716 



THE AMERICAN NATURALIST 



[Vol. XLV 



All of these theoretical types seem to occur except the 

 roan of type 3, which phenomenon will be discussed 

 further on in this paper. 



With these nine theoretical types of individuals the 

 following forty-five type matings are possible. (The 

 numbers following the color designations refer to the 

 above table describing the individuals somatically and 

 gametically. ) 



These forty-five cases typify the behavior of two com- 

 panion traits of opposing patency in their dominant 

 phases, thus explaining the behavior of one type of 

 apparent or somatic blend, which is in fact the resultant 

 somatic effect of the lack of synchronism in the behavior 

 of genetically independent units. 



With these matings it is noted that the cases joined by 

 an arrow (cases 8 and 9, 10 and 11, 13 and 14, 17 and 18, 19 

 and 20, 22 and 23, 32 and 33, 34 and 35, and 37 and 38) are 

 reciprocal cases wherein the same parental elements 

 enter and the same offspring are expected, but these 

 parental elements are differently combined in each pair 

 of parents — different somatic but identical gametic 

 matings. These principles fit the previously observed 

 facts as follows: As to the attempt to establish a race of 

 Red Shorthorns, the above mating No. 30 (a red by red) 

 expects 25 per cent, roan offspring and amply accounts 

 for the occurrence of roans in such a cross. This phe- 

 nomenon is equally well accounted for by the simple 

 hypothesis that red is dominant ; some reds are simplex. 

 It is known that breeders in attempting to eliminate 

 white, spotted and roan from their stock simply 

 destroyed the "off color" calf — the genotypic germ 

 plasm that produced it being continued in the herd. 

 There are, however, reds which will produce only reds, 

 as in matings Nos. 6 and 15. 



Mr. Spangler's white bull was produced by two roan 

 parents; such color is expected from such a mating in 

 one fourth of the offspring of matings Nos. 25, 26, 37 ; in 

 three sixteenths of No. 28 and in one half of No. 34. His 

 whiteness is of either type 6 or type 9 and consequently 



