246 



The Journal of Heredity 



used for breeding purposes if it is possible 

 to avoid them. The significance of 

 these two types of yellow is alread\' 

 known in the case of rabbits and 

 guinea-pigs and will, I believe, become 

 apparent to all who breed dogs with an 

 eye to testing the validity of Menders 

 Law of heredity. 



If we now turn to the tabulation of 

 the matings of pointers from the Ameri- 

 can Kennel Club stud books, the follow- 

 ing results arc obtained : 



sions as to the relative position of the 

 various factors involved. 



Hagcdoorn has stated that, in the 

 case of dachshunde, yellow is epistatic 

 to black, that is to say that restriction 

 of brown and black pigment is dominant 

 over the extension of these pigments. 

 This is a point of very great interest, 

 for if carefully executed exiicrimcnts 

 could be carried out we should have a 

 chance to investigate the behavior of a 

 dominant and of a recessive vcllow in 



From an examination of this table 

 it will be seen that liver appears to be 

 hypostatic to black, and yellow, in 

 turn, hypostatic to liver. We know, 

 however, that there are two visibly 

 different types of yellows and this, 

 together with the facts stated above, 

 suggests the hypothesis that wc are 

 here dealing with two pairs of Mendelian 

 factors. These factors we may designate 

 as: 



B : The factor for black pigment 

 which is absent from brown (liver) 

 animals. 



E: The factor for extension of 

 brown and black pigment in the 

 hair. In the presence of this factor, 

 animals have spots of brown or 

 black pigment on a white ground; 

 in its absence the colored spots on 

 the coat are yellow of various 

 shades. 



The table given abox'c shows that 

 black crossed with black produces occa- 

 sionally brown young. On the other 

 hand, brown crossed inter se give no 

 black ofTsjjring in a total of over 300 

 young. This last mentioned type of 

 mating does, however, produce some 

 yellow young as well as brown ones. 

 These facts seem to justify the conclu- 



forms that were perfectly fertile when 

 crossed. This would afford an oppor- 

 tunity to obtain data of great importance 

 on a point of considerable theoretical 

 interest in genetics. 



To return to the case of pointers, we 

 should then expect to find the four 

 following visiblv different zvgotic tvpes. 



1. BE— Black; 



2. bE — Brown (liver); 



3. Be — Yellow (black nose) ; 



4. be — Yellow (brown nose). 



We may now consider in detail'cer- 

 tain matings which indicate the^exis- 

 tence of these four types. 



SOME INTERESTING MATINGS. 



Type 1— Black. That black is of this 

 constitution is shown first by the black 

 X black matings (see table) which pro- 

 duce liver young; and second, by the 

 fact that black by liver may produce 

 yellow young. The appearance of 

 these two hypostatic forms in crosses 

 in which at least one j^arent is black, 

 and the fact that no black animals are 

 formed as the result of mating liver x 

 Hver or yellow x yellow, show that 

 blacks possess factors which both >'el- 

 lows and livers lack. 



Type 2 — Brown. That these animals 

 lack the factor B is shown bv the fact 



