there seems to be an arrest of the processes of association. Such are, for example, all hypnotic states. The analogy to the forms of transmission of physical energy is striking, and has led Prof. James to conjecture that the higher development of the few ideas remaining is in some way a compensation for the arrest of association. "If," he says, "we regard association paths as paths of drainage, then the shutting off of one after another of them as the cerebral paralysis advances ought to act like the plugging of a hole in the bottom of a pail, and make the activity more intense in those systems of cells which retain any activity at all." Prof. James then quotes from Taine a vivid description of the rise in the level of the idea trains as the association paths are closed by sleep. "All external sensations are gradually effaced, or cease at any rate to be remarked; the internal images, on the other hand, feeble and rapid during the state of complete wakefulness, become intense, distinct, colored, steady, and lasting: there is a sort of ecstasy, accompanied by a sense of expansion and comfort. Architecture, landscapes, moving figures, pass slowly by, and sometimes remain with incomparable clearness of form and fullness of being; sleep comes on, and I know no more of the real world I am in. Many times, like M. Maury, I have caused myself to be gently roused at different moments of this state, and have thus been able to mark its characters. The intense image which seems an external object is but a more forcible continuation of the feeble image which an instant before I recognized as internal; some scrap of a forest, some house, some person which I vaguely imagined on closing my eyes has in a minute become present to me with full bodily details, so as to change into a complete hallucination. Then, waking up on a hand touching me, I feel the figure decay, lose color, and evaporate; what had appeared a substance is reduced to a shadow. In such a case I have often seen, for a passing moment, the image grow pale, waste away, and evaporate; sometimes on opening the eyes a fragment of landscape or the skirt of a dress appears still to float over the fire-irons or the black hearth."
In the three types which I have been discussing, the mental state was present as a thought before being externalized as a hallucination, and for many reasons hallucinations of this type are the most instructive. But very often the hallucination is not only not a mere externalization of a thought already present, but has no apparent connection with anything of which the patient is at the time thinking. Hence the theory of development needs to be supplemented by other considerations, and one may draw them from either of two quite different, although I think not inconsistent, points of view. In the first place, one may suppose that the hallucination is sometimes initiated from without, through some