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stunted brain, which is incapable of development. Here the chief link is inaccessible to the weapons we at present possess, and we know of no means by which the defect can be remedied. Treatment must be limited to influencing, so far as lies in our power, the minor links of the chain with the object of ameliorating the patient's symptoms. This is the treatment always adopted in dealing with cases of this type, and forms the basis of the well-known methods of "training" now in use for the mentally deficient. In another type bodily changes, especially disease of the brain, constitute the most important factor, and a chain of causes exists which may be represented as follows:
In this type, to which certain forms of insanity such as general paralysis belong, the brain disease is vastly the most important causal element, and it is to this that our attempts at treatment must be directed. In the symptoms shown by the patient mental changes may bulk largely, but in the chain of cause and effect they are links of only secondary importance, and it is the constitution of this chain which is of vital concern to the problem of treatment.
In a third type both physiological and mental factors seem to play an active part, and we are uncertain in the present state of our knowledge as to their relative importance. The chain here may be represented as in the accompanying diagram, where
