. A manual of the North American gymnosperms [microform] : exclusive of the cycadales but together with certain exotic species. Bois; Trees; Gymnosperms; Gymnospermes; Arbres; Wood. RESIN CELLS ,,, but only about half fills it longitudinally. This section is the most useful for displaying the relations of the idioblasts to the adjacent tracheids, inasmuch as the limits of the walls of the latter are much more clearly defined. As seen the tange ial section, the Idioblasts fall into a single longitudinal series, which may not embrace more than two or three members, but more commonly there ar
. A manual of the North American gymnosperms [microform] : exclusive of the cycadales but together with certain exotic species. Bois; Trees; Gymnosperms; Gymnospermes; Arbres; Wood. RESIN CELLS ,,, but only about half fills it longitudinally. This section is the most useful for displaying the relations of the idioblasts to the adjacent tracheids, inasmuch as the limits of the walls of the latter are much more clearly defined. As seen the tange ial section, the Idioblasts fall into a single longitudinal series, which may not embrace more than two or three members, but more commonly there are upwards of twency^ne in a series. Not infrequently the Cham of crystals will be found to be interrupted for some httle distance, but the continuity of the idioblasts will then be seen to be uninterrupted through the development of cylindrical elements of uniform but smaller diameter and devoid of crystals from which it would appear that the lenticular or rounded form! as determined by the particular plane of section, is not the normal form of the cell, but that such special form results from the growth of the crystal, which must have been deposited when the tissue was in a formative stage of development. This is made apparent in another very striking manner. In any tangential exposure of such a series it may be seen that the terminal mem- ber does not necessarily occupy all the space between the walls of adjacent tracheids. There is thus developed an intercellular space of variable dimensions, which may be quite small or may be so extensive as to suggest that the crystals were formed in such spaces and not in closed cells. Such spaces are obviously not the result of that splitting which is ordinarily incident to the growth of tissues, but they clearly arise as a secondary effect incident to the development of the crystalline mass and the pressure of this latter upon the surrounding parts. Resin Cells' In a large proportion of the Coniferales the wood is character- ized by the
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