The natural history of plants, their forms, growth, reproduction, and distribution; . t quantityof alkaloids and bitter substances, which prevent ruminants from devouringfoliage, should be brought to the right places at the right time. In connectionwith the process of rejuvenescence and multiplication also, it is necessary thatthose cells and groups of cells, which become detached from the plant-shoot andjourney out into the wide world as spores and seeds, should be equipped with MECHANISMS FOR CONVEYANCE TO AND FRO. 479 a store of materials, so that they may be nourished until they can manufa
The natural history of plants, their forms, growth, reproduction, and distribution; . t quantityof alkaloids and bitter substances, which prevent ruminants from devouringfoliage, should be brought to the right places at the right time. In connectionwith the process of rejuvenescence and multiplication also, it is necessary thatthose cells and groups of cells, which become detached from the plant-shoot andjourney out into the wide world as spores and seeds, should be equipped with MECHANISMS FOR CONVEYANCE TO AND FRO. 479 a store of materials, so that they may be nourished until they can manufacturefor themselves the necessary food from the air, water, and soil. The places wherespores and seeds are produced, therefore, constitute an important destination forcertain journeying materials. Finally, it also happens that in regions where atemporary standstill of the vital activity of the plants occurs, and where thesucculent green foliage is liable to be dried up by the periodic drought, or frozenby the winter cold, all the useful substances are withdrawn from the threatened. .,iiiii.{„ Fig. 129.—Leafless Branches of Tecema radicans, rooted on a walL leaves, and are deposited in a suitable form in safe places, and stored up foremployment later. In these instances, these safe places, these storehouses orreservoirs, form the destination of the transported materials. Not only are there channels of distribution to the various destinationsenumerated, but we find even distinct routes provided for the different substancestransmitted. Investigations have shown that the conducting mechanisms dividethe work to some extent between them. The medullary rays and wood paren-chyma chiefly conduct carbohydrates, the former radially, and the latter longitudi-nally, in the stem. The vascular bundle sheaths of the leaf-veins are particularlyrich in glucosides. Certain tracts of cells in the parenchyma accompanying thevascular bundles in the stem also conduct glucosides, while others cond
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectbotany, bookyear1902
