PREPOTENCY. It is generally assumed that an old species or variety is prepotent over a more recent species or variety. tt is impossible to say whether zebra hybrids in their markings take after a remote zebra ancestor, or after an ances t-or common to both zebras and horses, or after a hypothetical mid-parent combining the characters of the less remote ancestors of both zebras and horses. There is, however, no difficulty in seeing that while sonic zebra hybrids, apart from their stripes, closely resemble the zebra parent, others take after their horse parent, thus showing that the wild sire is not necessarily the most prepo lent. "But even when the hybrids are distinctly horse-like they never repeat recently acquired pe culiarities, such as a blaze, or short ears, high withers, or a small head and long neck." He believes that sports and certain marked variations are often prepotent ; and also that in breeding (see Caoss•FEnTiLizATiox) is "common among wild animals, and that by indueing prepo tency it plays an important part in the origin of species." It may be here observed that Ewart's
experiments lead him to reject telegony (q.v.), and to explain such occurrences by cases of rever sion. The zebra hybrids are also interesting as being "in some respects almost intermediate between their parents." Each parent, he says, hands on its most fixed individual characters. His zebra hybrids are neither new creations nor yet intermediateaforms.
Sterility in Hybrids.—Ewart concludes that, as there is no hard and fast line between species and varieties, there can be "no fundamental difference between a hybrid and a cross, nor yet any a priori reason why any given hybrid should be sterile, or any given cross fertile." "Sterility has doubtless been acquired in some cases slowly, in others ab ruptly, but how it has been acquired it is im possible in most cases even to guess."