parts of the nervous system morbidly affected being exceedingly different.
I have so far almost ignored the distinction between nervous states and mental states. Now, if the case of insanity be considered as a series of mental phenomena only, it would be absurd to compare or even to contrast it with progressive muscular atrophy, which is a series of physical phenomena only. But no difficulty can arise if it be understood that insanity, or "disease of the mind," is with medical men disease of the highest nervous centers revealing itself in a series of mental phenomena. We compare and contrast disease of the highest centers with disease of some anterior horns (some lowest centers) revealing itself in atrophy of certain muscles. But, acknowledging this, it may be said that the two things are so exceedingly different that it is frivolous to compare or even to contrast them on any basis. Yet, no one denies that each is a morbid affection of the central nervous system; this being granted, the rejoinder to those who insist on the extreme unlikeness is that the lesion in one is at the very bottom, in the other at the very top, of the central nervous system; two lesions can not possibly be farther apart in the central nervous system. Still it may be said that classification, on the principle of dissolution, if true, is of no value; that it is of no use making an orderly ascending series from progressive muscular atrophy to insanity—of no use showing that progressive muscular atrophy is reduction to a more automatic condition in a small corner on the lowest level, that hemiplegia is such reduction on a larger scale higher up, and that insanity is such a reduction on the topmost level, and on the largest scale—that even if this kind of work could be thoroughly well done it is not worth any one's while to do it. I grant that such a classification is not of direct value, but yet I think it of much indirect value for clinical purposes. We require in our profession two kinds of classification. The use of two classifications may be easily illustrated. There is a classification, or strictly an arrangement, of plants by the farmer for practical purposes, and there is a classification of plants by the botanist for the advancement of biology. I submit that there is no more incongruity in classing together progressive muscular atrophy and insanity upon the basis mentioned than there is in classifying the bamboo with common grass, or the hart's-tongue with the tree-fern in a botanist's garden. Such kind of classification of plants would be absurd in a farm or kitchen-garden, and so would a classification of diseases of the nervous system upon the principle of dissolution be absurd in an asylum or in the wards of a hospital. I know of no other basis on which cases of insanity, diseases of the highest centers, can be studied comparatively with non-mental diseases of the nervous system—diseases of lower centers.
I next speak of different depths of dissolution. The deeper the dissolution the shallower the level of evolution remaining. In hemi-
