. Le cytoplasme de la cellule végétale. Les cellules et tissus végétaux ; protoplasme. miH' © [0 d. Fig. 75 (à gauche). - Selaginella kraussiana. 1, l'extrémité de la tige végétative, chaque cellule contenant chondriosomes (C) et un peu plus grande (P) des plastes accolées au noyau. 2, schéma de développement au cours de la différenciation cellulaire des plastes. (Après Emberger) . Fig. 76 (droit). - Selaginella kraussiana. Plaste (P) dans les cellules de parenchyme vivant de la tige. (Après Emberger). Dans le même temps diminuer progressivement en volume, de sorte qu'elles prennent, peu à peu, l'apparition de petits éléments qu'il

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. The cytoplasm of the plant cell. Plant cells and tissues; Protoplasm. miH' © [0 d. Fig. 75 (left). — Selaginella Kraussiana. 1, vegetative tip of the stem, each cell containing chondriosomes (C) and a slightly larger plastid (P) appressed to the nucleus. 2, Diagram of developing plastid during cellular differentiation. (After Emberger) . Fig. 76 (right). — Selaginella Kraussiana. Plastid (P) in living parenchyma cell of the stem. (After Emberger). at the same time diminish progressively in volume, with the result that they take on, little by little, the appearance of small elements which it becomes impossible to distinguish from the chondriosomes. The same phenomena occur in the formation of the antherozoids. The fertilized egg resulting from the fusion of these cells shows, therefore, a homogeneous chondriome. In the embryo, some of the elements of this chondriome differentiate anew. In the leaves they become chloroplasts, in the stem and root they become large chon- drioconts which represent the starch-forming plastids. In the epidermal cells of leaves which will produce sporangia, both chloroplasts and inactive chondriosomes are encountered. In the young sporangia, however, the chloroplasts again lose their chlorophyll and appear as typical chondriosomes, indistinguishable from the inactive chondriosomes. From the time that the spore begins germination, these typical chondriosomes grow larger, be- come impregnated with chlorophyll and take on again the character of chloroplasts.. 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 work.. Guilliermond, Alexandre, 1876-; Atkinson, Lenette May Rogers, 1899-. Waltham, Mass. , Chronica Botanica Company

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