THE PATHOLOGIC evidence presented in this paper tests a hypothesis that whatever the cause of mongolism may be1 the condition originates between the sixth and the ninth week of fetal life. This evidence is based on the established features of the disorder supplemented by observations from the protocols of fifty autopsies performed during the past twenty-five years at the Children's Hospital in Boston.
The pathology of mongolism has been extensively studied by Brousseau and Brainerd,1a Benda1b and many others.2 These investigations show no anatomic system to escape from at least occasional anomalous development.
ESTABLISHED ANATOMIC FEATURES
Skull.—Bullard2g studied roentgenograms of 25 mongoloid skulls thirty-five years ago and concluded that "the cranium is not only so small as to be technically microcephalic, but is brachycephalic, i.e., the transverse diameter is excessively large in proportion to the shortened anteroposterior diameter. It immediately suggests that this condition