[13] A very striking fact may be related in this connection, which while it may or may not have a practical bearing on the breeding of domestic animals, shows forcibly how mysterious are some of the laws of reproduction. It is stated by the celebrated traveler, Count de Strzelecki, in his Physical Description of New South Wales and Van Dieman's Land. "Whenever," he says, "a fruitful intercourse has taken place between an aboriginal woman and an European male, that aboriginal woman is forever after incapable of being impregnated by a male of her own nation, although she may again be fertile with a European." The Count, whose means and powers of observation are of the highest possible order, affirms that "hundreds of instances of this extraordinary fact are on record in the writer's memoranda all recurring invariably under the same circumstances, all tending to prove that the sterility of the female, which is relative only to one and not to the other male is not accidental, but follows laws as cogent though as mysterious as the rest of those connected with generation." The Count's statement is endorsed by Dr. Maunsell of Dublin, Dr. Carmichael of Edinburgh, and the late Prof. Goodsir, who say they have learned from independent sources that as regards Australia, Strzelecki's statement is unquestionable and must be regarded as the expression of a law of nature. The law does not extend to the negro race, the fertility of the negro female not being apparently impaired by previous fruitful intercourse with a European male. In reply to an inquiry made whether he had ever noticed exceptional cases, the Count says: "It has not come under my cognizance to see or hear of a native female which having a child with a European had afterwards any offspring with a male of her own race." The Count's statement is suggestive as to the disappearance of the aborigines of some countries. This has often been the subject of severe comment and is generally ascribed to the rum and diseases introduced by the white man. It would now appear that other influences have also been operative. [14] Carpenter's Physiology, new edition, page 783. CHAPTER IV. ATAVISM, OR ANCESTRAL INFLUENCE. It may not be easy to say whether this phenomenon is more connected with the law of similarity, or with that of variation. Youatt, in his work on cattle published by the Society for the Diffusion of Useful Knowledge, inclines to the former. He speaks of it as showing the universality of the application of the axiom that "like produces like"--that when this "may not seem to hold good, it is often because the lost resemblance to generations gone by is strongly revived." The phenomenon, or law, as it is sometimes called, of atavism,[15] or ancestral influence, is one of considerable practical importance, and well deserves careful attention by the breeder of farm stock.