Breeds and Breeding

The principles governing the production of breeds of plants or animals are included under the three heads of HEREDITY, VARIATION, and SELECTION (q.v.). The breeder must have a clear idea of the form and purposes of the breed he is seeking to establish, and a keen eye to discern spon taneous individual variations. He can hasten the establishment of a breed by inbreeding, i.e., pairing sire and daughter, etc., but must not push this too far, because most of the breeds thus established lack constitution. He can in a measure increase the effects of a cro by separating the close relatives that are to be paired and subjecting them to diverse environments for a considerable period before they are paired. In this way, if two breeders work for the same ends in different countries or localities, they do well to interchange their breeding animals. It is also considered that a variety is more readily established through using the male first and persisting until the same points are fixed in the daughter. This means that (1) males are more variable; (2) males are prepotent in transmitting their qualities to their daughters; (3) certain female characters really transmitted by the male, but latent in him, appear in the daughters, and are to be considered as really belonging to the strain which the male represents; e.g., the tendency to give better milk may be transmitted through a bull. All that is needed the edge that if the daughters of such a sire resemble him, have inherited his nature, they also are better cows. In other words, neither male nor female represents the entire characteristics of the race; both sexes are present in each animal, but one sex is latent. Again, it must be remembered that all the race characters do not appear in any pair, but that some are usually latent, and, further, that the ones that are developed are brought out during development by certain external conditions. this way a new character may depend for its existence on some local or temporary cause perhaps perhaps connected with a peculiar environment; in which case a change of locality may destroy troy the variety, and the older characters alone will be developed. developed. This is atavism or reversion. Such loose characters may, by long breeding, become so fixed that they will not revert; the old race characters were once just as superficially rooted. The last new acquirement is always the least stable and must be carefully nursed or cultivated until it has become well rooted. Brehm, ALFRED EDMOND, 1829-1884. Director of the Zoōlogical Garden at Hamburg 1863-67; founder of the Aquarium at Berlin 1867. Thierleben , 10 vols., 1863-68.