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is more nearly allied to the animal than to the rock,
floats to the mouth or mouths of the rooted zoophyte, and is of a totally different nature. The plant feasts on unorganized matter, imbibed in a fluid state by the roots and leaves, and never collected into any common receptacle; the animal requires organized matter in a solid state, which is received by a mouth into a stomach, where it is reduced to a semifluid mass; and not till then does the process of assimilation begin. The distinction is broad and clear, and our inquirer will now go on to admire the beautiful mechanism by which the rock, disintegrated by the action of the air, and dissolved by the rain, passes into the vessels of the plant, and there becomes organized, so as to fit it for the stomach of the animal, where it undergoes still farther changes; and finally, produces an organ fitted for the use of a higher order of beings; for it cannot now be doubted that the brain, which is the finest product of animal organization, never is fully called into action till it becomes part of an individual of a yet higher grade. The potass, &c., of the volcanic rock is in great measure inert till it passes into the absorbent vessels of the plant, and the plant is of no use in creation farther than it supplies the nourishment for sentient organism, and the use of the sentient organism, finally, is only demonstrated when a fresh agent is introduced, and the intellectual Will crowns the fair work of Creation. To an observer such as is above described, that link of the chain which connects man with the rock will have a deeper interest than the mere examination of any mechanism, however curious, could inspire: for the announcement that man is formed from the dust of the earth has a deep truth in it which modern science alone can fully appreciate. It is from this dust, that, after the various chemical combinations effected in the cells and vessels of plants and the inferior animals, man derives his corporeal frame, and is, in fact, as far as that portion of his nature is concerned, part and parcel of the earth he moves on; the first step, therefore, in this extraordinary metamorphosis well deserves a careful examination.
CHAPTER I. STRUCTURE AND PROPERTIES OF VEGETABLE TISSUE.
1. VEGETABLE structure—“chemically composed of oxygen, hydrogen, and carbon, to which nitrogen is always superadded,”*—consists, in common with that of all organized beings, of 1. The matter which forms the actual substance of the plant itself. 2. One or more liquids, either contained in, or secreted by, its organs. 3. Other substances, more or less solid, deposited during the passage of those liquids through the different portions of the body. The researches of modern investigators, aided by the improved powers of the microscope, have shown that the solid structure of plants consists of, Cellular Tissue, Vessels, Fibres, and Skin. 2. Cellular Tissue (contextus cellulosus), is a membranous tissue, very similar, in arrangement and form, to a honeycomb, being composed of detached cells, as its name denotes, which are closed, and adhere more or less nearly together; it is found universally in all plants; and many of the lower tribes, such as lichens, mosses, &c., are entirely formed of it. It surrounds the vascular parts so that
* Lindley’s Elements of Botany, p. 1.
in the vegetable as in the animal conformation, no vessel is ever exposed and bare. The diameter of the cells, or vesicles, which is perhaps their more correct appellation, varies considerably, from the thiro tieth to the three-thousandth of an inch ; their shape also is much diversified, but the normal form appears to be round, and it is probable, indeed almost certain, that the variety depends on the pressure of one part of the plant on another during its growth. The vesicles seem to originate from a point, called by modern writers a cytoblast,” which sometimes continues visible after they have reached maturity. The property of uniting firmly together, possessed by the cells which compose this tissue, forms a very important part of the history of vegetation, for it is to these adhesions in the cellular tissue, that all the seams in the various organs of a plant are owing. The term parenchyma is applied to the cellular tissue, considered as a mass, to distinguish it from those parts which abound in vessels. Cellular tissue “is self-productive, one cell not only having the power of generating another on its surface,” but cells frequently produce others, generally in a definite number, within their own cavities, on the complete development of which, the parent cell generally perishes or is re-absorbed. 3. Vessels, or Vascular Tissue. This term is applied to tubes, nearly or quite cylindrical, which are observed in the greater number of plants. They are now usually distinguished as Spiral Vessels and Ducts. A. Spiral Vessels, or Tracheae, resemble a ribbon which has been rolled round a cylinder, and
* Probably from wirot a cavity or hollow point,8xaret a branch or sprout.