Hemihypertrophy and Mental Defect

Anomalies of anatomic development and mental defect are often found in close association. A noteworthy example of this fact came to the writer's attention in 1913. A boy, then 13 years of age, was presented for mental examination. He was found to be mentally deficient. A physical inspection of the whole body of the boy showed this deficiency to be associated with one of the most remarkable of developmental anomalies; namely, total unilateral hypertrophy. This anomaly is considered to be one of the rarest in the domain of medicine. Marked cases are indeed extremely few as a survey of the literature will reveal; but how frequent mild, unrecognized cases are, remains to be determined. It is because hemihypertrophy presents a startling, though legitimate, deviation from an almost universal law of development that it constitutes a subject rich in suggestion—and perplexity. A brief description of the physical and mental characteristics of