LUCID INTERVAL. What intermission is to certain fevers, a lucid interval is to certain forms of mental disease. Those forms in which it occurs are charactelized by exaltation or perversion, and not by impairment of the faculties or feelings. There may thus be a cessation or suspension of the fury in mania; there cannot be repair or enlight enment of the obscurity in idiocy or senile dementia. It inay consist in the mere sub stitution of clearness and calmness for violence and confusion; in the occasional recognition of his actual condition and external relations by the lunatic; or in the re-establishment of intelligence and natural feeling so perfect and complete as to differ from sanity solely in the want of permanence. The duration is likewise sometinies so considerable and regular as to divide the mental and moral life of the individual into two halves. It has been believed that even in such cases the interval is a part or link of the disease, and that there invariably exists an under-current of unsoundness. It is
found to be extremely difficult to distinguish this state from real and tnistworthy restoration to reason, except by reference to duration. Practically and leaally, these conditions have been held to be identical. A will executed during a lucrd interval, although that was extremely transitory, and although the testatrix unloosed the straps by which ber hands had been confined, in order to execute the document, has been held to be valid; all that appears to be required, under such circumstances, is to prove that the conduct of the individual bore the aspect of rationality and health. It has been observed that, immediately before death, a small proportion of tin insane regain lucidity, and, after years of extravagance and absurdity, die in possession of comparative sense and serenity. This change is supposed 1.0 depend upon the failing powers of the circu lation.—Burrows, On Insanity ; Shelford, Oa Law of Lunatics, p. 289.