Integration of Raw Materials.

Every group of animals in the higher ranks has its own entailed property of innate reflexes, for example, the reflexes which subserve the reflex functions of the cord: those of locomo­tion, muscular and vascular tone, micturi­tion, defæca­tion, impregna­tion and parturi­tion. These exist in an animal of the spinal level whether or not it remains purely aquatic, partly aquatic, partly terrestrial, arboreal or terrestrial. As the progressive groups ascend the ladder of life they add to this inalienable heritage, gained we need not here ask how, fresh reflex-arcs by response to new initial stimuli, forging them by the incident of use. So, the original acquirements in the past levels serve as starting points for raising the degree of their nervous integra­tion with growing control over their environments. The long story from the simple central nervous system of a fish, with a few or no associa­tion-areas, to that of man with his extensive frontal, parietal, parieto-occipital associa­tion-areas, could never be deciphered, even with the light of the laws of genetics turned on full, without a protracted process of construc­tion of fresh arcs. A common illustra­tion of such a series of changes and results may be seen in the building of a house. Bricks, founda­tion-stones, walls and a roof may serve some of the elementary requirements of a house and much less than these were of use to early man for his shelter. Without them we cannot call any structure a modern house; but also without floors, staircases, windows, chimneys, division into rooms, some degree of decora­tion by paint or paper, and a supply of water, we should refuse in these days the name of house to that rough structure, apart from beauty of design, decora­tion, within and without, and some addition of modern appliances of comfort and convenience. In the history of house-building the stages of supply of raw materials, adapta­tion to needs guided by selection, initia­tion, trial and error have their counterpart in the construc­tion of higher animals.