The acardiac monster.

Two cases of acardiac fetuses are presented. Pathological data in 61 cases are tabulated. Cliassification, terminology and patho-physiological findings are discussed. The Acardiac Monster is a form of monozygotic multiple gestation lacking a physiological heart and resulting in a bizarre fetal malformation which is sustained in utero by parasitic anastomoses to the circulation of a normal twin fetus. The precise etiology of this phenomenon is still obscure and suggestions are made for the future evaluation of the acardiac fetus.