National Geographic : 1892 Mar 21
H. F. Reid-Studies of Muir Glacier. late and early wood, although they are represented in the draw ing only in the latter. A specimen of recently grown spruce was obtained by Mr Reid from Alaska,[*] and I have compared it carefully with the preceding and find that the two agree in every structural detail. Figures of transverse and longitudinal sections of the recent wood are not given, since they would be merely repetitions of figures 4 and 5. The size and shape of the medullary rays are essentially the same, and the average number of rays per square millimeter of section is the same in the two specimens. Resin canals are occasionally seen in the midst of a thickened medullary ray in the modern wood, and while I have not observed them in the buried-forest wood, yet I have no doubt that they would be found by persistent sectioning. Transverse sections of the new wood show the same differentiation between the earlier and later cells of the annular ring. The modern wood is several shades lighter than the old, and the brownish tinge of the grain is due to the color of the medullary tissue. The conclusion would be warranted, upon the evidence above given, that the wood taken from a forest at one time buried under glacial deposits in Alaska and submitted to me for examination by Mr Reid is specifi cally identical with that of the Alaskan spruce (Abies sitkensis or A. menziesii) which grows in the neighborhood of the glaciers of Alaska to-day, provided that microscopical examination of the wood alone could be relied upon for the determination of species of coniferous trees. Unfortunately for the student of this subject, the structure of the wood must be supplemented by other char acters before the species can definitely be settled. The preced ing observations can, however, be said to render quite probable, at least, the conclusion intimated above. ADELBERT COLLEGE, March 14, 1891. [*] This was sent to me from Juneau by Reverend Eugene S. Willard. H.F.R.
1892 May 15
1892 Feb 19