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July 7, 1923


JAMA. 1923;81(1):55-57. doi:10.1001/jama.1923.02650010059022

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June 2, 1923.

Experimental Modification of the Ratio of the Sexes in Animals  In many animals there is a persistent preponderance of one sex over the other. For instance, in the case of the pig there are 117 males to 100 females; in the hawk family there are only 87 males to 100 females. This ratio, which, in the various species of plants and animals, presents an approximately constant value, may be modified by experimental intervention. Dr. Agnes Blum has for some time been conducting, experiments of this kind, with white mice, which possess great theoretical value. In white mice there are normally only 80 males to 100 females. These proportions may be considerably modified by the effect of chemical substances on the organism. The injection of certain definite quantities of alcohol caused the males to increase from 80 to 122. Also yohimbin raised the number of males from 80

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