circulation, then we must expect troubles of all kinds. Such a case may arise, for instance, when certain cells cannot complete a decomposition that they have initiated, owing to the absence of the necessary agent, i.e., the ferment; so that the incomplete action of a particular organ may be the cause of numerous disturbances of every kind. If continuity of function be broken but once, then one disturbance, like an avalanche, is followed by another. It is true that the organism defends itself in such a case. It produces compensatory activities and tries to adapt itself to the new conditions, often succeeding in a most amazing fashion, and repairing the damage for a long period of time. Pathology supplies us every day with examples of this kind. The study of cellular functions under variable conditions is one of the most attractive that we know. Experimental pathology is a field which will be of undoubted importance for the whole of physiology, and to an extent as yet unrealized.
Thus all observations on the structure and metabolism of the individual cells of the body lead us, in the most unequivocal manner, to the conclusion that within a given organism large aggregates of cells work together harmoniouslv for the benefit of the whole. Complete harmony of relations is guaranteed—let us emphasize the fact once more—by
