THE medical literature of the past five decades is replete with statements that multiple congenital malformations are always and necessarily due to changes in the germ plasm. In one sense such statements imply that multiple congenital anomalies are always hereditary and, when so interpreted, they may lead to untoward consequences. It is of considerable practical importance for the bearer of congenital defects, as well as for other members of his family, to know whether or not his defects are heritable. The question is also of concern to those who are sincerely interested in eugenics from the standpoint of public health. The importance of this point is illustrated by a certain sterilization law which was enforced for some time upon 80 million people and which stated: "Persons who show simultaneous appearance of different severe, or even mild physical endogenous malformations . . . . should be sterilized, if in the blood relationship any severe or mild endogenous malformations have been shown to occur in at least one person singly, bilaterally or in aggregation." The opinion that multiple congenital malformations are necessarily hereditary dates back to the time when amniotic bands were considered the only extrinsic cause of malformations. Since it was difficult to explain familial, symmetrical, systemic or internal malformations in terms of amniotic bands; and, since no other environmental mechanisms capable of producing such malformations had been recognized, these anomalies were attributed to changes in the germ plasm. This is expressed in a textbook on "Human Heredity" in the following words:
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