. A manual of the North American gymnosperms [microform] : exclusive of the cycadales but together with certain exotic species. Bois; Trees; Gymnosperms; Gymnospermes; Arbres; Wood. 126 ANATOMY OF THE GYMNOSPERMS arc p' intei onl; the tra ^MT 'd in vertical series of indeterminate extent, but at varying (if such a nature that they may sometimes be separated a rather thick wall of shori resin cells. At other times J somewhat distant and separated by an extensive vertical jf resin cells. From this it is obvious that in any given plane of section then will be a great diversity / Tv \ \\ ^^ of asp
. A manual of the North American gymnosperms [microform] : exclusive of the cycadales but together with certain exotic species. Bois; Trees; Gymnosperms; Gymnospermes; Arbres; Wood. 126 ANATOMY OF THE GYMNOSPERMS arc p' intei onl; the tra ^MT 'd in vertical series of indeterminate extent, but at varying (if such a nature that they may sometimes be separated a rather thick wall of shori resin cells. At other times J somewhat distant and separated by an extensive vertical jf resin cells. From this it is obvious that in any given plane of section then will be a great diversity / Tv \ \\ ^^ of aspects presented, but I y%--fA \J)p^q C^ in the main exhibitinj; IL^(/>» \> r-\\ \^^~^ structural gradations in the development of the reservoir, as already re- counted. In some cases thick-walled cells of cir- cular outline may be seen in transverse section to stand out from the [;en- eral line of the epithelium and lie within the cavity proper. More rarely such cells are so multiplied as to fill the entire cavity, and they may themselves be filled with granular resin. Such features arc clearly defined (fig. 39), and it is evident from the way in which such cells originate from the epithe- lial cells that they are of the nature of thyloses. A longitudinal section through such a reservoir (fig. 41) shows how such thyloses occupy the entire cavity of the cyst, while in other cases they may be purely local /fig. 40). Among fossil Sequoias similar thyloses form a most characteristic feature in the resin passages of the medullary rays in S. Burgessii and S. Fig. 40. .Sequoia Radia'sec- tion of a resin cyst sliowing the epithelium (£•/.); the central cyst (r.) with a thylosis (t/i.); parenchyma tracheitis (/•), and a tracheid of the lipring wood {Sp. T.). x 300. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not
Size: 1255px × 1990px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookpublisherbostonginnco, books
