=2. Would the Mental Deficiency respond to Medical Treatment?=--Cannot the doctor prescribe something to cure the mental deficiency or want of balance? Let us give some consideration to this question. Medicines act either upon the symptoms of a disease, or upon the organic changes which produce them, or, lastly, upon the very causes of such organic changes. Quinine, for example, has a selective action on the parasites of malaria; mercury produces an undoubted effect upon syphilitic growths; treatment by cold baths keeps the temperature of typhoid fever below a certain level during the whole of the illness. Cannot analogous results be hoped for in mental deficiency? A brief résumé of what we know concerning the causes of mental deficiency and the anatomical lesions which accompany it will determine our answer. The dominant etiological feature is that mental deficiency and want of balance depend upon hereditary conditions, or conditions acquired in the earliest stages of development. By hereditary conditions must be understood strictly those which result from alterations in the germ cells of the parents. An intoxication alone seems capable of exercising upon the latter a sufficiently general action to reach the germ cells, and by far the most frequent poison is alcohol. By acquired conditions must be understood the results of diseases of the foetus or of infancy, and especially the cerebral complications of the infectious fevers--_e.g._, meningitis in the course of an eruptive fever. In all such cases, with rare exceptions to be mentioned immediately, by the time the mental deficiency is discovered, its causes are no longer active, and consequently cannot be affected by medical intervention. The statements we have just made with regard to the causes of mental deficiency lead to some practical conclusions. The ultimate evolution of the congenital cases differs from that of acquired cases, and this renders a study of the early history of the child important. If the development of the child has been normal at first, and has then been abruptly interrupted, for example, by an attack of meningitis, of which we can obtain by inquiry a definite history, the prognosis is not good. For it is a well-recognised fact that cases of acquired mental deficiency are not likely to make a fresh start. If we were hesitating whether to send an imbecile child to an asylum or to put him in a class for mental defectives, a history like the above would lead us to give the preference to the asylum; but let us say once more, we do not find here an indication for treatment. As to the changes which are found post-mortem, these are manifold and of an unalterable kind. They are as follows: