. The Mechanism of Mendelian heredity. Mendel's law; Heredity; Chromosomes. 112 SEX INHERITANCE testes in the male is presumably the essential condition that brings about the development of horns in that sex when only one gene for horns is present. We have already seen that the castrated Merino ram fails to develop horns. In this case, then, some substance is produced by the testes that causes horns to develop. In another race, in which both sexes are horned, but the horns of the male are larger than those of the female, castration limits the development of the horns to the condition. Fig. 3GD
. The Mechanism of Mendelian heredity. Mendel's law; Heredity; Chromosomes. 112 SEX INHERITANCE testes in the male is presumably the essential condition that brings about the development of horns in that sex when only one gene for horns is present. We have already seen that the castrated Merino ram fails to develop horns. In this case, then, some substance is produced by the testes that causes horns to develop. In another race, in which both sexes are horned, but the horns of the male are larger than those of the female, castration limits the development of the horns to the condition. Fig. 3GD.—Eusehistus. To left, E variolarins male; to right, E servus male. (After Foot and Strobcll.) shown by the females. In this race the testes cause the horns to develop to a higher stage than that shown by the female. The second case is that of the two species of bugs (Fig. 36 D) viz. Euchistus variolarius and E. servus. The former has, in the male, a black spot on the ventral surface of the end of the abdomen, which is lacking in the male of the other species. Among the females of both species the spot is lacking. Foot and Strobell have shown that a. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Morgan, Thomas Hunt, 1866-1945. New York, H. Holt
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Keywords: ., bookcentury1900, bookdecade1920, bookpublishernewyo, bookyear1922
