. Domesticated animals and plants; a brief treatise upon the origin and development of domesticated races, with special reference to the methods of improvement. Breeding; Domestic animals; Plants, Cultivated. DoMKsru'A ri:i) animals \\n Doubling of parts. One of the most common ot" abnormalities is the increase ot numbers of ixirts, especialK' bv cUniblin,>;'. An extra linger or t(K" is by no means rare, and double thumbs or even double hands are not unknown (see V\g;. 20). The horse, having de\eloped from a fi\e-toed ancestor, has frequently an extra toe or two, as doe
. Domesticated animals and plants; a brief treatise upon the origin and development of domesticated races, with special reference to the methods of improvement. Breeding; Domestic animals; Plants, Cultivated. DoMKsru'A ri:i) animals \\n Doubling of parts. One of the most common ot" abnormalities is the increase ot numbers of ixirts, especialK' bv cUniblin,>;'. An extra linger or t(K" is by no means rare, and double thumbs or even double hands are not unknown (see V\g;. 20). The horse, having de\eloped from a fi\e-toed ancestor, has frequently an extra toe or two, as does the cow. though less commonly. Certain strains of sheep have four horns instead. KiG. 20. Symmetry within the variable part. Here it would seem that an attempt has been made to repeat the hand, or rather that an attempt at repetition of the thumb has resulted in a doubling of the hand. — After Rateson of twti. and occasionall)' the deer shows a cluster of horns instead of the nt)rmal growth. Insects frequently double a leg or a wing, and turtles and snakes occasionally double the head ; ^ indeed, there is almost no organ or part of the body that n^iv not in rare instances be doubled- (see Fig. 21). Doubling among plants is exceedinglv common, being noth- ing more or less than branching. Double clover heads are found eveiTwhere, double timothy heads rarelv, and double wheat still more rarelv. Double ears of corn, or, mt>re projx'rlv. "fingered" ears, are frequenth' found, as are little ears on the end of the tassel (see l'"ig. 19). ^ " Principles of Hreeding," pp. 44, 64, 67. - The so-called double-headed people of the shows have been in every case really twins united by fleshy growth, an abnormality that occasionally Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Da
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