[102] In the next paragraph Mr. Wallace says that the appendages in question "are apparently of the same nature as the 'sports' that arise in our domesticated productions, but which, as Mr. Darwin says, without the aid of selection would soon disappear." But I cannot find that Mr. Darwin has made any such statement: what he does say is, that whether or not a useless peculiarity will soon disappear without the aid of selection depends upon the nature of the causes which produce it. If these causes are of a merely transitory nature, the peculiarity will also be transitory; but if the causes be constant, so will be the result. Again, the point to be noticed about this "sport" is, that, unlike what is usually understood by a "sport," it affects a whole race or breed, is transmitted by sexual propagation, and has already attained so definite a size and structure, that it can only be reasonably accounted for by supposing the continued operation of _some constant_ cause. This cause can scarcely be correlation of growth, since closely similar appendages are often seen in so different an animal as a goat. Here, also, they run in breeds or strains, are strongly inherited, and more "constant," as well as more "symmetrical" than they are in pigs. This, at all events, is the account I have received of them from goat-breeders in Switzerland. If, however, even this should be denied, what will be said of the second case, that of the niata cattle?