. The fungal diseases of the common larch . Larches. 8 INTRODUCTION longer than the other, so that only one of a pair is cut across in a transverse section of some cushions. Immediately inside the cushions is a continuous cork layer, which kiUs the outer cortex and epidermis, and inside this again is the inner cortex composed of live cells, with intercellular spaces, somewhat thick cellulose walls, and living contents with chloroplasts. A narrow continuous layer of phloem surrounds the wood cylinder, and imme- diately outside the phloem are a few nearly • spherical resin cysts, which look like
. The fungal diseases of the common larch . Larches. 8 INTRODUCTION longer than the other, so that only one of a pair is cut across in a transverse section of some cushions. Immediately inside the cushions is a continuous cork layer, which kiUs the outer cortex and epidermis, and inside this again is the inner cortex composed of live cells, with intercellular spaces, somewhat thick cellulose walls, and living contents with chloroplasts. A narrow continuous layer of phloem surrounds the wood cylinder, and imme- diately outside the phloem are a few nearly • spherical resin cysts, which look like resin ducts in section, but are not extended longitudi- nally. The wood cylin- der may be 4 or 5 mm. in breadth, and contains a few resin ducts ; and in the centre is a star- shaped medulla. Sections of older Fig. ^a transverse section stems show progressive of a one-vear-old stem of larch, ca., cam- stages of thickening. S^±^J:^JZL:^; ii: Theleaf-cusMonsgradu- medullary ray; , outer cortex; p., ally disintegrate and fall Ko^d'- '^w"y^td ''^^*' '^'^" '^"'^ **""* °^' ^^^ ^^^ usuaUy in- distinguishable after the fifth year. New cork layers are formed immediately under the first one. These layers are not always complete, and, in the second year especially, partial layers are frequently formed stretching under the furrows. In general a new cork layer is formed each year. The inner cortex remains living for an indefinite time, but loses its chlorophyll after a while. The phloem becomes thicker, and the outer first- made elements are so stretched tangentially as to leave numerous large intercellular spaces. A fresh ring of wood is put on each year. Detailed structure of tissues : epidermis. The cells measure. 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 perfectly resemble the original Hiley, W. E.
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Keywords: ., bookcentury1900, bookdecade1910, bookpublisheroxfor, bookyear1919
