In four previous publications1 one of us (C. E. B.) has accumulated evidence that the so-called mongoloid deficiency is associated with an endocrine disorder. It has been demonstrated that the physical appearance in this condition is due to a developmental failure in growth, especially of the skull. Further studies are under way to determine how far the mental deficiency of this condition depends on the same factors.
The conception of an endocrine disorder as a primary factor differs from the opinions of most contemporary writers, who regard mongolism as a pathologic mutation due to an unknown factor in the germ cells or as an atavistic regression.
The latter view is emphasized by Down2 and especially by Crookshank,3 who consider mongolism as a racial regression. Our anatomic studies indicate that there is no relation between mongoloid deficiency and the Mongolian race. However, in order to approach the problem