or even more precisely, "with the cells"; or "with the blood." Substances that are specifically elaborated for the blood would then be "out of harmony with" the cells, and conversely the substances "in harmony with" the cells are "out of harmony with" the blood, or better, with the plasma, because the components of the form elements of the blood are out of harmony with the plasma, and inversely. Products in harmony with the cells will only be in harmony with one another in so far as they belong to cells with similar functions, so that from this point of view, for instance, the specific elements of the thyroid gland must be regarded as out of harmony with those of the suprarenal bodies, and inversely. The idea of an entirely specific structure for each cell of an organ—both from the chemical and physical points of view—is based not only on the supposition that, without such a notion, the special duties and functions of the separate cells of the body would appear incomprehensible, but, above all, on the above-mentioned fact that definite secretions given off by particular organs act constantly and only upon cells of a definite system. This implies that the cells in question must have a structure which distinguishes them sharply from all other kinds of cells.
The view that each animal species is capable of building up complicated compounds of peculiar
