=Imbecility= is a form of mental defect not usually congenital, but commencing in infancy or in early life. The line of demarcation between the imbecile and the idiot may be found in the possession by the former of the faculty of speech, in distinction from the mere parrot-like utterance of a few words which can be taught the idiot. Imbecility may be intellectual, moral, or general. Questions frequently arise as to their responsibility for actions done by them, or as to their ability to manage their own affairs. =Cretinism= is a form of amentia, which is endemic in certain districts, especially in some of the valleys of Switzerland, Savoy, and France. The malady is not congenital, but its symptoms usually appear within a few months of birth. The characteristics of this form of idiocy are an enlarged thyroid gland constituting a goitre or bronchocele, a high-arched palate, dwarfed stature, squinting eyes, sallow complexion, small legs, conical head, large mouth, and indistinct speech. =Feeble-Minded.=--These are persons who are capable of earning a living under favourable circumstances, but are incapable, from mental defect which has existed from birth or from an early age, of (a) competing on equal terms with their normal fellows, or (b) of managing themselves and their affairs with ordinary prudence. Feeble-mindedness may affect the moral nature only, rendering the person selfish, untruthful, obscene, or unemployable. The Act of 1899 controls feeble-minded children; many such become paupers, criminals, prostitutes, etc. =Mental Deficiency and Lunacy Act, 1913.=--Those included under this Act are idiots, imbeciles, feeble-minded persons, and moral imbeciles. The parents or guardians of such children between the ages of five and sixteen years must provide for them education and proper care. If they are unable to do so, the School Boards or Parish Councils must do so. XLII.--DEMENTIA: ACUTE, CHRONIC, SENILE, AND PARALYTIC In dementia the mental aberration does not occur until the mind has become fully developed, thus differing from amentia, which is congenital or comes on very early in life. =Acute Dementia.=--This is a condition of profound melancholy or stupor, which arises from sudden mental shock, the mind being, as it were, arrested and fixed in abstraction on the event. =Chronic Dementia= is generally caused by the gradual action on the mind of grief or anxiety, by severe pain, mania, apoplexy, paralysis, or repeated attacks of epilepsy. =Senile Dementia= is a form which is incidental to aged persons, and commences gradually with such symptoms as loss of memory for recent events, dulness of perception, and inability to fix the attention. Later on the reasoning powers begin to fail, and finally, memory, reason, and power of attention, are quite lost, the muscular power and force remaining intact. In the last stage there is simply bare physical existence.