Meanwhile, let us summarize the evidence which points to the psychical unity between man and the lower life-forms. As stated on p. 187, Mr. Herbert Spencer traces the gradual evolution of consciousness from "the blurred, indeterminate feeling which responds to a single nerve pulsation or shock." There is no trace of a nervous system in the simplest organisms, but this counts for little, because there are also no traces of a mouth, or a stomach, or limbs. In these seemingly structureless creatures every part does everything. The amoeba eats and drinks, digests and excretes, manifests "irritability," that is, responds to the various stimuli of its surroundings, and multiplies, without possessing special organs for these various functions. Division of labour arises at a slightly higher stage, when rudimentary organs appear; the development of function and organ going on simultaneously. Speaking broadly, the functions of living things are threefold: they feed; they reproduce; they respond to their "environment," and it is this last-named function--communication with surroundings--which is the special work of the nervous system. It was an old Greek maxim that "a man may once say a thing as he would have said it: he cannot say it twice." This is the warrant for transferring a few sentences on the origin of the nerves from my Story of Creation. They are but a meagre abstract of Mr. Spencer's long, but luminous exposition of the subject. "As every part of an organism is made up of cells, and as the functions govern the form of the cells, the origin of nerves must be due to a modification in cell shape and arrangement, whereby certain tracts or fibres of communication between the body and its surroundings are established. "But what excited that modification? The all-surrounding medium, without which no life had been, which determined its limits, and _touches_ it at every point with its throbs and vibrations. In the beginnings of a primitive layer or skin manifested by creatures a stage above the lowest, unlikenesses would arise, and certain parts, by reason of their finer structure, would be the more readily stimulated by, and the more quickly responsive to, the ceaseless action of the surroundings, the result being that an extra sensitiveness along the lines of least resistance would be set up in those more delicate parts. These, developing, like all things else, by use, would become more and more the selected paths of the impulses, leading, as the molecular waves thrilled them, to structural changes or modification into nerve-cells, and nerve-fibres, of increasing complexity as we ascend the scale of life. The entire nervous system, with its connections; the brain and all the subtle mechanism with which it controls the body; the organs of the senses alike begin as sacs formed by infoldings of the primitive outer skin."