the actual 

 descent of this matter /rom the leaves. The greater number of 

 the objections to this view seem to be satisfactorily met and 

 answered by Dr Lindley. There are other objections, how- 

 ever, not so easily disposed of, regarded seemingly by Dr 

 Lindley as real, and pointing to a superficial deposit in situ., 

 from the Cambium, as the actual mode of its evolution. It 

 appears to me that the view taken in the text, which recognises 

 both modes of evolution — an evolution in situ as well as an 

 evolution hy descent — not merely solves all the difficulties, but 

 is required to explain all the phenomena connected with the 

 formation of the woody tissue. 



