The reservations of the public health authority could not check further developments, however. The National Socialist movement was becoming stronger, and in it were the most eager proponents of the Lex Zwickau principles. Professor of medicine Fritz Lenz, for example, expressed his concern for the Germans "without space . . . the at least 20 million capable persons," for whom he wished to find room within Germany's borders. Lenz recommended that more space could be found by reducing the population through the "sterilization of all the unfit and inferior." Lenz believed about 30 percent of the population to be bearers of unsound hereditary traits who should have no right to reproduce.
Among German teachers of deaf children, growing support for racial hygiene and thus for sterilization was apparent in the 1920s. Teachers subscribed to the views of authors Bauer, Fischer, and Lenz in Outline of Human Genetics and Racial Hygiene (Grundriss der menschlichen Erblichkeitslehre und Rassenhygiene), which was published in two volumes (Vol. 1, Human Genetics; Vol. 2, Human Selection and Racial Hygiene). A book reviewer for the Journal for Deaf Education, a teacher identified only by the letters W. J., noted in 1926 that Lenz had devoted a chapter to hereditary causes of deafness and gave great currency to the term "hereditary." On the whole, he "especially wished to recommend" the first volume. He also praised the second volume as "quite interesting," for "here the theme and objective of the entire work are revealed to the reader: an earnest and thoroughly justified exhortation to racial hygiene."
Writing in the same journal, teacher A. Abend had asked in 1925 , "What does racial hygiene have to say to the teacher of the deaf?" He insisted that all deaf educational efforts were failures, and that "the schooling of the deaf constitutes contra-selection." While he agreed that persons deafened from "accident or illness are genotypically [hereditarily] sound," persons with hereditary deafness should not be allowed to marry. His concluding thesis marked a strong endorsement of racial hygiene programs applied to deaf people. "The severely, genotypically degenerate deaf constitute a burden on the people. The people's need can demand the prevention of their reproduction."
Abend's essay represented a change of course for German deaf education that would last until 1945. His central assertion, that "deafness represents nothing desirable, nothing worth striving for," marks the turning point. Abend reinforced his statement with an admonition to deaf education: "As teachers of the deaf, we too must adopt this [the eugenicist's] position."
In 1929, teacher P. Schumann wrote about the causes of deafness and made clear that he, too, judged eugenics favorably. He granted heredity "a very important role" in deafness, and he noted with regret "that the influence of heredity is often underestimated." On the other hand, he warned against exaggerating the heritability of deafness, "lest there arise a demand for the sterilization of all the constitutionally deaf." In the concluding part of his essay, Schumann returned to his approving assessment that "direct genetic transmission . . . to a certain and not inconsiderable extent is to be assumed as the cause of deafness." Since genetic inheritance was "not, however, the rule," Schumann suggested that "in general, legal intervention would not be useful relative to the elimination of reproduction among the deaf and dumb."