cnemius muscle attached, when it is stimulated by the electrical current. And as to a science of nerve-physiology, which shall apply with any accuracy of detail to the variety of cerebral processes concerned in human thoughts and feelings — well, it is hard to measure our present remoteness from such a science.
I have already said that Professor James furnishes only two short chapters, which even attempt a summary of the results of modern investigation respecting those "conditions" of mental phenomena which, according to his conception, are the only conditions admitting of scientific treatment. His chapter "On the Functions of the Brain" is on the whole excellent. It is written with fulness of information brought well down to the present time. Yet it contains statements which would by no means command universal acceptance by expert students of the subject. For example, it will scarcely do to say that Broca's convolution is the seat of injury, without exception, in all cases of pure motor aphasia (I, p. 38 f.). The conclusion of the present state of knowledge on the general subject is, that we are fairly certain what parts of the cerebral hemispheres are somehow concerned in the intelligent management of the limbs; less certain, what have to do with "psychical vision"; less certain still, precisely what and how many have to do with the expression and interpretation of spoken or written language ; and very uncertain as to where are the so-called "centres" of the other sensory-motor forms of mental life. But as to the localization of any of the "higher" forms or factors of thoughts and feelings, we are almost totally in the dark. Nor should we know what to do with such centres, if we could succeed in getting any clear trace of their existence.
Nevertheless, in the direction of locating centres, cerebral physiology is making rapid and real progress. It seems strange, therefore, that Professor James makes little or no attempt to work out in detail a theory of the empirical conditions of the phenomena of mental life, on the basis of this chapter. Why does he not tell us, for example, precisely in what cerebral centres the consciousness of self, the perception of time, the perception of space, the instinctive beliefs, and the necessary truths, have
