Sec. 6. Protoplasm
Protoplasm is an albuminoid substance, ordinarily resembling the white of an egg, consisting of carbon, oxygen, nitrogen, and hydrogen in extremely complex and unstable molecular combination, and capable, under proper conditions, of manifesting certain vital phenomena, as spontaneous motion, sensation, assimilation, and reproduction, thus constituting the physical basis of life of all plants and animals; sarcode. It is essential to the nature of protoplasm that the substance consist chemically of the four elements named (with or without a trace of some other elements); but the molecule is so highly compounded that these elements may be present in somewhat different proportions in different cases, so that the chemical formula is not always the same. The name has also been somewhat loosely applied to albuminous substances widely different in some physical properties, as density or fluidity. Thus the hard material of so-called vegetable ivory and the soft body of an amœba are both protoplasmic. The physiological activities of protoplasm are manifested in its irritability, or ready response to external stimuli, as well as its inherent capacity of spontaneous movement and other indications of life; so that the least particle of this substance may be observed to go through the whole cycle of vital functions. Protoplasm builds up every vegetable and animal fabric, it is itself devoid of discernible histological structure. It is ordinarily colorless and transparent, or nearly so, and of glairy or viscid semi-fluid consistency, as is well seen in the bodies of foraminifers, amœbæ, and other of the lowest forms of animal life. Such protoplasm (originally named sarcode) when not confined by an investing membrane, has the power of extension in any direction in the form of temporary processes capable of being withdrawn again; and it has also the characteristic property of streaming in minute masses through closed membranes without the loss of the identity of such masses. An individuated mass of protoplasm, generally of microscopic size with or without a nucleus and a wall, constitutes a cell, which may be the whole body of an organism, or the structural unit of aggregation of a multicellular animal or plant. The ovum of any creature consists of protoplasm, and all the tissues of the most complex living organisms result from the multiplication, differentiation, and specialization of such protoplasmic cell-units. The life of the organism, as a whole, consists in the continuous waste and repair of the protoplasmic material of its cells. No animal, however, can elaborate protoplasm directly from the chemical elements of that substance. The manufacture of protoplasm is a function of the vegetable kingdom. Plants make it directly from mineral compounds and from the atmosphere under the influence of the sun’s light and heat, thus becoming the store-house of food-stuff for the animal kingdom.—(See Cent. Dic. 6, p. 4799.)
Hence this substance, known in Vegetable Physiology as protoplasm, but often referred to by zoölogists as sarcode, has been appropriately designated by Professor Huxley “the physical Basis of Life.”—(W. B. Carpenter, Micros, sec. 219.)
For the whole living world, then, it results that the morphological unit—the primary and fundamental form of life—is merely an individual mass of protoplasm, in which no further structure is discernible.—(Huxley, Anat. Invert., p. 18.)
See Spencer, Principles Biology I, p. 63-67. Encyc. Brit. 19, p. 828-830; New Int. Encyc. 16, p. 471-472. Haeckel, Ev. Man, pp. 36-50; “Ovum and Amœba.”
Sec. 7. Human Body is a Compound Physical Structure Built of Cells
The human body and every organ, part and cell in it, has length, breadth, thickness and weight, like a brick or stone. So, every such body and every organ and part of it is built of material substances as completely as are the foundation, walls, roof and other parts of a brick house. The body, as a whole, and every organ and part of it, has every property and attribute of a physical structure; and all the materials of which the body is built up, except the germ-cell (or fertilized ovum), were dead matter before they were assimilated and incorporated into it. So, all the materials, of which such a body is built up, are selected, assembled, grouped together and put into position in the body in the same manner that bricks, or blocks of stone are gathered up and put into position in a building, but by different forces and other means.
But there is a marked difference between the process of building a house, engine, or other inanimate structure, on the one hand, and the body of the human embryo on the other. The wood, clay, iron and other materials used in the construction of the former are found ready to hand; and they are cut, sawed, burned, molded, or hammered, by man, into the proper size, form and condition for use in the construction of the building or machine; and are carried, by him, to the place, at which the building or machine is to be constructed. He then places these materials in such positions as to build up and complete the building or machine.