In dealing with nervous exhaustion produced by the infectious diseases, the dangers of the convalescent period are not sufficiently taken into account. Parents are but too apt from mistaken motives of economy to dismiss the physician at the onset of convalescence. It is precisely at this period that the system hovers between permanent systemic defect and recovery. Proper diet and proper training at this time will often prevent the checking of puberty development, and hence a breakdown under the stress of that period. The same is true of the convalescent period from such diseases in adults. Many a mother has thus injured her constitution and given birth to degenerate children in marked contrast with the normality of the children born before. Frequently efforts are unsuccessful either because the family physician and the educator have no time to superintend treatment, or because they are unable, for many reasons, to individualise treatment properly. Hence the high value of well-organised special boarding schools for the degenerate. The special aim, says Koch, is to teach the patient to govern himself, to repose confidence in himself. To reach this end a great deal is required of him who undertakes the treatment. He has to exercise himself with patience. He must know how to divide the time for work and the time for rest. For many of these ill-balanced subjects variety is wanted as well in physical work as mental training. Those charged with these remedies, exercising good judgment, are soon able to distinguish the more favourable cases from the more difficult. They can soon say that a favourable remedy for the one may be noxious for another, and _vice versâ_. Tonics, spirits, cold baths, &c., and even hypnotism may be tried, but great caution is to be exercised, and these remedies should never be employed except by prescription of physicians. Even subjects of congenital mental instability suffering from obsession (imperative ideas) without delusions are not inaccessible to treatment. In these cases naturally the most important part belongs to the medical treatment as in most mental cases. The more serious cases, dating from the first youth and aggravated in proportion to the age, are not to be completely cured. The progressive evolution can be stopped and patients ameliorated in such a way that improvement makes their life bearable.