74 JOURNAL OF THE [May, 



by the large vessels or ducts, many smaller ones are interspersed, 

 not in concentric rows, but inclined from a radial direction 

 to the centre of the tree ; they gradually decrease in size to 

 the outer portion of the ring. Surrounding these smaller ducts 

 are tissues which may be classed as tracheides, being quite long 

 and having an abundance of circular thin places in their walls. 



Interspersed all through the bundle or ring are cells, possibly 

 cambiform cells, with thin walls, which, in the alburnum, during 

 the autumn and winter, contain starch grains. In this part of 

 the wood, during the same season, the medullary rays also con- 

 tain starch. The transverse walls in these cells are frequent, 

 every three or four diameters in length containing a division. 

 Another class of cells of much greater length, but little larger in 

 size, are constricted at the transverse cell-wall, giving the 

 appearance of slightly rounded ends. These do not differ much 

 in appearance from the vertical cells in the Sequoias, which con- 

 tain coloring matter. I tested them for tannin and they indi- 

 cated its presence, but other cells also did the same. 



The libriform cells in this wood have comparatively thin 

 walls, and a large lumen. The quadrangular fibres surrounding 

 the large vessels measure from 25 to 30^ in diameter, while the 

 lumen measures from 19 to 25^1/. The libriform fibres near the 

 central and outer portion of the ring measure from 19 to 25 ^< in 

 diameter, the lumen measuring from 10 to 15U in diameter- 

 Nearly solid fibres are not found in this wood as in Carya alba, 

 a closely allied tree. 



In the tangential section, the medullary rays are found in 

 single and in double rows ; the former predominating. From 

 one to thirty cells form the single vertical bundles — and in the 

 others often only one or two cells are doubled. This wood splits 

 easily. From the microscopical examination of this wood, one 

 would class it as one of medium softness, which is found to be 

 true by other tests. Its specific gravity ranges from .4 to .5 of 

 ox\Q per cent.; a cubic foot of dry wood weighing from 26 to 32 

 lbs. In contact with the ground it is very durable, and when 

 used for railway ties does not decay before the fibres are de- 

 stroyed under the rails. 



The large vessels it contains give veneers cut from the second- 

 growth wood a beautiful appearance, and it is much used for 

 interior finishing. 



