Clown: … Nay, I'll never believe a madman till I see his brains.

Substantial contributions to clinical medicine have come from the many accounts of abnormalities in the brains of mental defectives, our knowledge of certain conditions such as epiloia, amaurotic family idiocy and microcephaly being largely based on them. But, in the main, these reports have concerned cases selected for some special interest and few workers have attempted to relate morbid-anatomical changes to the general problem of mental deficiency. The most complete description, chiefly histological, of lesions in the brains of idiots is that of Schob (1930), who summarized in his valuable contribution the wide experience of German neuropathologists. The brains of 120 unselected cases were later studied by Berry (1938), the results being published in an atlas illustrating, case by case, the differences between normal and mentally defective individuals. More recently, Christensen and Vestergaard (1949) presented a short account of a routine autopsy series of 46 mental defectives, finding some structural abnormality in every one of these cases. Other researches covered more restricted aspects of the problem and some of these will be referred to below.