486 



The Journal of Heredity 



of a bird with respect to the particular 

 character or characters. It will also 

 often serve as a means to prevent the 

 beginner in poultry breeding from 

 making mistakes. 



Unfortunately, however, the domi- 

 nance of one of a pair of characters over 

 another is in most cases not compbte. 

 As a consequence, results are not 

 sufhciently exact and clean-cut to allow 

 the application of the principles of 

 Mendclism with assurance and reason- 

 able certainty. Because the character 

 or characters do not segregate in a pure 

 state, it iDCComes necessary for the 

 breeder to adopt a system largely 

 empirical, with the object of using in 

 his matings those individuals or lines 

 which show the greatest purity in this 

 respect. In other words, he must 

 depend very largely as a basis of selec- 

 tion of breeders upon the results 

 obtained in the offspring. He is unable 

 to predict with sufficient certainty just 

 what the results will be. Now this is 

 exactly the position which the practical 

 breeder has always occupied. He must 

 select his breeders upon the basis of 

 their apjjearance, upon his knowledge 

 of their ancestry and principally upon 

 the results obtained from breeding 

 them. Therefore, while the Mendelist 

 uses as his guide in breeding, the 

 principles of Mendel's Law and the 

 practical breeder uses the knowledge 

 accumulated through experience, the 

 methods used by each to secure a 

 desired result in actual ]:)ractice are 

 identical or nearly identical. There is 

 little in the data so far obtained as 

 the result of experimental breeding 

 which will enable the ])ractical breeder 

 to breed with a much greater degree of 

 certainty or which would enable him 

 to change his operations for simpler 

 procedure. 



BREEDIN'C. FOR HOCS 



Dr. Pearl in connection with his 

 hyjjothcsis of the method of inheritance 

 of high fecundity, advances for the 

 l)enefit of the practical ]X)ultry breeder 

 a \Aan for imjjroving the average egg 

 production of his flock. This consists 

 of the following steps : 



(a) Selection of all breeding birds on 



the basis of constitutional vigor and 

 vitality ; 



(6) The use as breeders of such 

 females only as have shown themselves, 

 by trap nest records, to be high pro- 

 ducers ; 



(c) The use as breeders of .such inales 

 only as arc known to be the sons of high 

 ])rodvicing dams; 



(d) The use of a pedigree system by 

 which it is possible to tell the sire of 

 any particular bird ; 



ie) The making of a large number of 

 matings so as to use as many different 

 male birds as possible and ; 



(/) The continued but not narrow 

 inbreeding of those lines in which there 

 is a preponderance of daughters which 

 are high producers. 



In connection with this plan it only 

 remains to point out again that such a 

 plan is identical or very nearly so with 

 the steps which any intelligent breeder 

 of experience would take if he attemjjted 

 to make any systematic effort to better 

 the egg production of his stock. The 

 only point where it might differ would 

 be in the matter of testing out the 

 \'arious males and breeding those lines 

 showing the greatest promise. How- 

 ever, any poultryman who is sufficiently 

 interested in his breeding to make an 

 attempt to keep a pedigree record of 

 his birds, or at least a pen record — 

 and many of them do — would certainly 

 fail in intelligent effort if he did not 

 concentrate his breeding on those lines 

 which showed mo.st favorable results. 



The experimental breeding of poultry 

 has undoubtedly been of benefit to the 

 jjoultry industry generally. Not only 

 has it given us a considerable amount 

 of information as to the manner in 

 which characters are inherited but by 

 arousing interest in the subject, it has 

 cau.sed ])oultrymen to give more careful 

 thought to the jjroblems by which they 

 are confronted. It has also called 

 attention to the necessity of keeping 

 more exact pedigree records and by .so 

 doing will undoubtedls- bring about 

 much more systematic efforts which 

 will in turn lead to greater jjrogress. 



The work which has already been 

 reported and the interest aroused has 

 brought about the inauguration of 



