Not to enter into details of the matings, statistics gathered by Mr. and Mrs. Davenport show that, two flaxen-haired parents have flaxen-haired children; two golden-haired parents have only golden-haired children; two parents with light brown hair have children with hair of that color or lighter, but never darker; two parents each with dark brown or black hair may have children with all the varieties of hair-color. Summing together a series of recessives Davenport points out that two blue-eyed, flaxen or golden and straight-haired parents will have only children like themselves. [Illustration: FIG. 21 Diagram showing descent of brachydactyly through five generations; black symbols indicate affected individuals; [male], male; [female], female (after Farabee).] =Irregularities.--=If a dominant trait or defect depends on more than a single factor, as is sometimes the case, or if it is modified by sex or other conditions, as is true of certain characters, some of which, such as color-blindness, have already been examined, then we shall find some apparently non-affected individuals having affected offspring. Certain diseases, for example, are generally transmitted by affected members of the family to their children in the expected Mendelian ratio for a dominant, yet an occasional skip of a generation may appear in which an apparently perfectly normal individual transmits to his children what, except for the omission in his own case, appears to be an ordinary dominant character. This occasional lapse in the appearance of a character when theoretically it should appear is doubtless due in some instances to the fact that what is really inherited is a _tendency_, and although this is present in the apparently normal individual, for some reason the condition itself has not appeared. This might especially be true in the case of a disease which does not manifest itself until late in life. In other cases there are undoubtedly complicating accessory conditions which modify the behavior of the trait somewhat. OTHER CASES OF DOMINANCE IN MAN Among other normal characters in man, as far as available evidence goes, dark skin is dominant to light skin; normally pigmented condition to albino; and nervous temperament to phlegmatic.