organism of the mother. The blood probably receives substances—perhaps also secretions—which are out of harmony with the plasma, and remain so; and the time is too short for the blood to accustom itself entirely to these new kinds of substances. The placenta, according to this point of view, together with the fœtus, never settles down completely within the organism of the mother. With the expulsion of the placenta, in which process, again, ferments probably play a preparatory part, the ferments which are directed against its albumen disappear fairly quickly. It is, of course, quite possible that these placentally active ferments are conditioned by many different forces.
The view we have just discussed gives us an opportunity of demonstrating the initiation of the function of a particular organ. Were an organ to suddenly take up a particular function at a particular moment—say the delivery of a particular secretion—then it is quite conceivable that its activities would, at first, be disharmonious with the plasma. We might possibly expect something of this kind from the sexual glands at the onset of puberty; but experiments carried on in this direction upon animals in heat have not as yet given any certain result. On the other hand, the cessation of the functions of a particular organ might lead to the appearance of substances out of harmony with the blood; for these functions do not cease suddenly, and it may be that their gradual dis-
