Pedigrees of Negro families / by R. Ruggles Gates.

  • Reginald Ruggles Gates
Date:
1949
Catalogue details

Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: Pedigrees of Negro families / by R. Ruggles Gates. Source: Wellcome Collection.

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    spots on the body, especially the arms, because of which the males were nicknamed “the spotted.” In III.3 there were spots on the leg, and in III.6 one on the lower abdomen. Some males had these spots without the white forelock, while one female had the white forelock but no spots on the skin. The evidence is not sufficient to determine whether one gene or two are involved. It is possible that this mild form of piebaldism is independent of the gene for white forelock. In another family (Fig. 45) there are four cases of white forelock in three generations. The white patch of hair is on the “foremost part of the head in the shape of an arrow.” It is about 2 inches long and inches wide, and the skin beneath the forelock is also devoid of pigmentation. But there are no other spots on the skin, and the hair is black and does not turn gray early. There are no records of the ancestry in this family beyond the grand parents. It is well known that in some families a patch of white or differ ent colored hair is found on some other part of the head. In Fig. 46 two brothers had a patch of gray hair on the lower left mastoid re gion, but the one who had children failed to transmit the condition to his descendants. The compiler of this pedigree points out that the variations in colored families, which are of course much wider than in white families because they include the ranges of variation of two races, have often caused family disturbance, because the parents failed to realize that some wide variation in a child was the result of genetic segregation and was not due to false paternity. Early graying in a Negro family living in Texas is shown in Fig. 47. There were 12 cases (8d% 4$) in four generations, the inherit ance evidently dominant but with one probable skip. In this fam ily the hair is generally black with a few exceptions of brown hair. In pigmented hair the pigment, generally but not always in the form of granules, may be present in the medulla or bore of the hair shaft, and the cortex or wall may also contain pigment. In graying, the pigment, whether black, brown, yellow, or red, is lost from the hair, and minute air bubbles may develop in the hair shaft. In this n nr SSL DtO Fig. 46. Patch of gray hair on lower left mastoid region.
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