In the “irritability” of the sundew, Venus’s fly-trap, and other sensitive plants, still more so in subtile and hidden movements in plant-cells, we have actions corresponding to those called “reflex” in animals, as the contraction of the shapeless amœba when touched, or the involuntary closing of our eyelid when the eye is threatened, or the drawing back of one’s feet when tickled. The filament in the amœba which transmits the impulsion, causing it to contract differs only in one degree from the sensory nerves in ourselves which transmit the impression to the motor nerves, causing the muscles to act; and since there is every reason for referring the contractile actions of plants--_i. e._, their movements in obedience to stimulus--to like causes, the germs of a nervous system must be conceded to them. The minute observations of Mr. Darwin and his son into the large class of quasi-animal movements common to wellnigh all vegetable life go far to confirm this. The highly sensitive tip of the slowly revolving root, in directing the movements of the adjoining parts, transmitting sensation from cell to cell, “acts like the brain of one of the lower animals; the brain being seated within the anterior end of the body, receiving impressions from the sense organs and directing the several movements.” In these and kindred vital processes, in the so-called sleep of leaves, and the opening and closing of flowers, both regulated by the amount of light, apparently acting on them as it acts on our nervous system; in the detection of subtle differences in light, which escape the human eye, by plants; in their general sensitiveness to external influences, even in the diseases which attack them, the study of which Sir James Paget has commended to pathologists, we have the rudiments of attributes and powers which reach their full development in the higher animals, and therefore a series of fundamental correspondences between plant and animal which point to the merging of their apparent differences in one community of origin. In fine, that which was once thought special to one is found to be common to both, and to this there is no exception. Not only is there correspondence in external form in the lower life groups, but, fundamentally, plants and animals are alike in internal structure and in the discharge of the mysterious process of nutrition (although this forms a convenient line of separation) and of reproduction. All, from the lowest to the highest, have their unity and kinship in ancestral life which was neither plant nor animal.