dialysation process, as well as in the optical method, human organs may sometimes be replaced by those of animals, might easily lead one to argue against the existence of specifically constructed cell units, as well as of the ferments that act on them.
A special place is occupied, at least qualitatively, by all those substances which, like the units of the different organic nutritive and tissue materials—as well as the inorganic constituents, the salts, water, &c.—exhibit no specific structure, and which are common to the most different kinds of cells, as well as to the blood and lymph, as intermediate and final products. In this case disturbances can only be caused by quantities. Rapid secretion, or synthetic or analytic processes, may in such cases act in a regulating manner and again restore normal conditions. All substances, however, which have a specific structure, are peculiar either to the blood or else to specific cells. From this point of view we must consider substances, which leave the cell and pass into the blood in a state of insufficient decomposition, as being out of harmony with the blood, or rather with the plasma; and, inversely, disturbances would certainly occur in the metabolism of certain cells, if, for instance, the insufficiently decomposed constituents of muscle cells were to penetrate the cells of the kidneys. The units of the muscle cells are out of harmony with the cells of the kidneys, and only a
