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 to prevail? In the face of some of the preceding chapters and these considerations, in-breeding must escape the charges against it with at least the Scots verdict, not proven. When once a breed has been established, however, that is to say, when it has reached such a degree of steadiness that it can be called "pure," the need for in-breeding is greatly decreased.

But what of the future? Does the past offer any guide? Previous to the discovery of Mendel's work, the dictum of the past as to the conditions for success in cattle-breeding would have been—

(i) A good judge.

(ii) Good stock.

(iii) Line breeding with old-established and in-breeding with new breeds.

(iv) Ruthless elimination of the unfit.

But although Mendelism would not alter the dictum it would increase the breeder's power by increasing his knowledge of the working of Nature's laws. Already in this paper such of the Mendelian knowledge as is yet known with regard to cattle is referred to. So far that knowledge is not great, and it is largely concerned with comparatively unimportant matters, like colour, for instance; but as the signs by which Mendelian characters can be identified become better known, it is hoped that information about much more important matters than colour may