448 GENETICS IN RELATION TO AGRICULTURE 



ronmental conditions, therefore, those breeds of livestock which have been 

 improved in older localities have been utilized in the newer agricultural 

 regions such as those of the United States with little if any impairment of 

 their superior excellence. We see this fact expressing itself in the importa- 

 tion of large numbers of animals representing the established breeds of other 

 countries; Shorthorn cattle from England, Jersey cattle from the island of 

 Jersey, Percheron horses from France, and many other notable examples. 



In the second place questions of expediency intervene, and this is 

 particularly true when the larger domesticated animals, horses and cattle, 

 are considered. It is usually a simple thing for a plant breeder to grow 

 a thousand individuals in order to try out some idea, but it is out of the 

 question for a practical animal breeder to do so. Ordinarily his system 

 of breeding is dictated by the rigid requirements of the highest total 

 result, he cannot like the plant breeder seek for the one individual 

 among thousands and then satisfied at finding it discard the rest. Too 

 few generations can be obtained in a limited time, too great expense 

 attaches to the raising of progeny which must finally be for the most 

 part rejected, and too great difficulty arises from the universal occurrence 

 of bisexuality among domesticated animals for him to attempt to follow 

 the methods of the plant breeder. 



In the third place, and this perhaps is the most important item, animal 

 breeding has progressed to a higher relative state of excellence than plant 

 breeding. With practically all domesticated animals the herdsman has 

 known individually every animal under his care, not only from the stand- 

 point of individual excellence, but with respect to ancestral worth as well. 

 Famous individuals have arisen from time to time the merits of which 

 have attracted the attention of all herdsmen interested in the breeds to 

 which the animals have belonged, and if they proved to transmit their 

 good qualities in any degree, advantage has been taken of the best pos- 

 sible matings to insure the perpetuation of those qualities. This process 

 has gone on to a notable extent in some breeds and with remarkable 

 results; in some breeds it is estimated that not more than 5 per cent., 

 or one individual in twenty, of early animals is represented in the pedi- 

 grees of animals living today. The inevitable result of such methods 

 has been to raise the level of the breed to a very high plane, to a position 

 where the only means of improvement lies in a consideration of the finer 

 points of function and conformation, and in methods of maintaining 

 more rigidly the high standards which have been erected. These then 

 in the main are the problems which confront breeders of the best types 

 of livestock; and they are problems, which we may admit frankly, 

 have been handled admirably by the more proficient livestock breeders. 



The Service of Genetics. The geneticist, whether laboratory investi- 

 gator or philosophical theorist, cannot but admire the excellence of the 



