THE SEGREGATION OF RACIAL EYE-COLOUR.
By Geo. P. Mudge.
It is a matter of importance to know the exact influence which a mixture of races exerts upon the hereditary transmission of characters. For instance, do the alternative characters of two races of men, when they are related by marriage, segregate in inheritance in accordance with Mendelian principles? Is the term "blending or fusion of races misleading, and only accurate when employed in a qualified sense"?
It has been shown by Mr. Hurst's very careful investigations in a Leicestershire village that certain types of human eye-colour, which he designates as "Simplex" and "Duplex," are inherited in complete accord with Mendelian principles of inheritance. The two types not only segregate from each other in the course of transmission, but they do so in practically exact Mendelian proportions. And the "Simplex" type, which is the recessive form of eye-colour, breeds true. It begets nothing but the Simplex eye. These results have been confirmed by Professor and Mrs. Davenport in America. In this and similar cases we are merely dealing with the transmission of alternative characters in individuals of the same race. [D]
[ [D] Of course, the "English" race is really a community of many commingled races. But from our present standpoint that matters little. It is rather confirmatory of the further facts and conclusions I am about to describe.
But one of the interesting problems of the future is concerned with the transmission of characters when human races of diverse characteristics breed together. We are not concerned to discuss now whether the races of mankind are varieties or species.
SPANIARD v. GIPSY.
The records of travellers provide certain information which helps us to form reliable though limited conclusions as to the results of the interbreeding of different human races. Mrs. Rose Haig Thomas, to whom we are indebted for the exhibit of a photograph, taken during a journey through Spain a few years ago, of a Spanish gipsy woman with her three children, has made several observations of some interest. She became acquainted with a family in which "the mother was a dark-skinned, black-haired, black-eyed gipsy woman. (See photograph, Exhibit No. K 3.) The husband was a Spaniard with blue eyes. There were three children. Of these, the eldest had flaxen hair and blue eyes. The second was a boy with black eyes, black hair, and an olive skin as dark as the mother's. The third child was too young to justify any conclusion being based on its characteristics. It was only 18 months old; but was flaxen-haired, blue-eyed, and fair skinned." This observation of Mrs. Haig Thomas, in Granada, affords then a clear example of the segregation of blue-eye and flaxen-hair characters among the gametes of the black-eyed, black-haired, and olive-complexioned mother. For, in the light of Mendelian researches, it is obvious she was carrying these characters recessive, and that some of her gametes were pure in respect of them.
ARAB v. SPANIARD.