20 



INHERITANCE OF COAT-PIGMENTS AND COAT-PATTERNS 



DUTCH-MARKED SERIES (SERIES D). 



The data for inheritance of spots in the Dutch-marked series are con- 

 tained in tables 5 to 14. The individuals are arranged in a series of groups, 

 each group having a larger average amount of Dutch-marked ancestry than 

 the foregoing one. For convenience in description, we may use the symbol 

 D to designate any Dutch-marked animal, followed by a numeral to indicate 

 the amount in generations of its Dutch-marked ancestry. On this basis an 

 original Dutch-marked animal, one without Dutch-marked ancestors, would 

 be designated D ; a Dutch-marked animal with one generation of Dutch- 

 marked ancestry, DI ; one with two generations of Dutch-marked ancestry, 

 D 2 \ and one with three generations of Dutch-marked ancestry, Z? 3 . Simi- 

 larly a Dutch-marked animal, one parent of which was Dutch -marked, but 

 the other not, might be designated Dj;the Dutch-marked young of 

 individuals might be called DI\ ; etc. 



The young of our Dutch-marked animals have been divided into four 

 groups, the average amounts of Dutch-marked ancestry in these groups 

 being respectively ^, i, 2, and 3 generations. Groups of individuals were 

 at first created which came midway between the groups mentioned, but 

 these differed so little from the adjacent groups that we decided finally to 

 abolish them, dividing them equally between the groups to which they 

 were intermediate. Thus a group, DI\, was divided equally between the 

 groups DI and D 2 , and a group, D 2 \> between the groups D 2 and D$. 



For each individual observed, a record was made of what spots it possessed 

 and what spots its parents possessed. These records are shown in tables 

 5, 7, 9, and 1 1 for the four groups of individuals having the mean ancestral 

 values D^, DI, D 2 , and D 3 respectively. Each table contains separate records 

 for head, shoulder, side, and rump spots. The significance of the various 

 entries will be sufficiently clear after an examination of a single category 

 (head spots) in table 5. There are for the individuals examined three pos- 

 sible conditions as regards head spots. An individual may have two such 

 spots (one on either side of the head) ; it may have only one head spot 

 (right or left, as the case may be) ; or it may have no head spots. Records 

 are made for these three conditions separately in the horizontal columns 

 marked 2 spots, i spot, and o spots respectively. For the possible head- 

 spot conditions of the two parents considered jointly, five categories are 

 necessary, 4, 3, 2, i, and o. These are indicated in vertical columns in the 

 tables. An entry in the upper left-hand square of the table signifies an 

 individual having a pair of head spots, born of parents both of which were 

 similarly marked ; an entry in the next square to the right means an indi- 

 vidual having likewise a pair of head spots, but born of parents only one of 

 which had a pair of head spots, the other having one head spot only. The 





