. An introduction to vegetable physiology. Plant physiology. METABOLISM 269 particular substances are formed by tbe direct decomposi- tion of protoplasm, or by subsequent changes in the primary products of such decomposition. Till quite recently the formation of resin and allied bodies in the resin passages of the Conifers and in many glandular hairs was con- sidered a true secretion, the aromatic substances being held to arise in the cells. Eecent investigations tend to show that this is not the mode of their origin at all, but that these substances are formed by a peculiar process of degrada
. An introduction to vegetable physiology. Plant physiology. METABOLISM 269 particular substances are formed by tbe direct decomposi- tion of protoplasm, or by subsequent changes in the primary products of such decomposition. Till quite recently the formation of resin and allied bodies in the resin passages of the Conifers and in many glandular hairs was con- sidered a true secretion, the aromatic substances being held to arise in the cells. Eecent investigations tend to show that this is not the mode of their origin at all, but that these substances are formed by a peculiar process of degradation of the cell-wall. The glandular hairs of Primula sinensis (fig. 124), and the more complex one of the Hop (fig. 125). Fig. 124.—Glandular Hairs from Primula sinensis. <t, young hair ; b, hair showing secre- tion formed in the cell-wall of the terminal cell; c, hair after dis- charge of tbe 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 Green, J. Reynolds (Joseph Reynolds), 1848-1914. Philadelphia, P. Blakiston
Size: 1569px × 1592px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., book, bookcentury1900, bookdecade1900, booksubjectplantphysiology
