An expression that one often hears from the physician is that some special condition or manifestation is constitutional, in the sense of fundamental in nature, instead of being the result of some more or less immediate environmental occurrence. The suggestion has come to me that the members of an organization such as the American Pediatric Society, devoted primarily to the ills of childhood, might be interested in the biologist's conception of this fundamental nature of the child.
Since living organisms invariably arise as the offspring of preexisting living organisms of the same kind, it is obvious that if a particular living creature is human, it is because his ancestors were human. He is Anglo-Saxon or Scandinavian or Mongolian because of parentage, and furthermore, he has many characteristics of mind and body that are recognized as family traits. Not only general features and structures, but minute physical defects, mental peculiarities and