. Botany of the living plant. Botany. 198 BOTANY OF THE LIVING PLANT differences suggest different degrees of dependence for organic supply upon some other source than Photo-Synthesis. That source is some fungus which hves within the plant. The fungal filaments are able to penetrate the cell-walls, and pass readily from cell to cell. Usually they are massed in certain zones, especially in the cortex, and are coiled within each cell, the protoplast and nucleus of which still retain their vitality. This indicates that a mutual life is maintained—a condition of symbiosis. The Heath Family shows g
. Botany of the living plant. Botany. 198 BOTANY OF THE LIVING PLANT differences suggest different degrees of dependence for organic supply upon some other source than Photo-Synthesis. That source is some fungus which hves within the plant. The fungal filaments are able to penetrate the cell-walls, and pass readily from cell to cell. Usually they are massed in certain zones, especially in the cortex, and are coiled within each cell, the protoplast and nucleus of which still retain their vitality. This indicates that a mutual life is maintained—a condition of symbiosis. The Heath Family shows generally a mycorhizic condition. The hyphae are present not only in the root of the Common Heather, but also in the stem and leaves, and extend even to the ovary, w^here they may be traced as infecting the seed-coat. The germ is free from them in the seed, but infection takes place shortly after Fig. 149. riG. 149. A single superficial cell of the young root of Common Heather {Calluna vulgaris) lowing the eudotrophic fungus, and its penetration of the cell-walls. (After showi„o ^ Rayner.) ( x 1500.) Without the fungus, as shown by pure sterile cultures, the seedlings do not develop roots, and though they remain alive for months their growth is stopped. On infection with the right fungus they develop normally. Thus the synthesis of fungus and plant has been experi- mentally accomplished. The conclusion is that the Symbiosis is a necessary condition of normal life in the Common Heather. Similar fungal infection of the seeds in the ovary is the rule in other Ericaceae examined. The "outside of the young root of Heather consists of a single layer of large cells, with reduced cortex and a slender vascular strand within. Root-hairs are absent. The outer surface is covered by septate and branched hyphae, w^hich often grow between the cells, while some penetrate the walls. Within the cells they develop several stout coils, with here and there short thick branchle
Size: 2287px × 1093px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjectbotany, bookyear1919
