If the second alternative—specific differentiated residua—be the medium by which experiences are conserved, then the residua must be either specific psychological states, i.e., the original psychological experience itself as such; or neural residua (or dispositions) such as when excited are ordinarily correlated with a conscious memory. In either case the medium would be such as to permit of the experiences manifesting themselves, while so conserved outside of the personal consciousness, as a very specific secondary process, not only reproducing the original experience as memory, but elaborating the same and exhibiting imagination, reasoning, volition, feeling, etc. Unless the doctrine of the undifferentiated Psyche be accepted it is difficult to conceive of any other mode in which conservation can be effected so as to permit of the phenomena of memory outside of consciousness. =Conservation considered as psychological residua.=—It is hypothetically possible that our thoughts and other mental experiences after they have passed out of mind, out of our awareness of the moment, may continue their psychological existence as such although we are not aware of them. Such an hypothesis derives support from the fact that researches of recent years in abnormal psychology have given convincing evidence that an idea, under certain conditions, after it has passed out of our awareness may still from time to time take on another sort of existence, _one in which it still remains an idea, although our personal consciousness of the moment is not aware of it_. A coconscious idea, it may be called. More than this, in absent-mindedness, in states of abstraction, in artificial conditions as typified in automatic writing, and particularly in pathological conditions (hysteria), it has been fairly demonstrated, as I think we are entitled to assert, that coconscious ideas in the form of sensations, perceptions, thoughts, even large systems of ideas, may function and pursue autonomous and contemporaneous activity outside of the various systems of ideas which make up the personal consciousness. It usually is not possible for the individual to bring such ideas within the focus of his awareness. Therefore, there necessarily results a doubling of consciousness,—two consciousnesses, one of which is the personal consciousness and the other a coconsciousness. These phenomena need to be studied by themselves. We shall consider them here only so far as they bear on the problem of conscious memory. Observation has shown that among ideas of this kind it often happens that many are memories, reproductions of ideas that once belonged to the personal consciousness. Hence, on first thought, it seems plausible that conservation might be effected by the content of any moment’s consciousness becoming _coconscious_ after the ideas have passed out of awareness. According to such an hypothesis all the conscious experiences of our lives, that are conserved, would form a