Mr. Darwin appears, by "Natural Selection," to destroy the reality of species, and by Pangenesis that of the individual. Mr. Lewes observes[227] of the individual that "This whole is only a subjective conception which summarizes the parts, and that in point of fact it is the parts which {217} are reproduced." But the parts are also, from the same point of view, merely subjective until we come to the absolute organic atoms. These atoms, on the other hand, are utterly invisible, intangible; indeed, in the words of Mr. Darwin, inconceivable. Thus, then, it results from the theories in question, that the organic world is reduced to utter unreality as regards all that can be perceived by the senses or distinctly imagined by the mind; while the only reality consists of the invisible, the insensible, the inconceivable; in other words, nothing is known that really is, and only the nonexistent can be known. A somewhat paradoxical outcome of the speculations of those who profess to rely exclusively on the testimony of sense. "_Les extremes se touchent_," and extreme sensationalism shakes hands with the "das seyn ist das nichts" of Hegel. Altogether the hypothesis of Pangenesis seems to be little, if at all, superior to anterior hypotheses of a more or less similar nature. Apart from the atoms of Democritus, and apart also from the speculations of mediaeval writers, the molecules of Bonnet and of Buffon almost anticipated the hypothesis of Pangenesis. According to the last-named author,[228] organic particles from every part of the body assemble in the sexual secretions, and by their union build up the embryo, each particle taking its due place, and occupying in the offspring a similar position to that which it occupied in the parents. In 1849 Professor Owen, in his treatise on "Parthenogenesis," put forward another conception. According to this, the cells resulting from the subdivision of the germ-cell preserve their developmental force, unless employed in building up definite organic structures. In certain creatures, and in certain parts of other creatures, germ-cells unused are stored up, and by their agency lost limbs and {218} other mutilations are repaired. Such unused products of the germ-cell are also supposed to become located in the generative products. According to Mr. Herbert Spencer, in his "Principles of Biology," each living organism consists of certain so-called "physiological units." Each of these units has an innate power and capacity, by which it tends to build up and reproduce the entire organism of which it forms a part, unless in the meantime its force is exhausted by its taking part in the production of some distinct and definite tissue--a condition somewhat similar to that conceived by Professor Owen.