Publisher's Synopsis
This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1900 edition. Excerpt: ...lead to the replacement of parts which have a brief existence, and need to be renewed. This is the case, for instance, in forest trees that have attained their full dimensions. Growth in the vegetable organism is very definitely localised. Growth in length takes place at or near the apices of stems and roots; it has a definite though vari: able localisation in leaves of different kinds. Growth in thickness is confined to sheaths or bands of cells in different regions of the axis, such as the cambium, and the different phellogens met with in the cortex. Growth and nutrition differ in another respect: the former is intermittent, the latter needs to be constant, though the intensity of the requirements may vary. These considerations show us that there must exist in the plant a very complete mechanism by which the different food-stuffs can be circulated about its body. Each protoplast must be in receipt of a continuous, though perhaps small, supply of nutritive material; the demands of growth must be satisfied by the transport of considerable quantities of formative material to the growing regions. The intermittence of growth makes a further demand. Consider one among many places at which a large consumption of such formative material is proceeding: a stream is travelling there to supply the need. Suppose that some temporary check to the growth at that spot takes place. The stream will lie diverted elsewhere by the demands of the other growing parts, and when the hindrance is removed and growth should again proceed, there will be no stream of constructive material, and much time will be lost before it can be restored. To prevent this there should be a storage of food close to the seat of its consumption, so that, with the awakening need, the...