ABSTRACT
We have seen that physiologists recognise only motor and sensory centres ; but it is evident that, behind these centres, there lie also all the functions which constitute mental phenomena. It has also been shown that the study of the microscopical appearance of the brain has produced mag nificent results, but has failed, so far, to explain the nature of mental activities and disorders of the mind. Chemical and glandular theories, too, have thrown some light on the special mental disorders which are caused by such agencies, but do not touch the great problems concerning mind and brain. Insanity will never be explained until we admit that the primary psychical activities are dependent on definite and separate instruments. In my opinion, it is because of the non-recognition of the principle of localisation of mental functions that so little progress has been made, both in the study and treatment of brain disease and mental disorder. Most insanities, as I have pointed out, are held to be purely functional, and others are assumed to involve the entire brain ; consequently, clinical observation is believed to be oflittle practical use, even where opportunities are given.
