Wright: Color Inheritance in Mammals 



527 



wished but the same considerations 

 which apply in the case of roan short- 

 horns apply here. Yellow by yellow 

 seems to produce distinctly fewer yel- 

 lows than does red by light dun. No 

 doubt subsidiary factors must be as- 

 sumed to produce overlapping of class 

 ranges. Following are some figures 

 given by Wilson. The yellow by ^^ellow 

 data are from herdbooks 13, 14, 15; the 

 red by light dun from books 3 and 15. 



Red 



Yellow by j-ellow 15 



Red by light dun 4 



The factor D by which dun and yel- 

 low differ from black and red respec- 

 tively fits best into class lb and may be 

 compared with the dun factor of horses. 

 Dun cattle it is true appear to differ 

 from blacks not only by dilution of color 

 but by increase in ^^ellow, but even 

 l^lacks often show a red rustiness at the 

 tip of the hair w^hich suggests that they 

 have been selected from a type with a 

 pattern comparable to the agouti of 

 rodents. In the general dilution of 

 color brought about by factor D, the 

 reduction in density of black permits 

 the agouti pattern to become more 

 \-isible. There is probably no color in 

 cattle which can be compared with the 

 recessive blacks among rodents. The 



blacks in cattle find their best homologue 

 in the gray mice blackened by the black 

 and tan factor, or in the black rabbits 

 due to the addition of Punnett's density 

 factor to grays. 



Whether the colors which appear 

 similar in the different breeds of cattle 

 are really so genetically could only be 

 determined by careful experiments. 

 Judging by appearances it is probable 

 that the dun dilution factor of Highland 



cattle is found also in the Guernseys and 

 Jerseys. The former appear to be 

 eeDD and most of the latter EEDD. 

 Kuhlman" reports on the cross of Jersey 

 wdth black Angus. Fi was black or 

 very dark dun. In Fj black, dark dun 

 and orange fawn appeared. The general 

 level of intensity appears to be higher 

 here than in Highland cattle. 



Probably there are variations in 

 intensity which do not belong to the 

 series discussed. Wentworth^^ has re- 

 ported on a very interesting factor in 

 the dark mahogany colored Ayrshires. 

 He finds clear evidence of sex-limited 

 inheritance. Heterozygous males are 

 dark colored while heterozygous females 

 are like ordinary reds. 



War Causes Increase in Illegitimacy in Europe 



Almost every country in Europe 

 shows a slight increase in the relative 

 number of illegitimate births since the 

 outbreak of the war, according to Lmira 

 O. Lundberg of the Children's Bureau, in 

 an address before the National Confer- 

 ence of Social Work. In England and 

 Wales, for instance, between 1913 and 

 1916 the total nimiber of births de- 

 creased 10.8% while the number of 

 illegitiirate births decreased only 0.2%. 

 In Berlin, however, the number of 

 illegitim.ate births in the first fourteen 

 war months was 29%, less than in a 

 similar period before the war. France 



and Italy show some increase. At the 

 same time, all the warring nations are 

 making better provision for the protec- 

 tion and welfare of the illegitimate child, 

 thus reducing the high death rate in 

 this class of infants. As illegitimate 

 children probably represent, on the 

 average, an inferior sexual selection on 

 the part of their parents, the effect of 

 the -SAar in increasing the gross and net 

 illegitimate birth rate is distinctly dys- 

 genic. Miss Lundberg believes that 

 the war is not likely to produce an 

 increase of illegitimacy in the United 

 States. 



13 Kulhman, A. H. 1915. Jour. Her., 6:62,-12. 

 '♦Wentworth, E. N. 1916. Jour. Ag. Res., 6:141-147. 



