The Book of Household Management by Mrs. Beeton

led to inquire into the means by which they are enabled to arrive at such strength and maturity; and whether it may be considered as a humiliation we will not determine, but, with all the ingenious mechanical contrivances of man, we are still unable to define the limits of the animal and vegetable kingdoms. "Plants have been described by naturalists, who would determine the limits of the two kingdoms, as organized living bodies, without volition or locomotion, destitute of a mouth or intestinal cavity, which, when detached from their place of growth, die, and, in decay, ferment, but do not putrefy, and which, on being subjected to analysis, furnish an excess of carbon and no nitrogen. The powers of chemistry, and of the microscope, however, instead of confirming these views, tend more and more to show that a still closer affinity exists between plants and animals; for it is now ascertained that nitrogen, which was believed to be present only in animals, enters largely into the composition of plants also. When the microscope is brought to aid our powers of observation, we find that there are organized bodies belonging to the vegetable kingdom which possess very evident powers of locomotion, and which change about in so very remarkable a manner, that no other cause than that of volition can be assigned to it." Thus it would seem that, in this particular at least, some vegetables bear a very close resemblance to animal life; and when we consider the manner in which they are supplied with nourishment, and perform the functions of their existence, the resemblance would seem still closer. If, for example, we take a thin transverse slice of the stem of any plant, or a slice cut across its stem, and immerse it in a little pure water, and place it under a microscope, we will find that it consists principally of cells, more or less regular, and resembling those of a honeycomb or a network of cobweb. The size of these varies in different plants, as it does in different parts of the same plant, and they are sometimes so minute as to require a million to cover a square inch of surface. This singular structure, besides containing water and air, is the repository or storehouse of various secretions. Through it, the sap, when produced, is diffused sideways through the plant, and by it numerous changes are effected in the juices which fill its cells. The forms of the cells are various; they are also subject to various transformations. Sometimes a number of cylindrical cells are laid end to end, and, by the absorption of the transverse partitions, form a continuous tube, as in the sap-vessels of plants, or in muscular and nervous fibre; and when cells are thus woven together, they are called cellular tissue, which, in the human body, forms a fine net-like membrane, enveloping or connecting most of its structures. In pulpy fruits, the cells may be easily separated one from the other; and within the cells are smaller cells, commonly known as pulp. Among the cell-contents of some plants are beautiful crystals, called _raphides_. The term is derived from [Greek: rhaphis] a _needle_, on account of the resemblance of the crystal to a needle. They are composed of the phosphate and oxalate of lime; but there is great difference of opinion as to their use in the economy of the plant, and one of the French philosophers endeavoured to prove that crystals are the possible transition of the inorganic to organic matter. The differences, however, between the highest form of crystal and the lowest form of organic life known, viz., a simple reproductive cell, are so manifold and striking, that the attempt to make crystals the bridge over which inorganic matter passes into organic, is almost totally regarded as futile. In a layer of an onion, a fig, a section of garden rhubarb, in some species of aloe, in the bark of many trees, and in portions of the cuticle of the medicinal squill, bundles of these needle-shaped crystals are to be found. Some of them are as large as 1-40th of an inch, others are as small as the 1-1000th. They are found in all parts of the plant,--in the stem, bark, leaves, stipules, petals, fruit, roots, and even in the pollen, with some few exceptions, and they are always situated in the interior of cells. Some plants, as many of the _cactus_ tribe, are made up almost entirely of these needle-crystals; in some instances, every cell of the cuticle contains a stellate mass of crystals; in others, the whole interior is full of them, rendering the plant so exceedingly brittle, that the least touch will occasion a fracture; so much so, that some specimens of _Cactus senilis_, said to be a thousand years old, which were sent a few years since to Kew, from South America, were obliged to be packed in cotton, with all the care of the most delicate jewellery, to preserve them during transport. [Illustration: SILICEOUS CUTICLE FROM UNDER-SIDE OF LEAF OF DEUTZIA SCABRA.] [Illustration: SILICEOUS CUTICLE OF GRASS.]