Conversations on Vegetable Physiology (Volume 1 ); Comprehending the Elements of Botany, with Their Applicaton to Agriculture

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1832. Excerpt: ... 112 CONVERSATION VI. ON CAMBIUM, AND THE PECULIAR JUICES OF PLANTS. MRS. B. Having traced the sap in its ascent to the extremity of the leaves, and converted it, by the changes it undergoes in that chemical laboratory, into an homogeneous liquid adapted to the nourishment of the plant, we must now, following it in its descent, observe in what manner it performs this office. The sap, thus changed, assumes the name of Cambium, or returning sap, and descends chiefly through the liber, or most internal layer of bark, and a small portion through the alburnum, or young wood. CAROLINE. Having compared the ascending sap to chyle, Mrs. B., we may find a still greater analogy between the cambium and blood, into which chyle is converted, after having passed through the heart and lungs, and been rendered fit to nourish the animal frame. MRS. B. We have already observed, that the chemical changes which take place in the leaves, in order to convert the sap into cambium, are in many respects analogous to those which take place in the heart and lungs, in order to convert the chyle into blood. EMILY. True i in both cases the atmosphere is the agent; with this difference, however, that it carries off carbon from the animal system, while it is the means of accumulating carbon in that of vegetables. CAROLINE. But if the cambium descends through the liber, how does it find its way in endogenous plants, which have no bark? MRS. B. Its passage in monocotyledons has not been well ascertained. It is probable that the fibres of the wood are the medium through which the sap both ascends and descends. As the vessels of plants are so minute as barely to be discernible by the aid of a microscope, it is impossible to examine them with accuracy. And a still greater difficulty attaches t...