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This purports to be a learned consideration of the organs of sex and the cells producing offspring with especial reference to sex determination. The author describes a part of spermatozoa which others have not seen, the "sex membrane." This, he asserts, holds the nucleus or head of the spermatozoon as if in a cup. It covers more or less of the head according as the spermatozoon is young. or of hours or days of age. When the sex-membrane covers less than one-half of the nucleus of the spermatozoon "the tail and all enter into the cytoplasm of the ovum and a male is produced." When, however, the sex membrane covers more than one-half of the nucleus of the spermatozoon it becomes detached when it passes through the cytoplasm of the ovum and only the nucleus enters the latter. Under these circumstances a female is produced. The author gives instructions as to
The Key to Sex Control. JAMA. 1912;LVIII(21):1636. doi:10.1001/jama.1912.04260050310040