1004 EXPERIMENT STATION RECORD. 



Once these facts have been ascertained, the breeder is no longer 

 Avorking in a haphazard wny. AVhen Hurst can predict the difference 

 between the resuU of mating two pairs of rabbits, externally iden- 

 tical, because he knows the difference between their gametic constitu- 

 tion, or Ca.stle can prophesy a new variety of guinea pigs, as reported 

 on another page of this issue, the breeder has it in his hands to ac- 

 com])lish his object more intelligently and with greater certainty. 



Davenport, Hurst, Bateson, and others have found that poultry ex- 

 hibits numerous unit characteristics which are inherited in alternative 

 fashion, many of which when correlated easily separate as a result of 

 hybridization. Davenport has recently found that the crest of ca- 

 naries behaves in Mendelian fashion, as in the case of poultry and 

 pigeons. Spillman has indicated how a knowledge of Mendelian 

 characters ma^' assist in fixing the white band and in eliminating the 

 white feet of Hampshire swine without using black breeding animals. 

 From a study of stud books Harper found that in Percheron horses 

 the gray color is dominant over black, and the dam dominant over the 

 sire in the ratio of five to four; and Hurst that the ba}' and brown 

 colors of thoroughbred horses are Mendelian dominant over chestnut. 



Most of the work done in the determination of Mendelian prin- 

 ciples has been applied to morphological characters, but the practical 

 man has more concern with, physiological qualifications. If morpho- 

 logical characters behave in Mendelian fashion, there is reason to sup- 

 pose that the pln^siological characters do likewise, although this has 

 been determined in but few cases. For instance, normal mice are 

 dominant over waltzing mice; and Hurst has found that, at least in 

 some cases, broodiness in hens is dominant over nonbroodiness. 



It has been the common opinion among farmers and stockmen that 

 an acquired modification is inherited, but the study of cell division 

 under the microscope indicates that functional variations are rarely if 

 ever inherited, and that injuries and mutilations are not j^assed on. 

 The lecture before the American Association for the Advancement of 

 Science, at Baltimore, by Professor Wilson, reported on page 1071, 

 is an illustration of how microscopic studies of germ cells may throw 

 light upon the vexed problem of the determination of sex. 



Eesults of aj^plying the statistical methods, as elaborated by Que- 

 telet, Galton, Pearson, and their followers, to the problems of heredity 

 are too well known to be described here, but as yet their value seems 

 to have been less apprecinted by station Avorkers in animal breeding 

 than in plant breeding. The breeding of the larger domestic animals 

 is slow and costly, but fundamental principles remain the same 

 throughout the animal kingdom, and much can be done, at least in a 

 preliminary way, by working with small animals which reach ma- 

 turity in a few weeks or months. Though the primary interest may 



