On the other hand, from the cross between the darkly pigmented Eastern races and the white segregation seems to occur in subsequent generations. Families are to be found in which one parent is a pure white, while the other has arisen from the cross between the dark and light in the first or some subsequent generation. Such families may contain children indistinguishable from pure blonds as well as children of very dark and of intermediate shades. As an example, I may give the following pedigree, which was kindly communicated to me by an Anglo-Indian friend (Fig. 29). The family had resided in England for several generations, so that in this case there was no question of a further admixture of black. Most noticeable is the family produced by a very dark lady who had married a white man. Some of the children were intermediate in colour, but two were fair whites and two were dark as dark Hindus. This sharp segregation or splitting out of blacks and whites in addition to intermediates strongly suggests that the nature of the inheritance is Mendelian, though it may be complicated by the existence of several factors which may also react upon one another. Nor must it be forgotten that in so far as these different factors are concerned the whites themselves may differ in constitution without showing any trace of it in their appearance. Before the case can be regarded as settled all these different possibilities will have to be definitely tested. With the dark Eastern races as with the negro we cannot {132} hope to come to any conclusion until we have evidence collected by critical and competent observers. Though for the present we must regard the case of the negro as not proven, there are nevertheless two others in which the heredity would appear not to follow the Mendelian rule. Castle in America crossed the lop-eared rabbit with the normal form, and found that the F_1 animals were intermediate with respect to their ears. And subsequent experiment showed that, on the whole, they bred true to this intermediate condition. The other case relates to Lepidoptera. The speckled wood butterfly (_Pararge egeria_) has a southern form which differs from the northern one in the greater brightness and depth of its yellow-brown markings. The northern form is generally distinguished as var. _egeriades_. Bateson crossed the southern form from the south of France with the paler British form, and found that the offspring were more or less intermediate in colour, and that in subsequent generations the parental types did not recur. These cases at present stand alone. It is possible that further research may reveal complications which mask or interfere with an underlying process of segregation. Or it may be that segregation does not occur owing to some definite physiological reason which at present we do not understand.