34 N. lr. AGR. EXPERIMENT STATION. [Bulletin 151 



Color of pigment of skin and wool are indicated as to position on the body by 

 a diagram and as to extent by a numerical percentage grade. All of these 

 diagrams are so made that they can subsequently be reproduced in print 

 Accurate measurements are taken of the length and circumference at base 

 of horns, if present, the result being represented in a ratio of length to cir- 

 cumference. In fact, no measurement is taken of any part of the anatomy 

 without comparing it in ratio with some other. It is the only means of being 

 able to recognize, between animals, relative differences of many features. 



Hair color has involved a very great amount of detailed study; owing to 

 the fact that most of the parent native ewes were heterozygous in this respect 

 in the first instance We anticipate, however, little difficulty in distinguishing 

 its action in heredity, as it plainly follows the general rule, namely, dominance 

 of the greater pigmentation over the lesser The F x heterozygotes produced 

 from a cross between sheep, possessing respectively very dark and pure white 

 hair color, usually present a mosaic appearance. However, in every instance 

 there is a clear preponderance of the black color. It also appears from experi- 

 mental evidence we have on hand that skin pigmentation in sheep is inherited 

 in a similar fashion. This knowledge to sheep breeders should prove a decided 

 boon, as the dark skin is a feature that shepherds greatly dislike and have 

 long fought against. 



The inheritance of horns, so far as the F! generation is concerned, from which 

 we alone can judge, seems peculiar, although in harmony with T. B. Wood's 

 sheep-breeding experiments (October, 1909, issue of the Journal of Agricul- 

 tural Science) . When a horned sheep is crossed upon a hornless, — it matters 

 not which sex bears the horns, — all the male Fj offspring are horned, while 

 all the female Fj offspring are hornless or virtually so. In no case are the horns 

 of the Fj rams so strong or large as those of the homed parent, although in 

 every case they were much greater than what are commonly called scurs. 

 Only about twenty per cent, of the F! ewes developed any appearance of 

 horns and these were but slight, loose scurs. The explanation involves 

 many complications, and we shall not_ dwell upon it at any great length in 

 this report. The foregoing evidence shows that the inheritance of horns 

 in sheep is apparently in some manner connected with sex. It is, evident, 

 however, that the horned condition is dominant; its absence, or the polled con- 

 dition, recessive; but that in females something essential to the somatic devel- 

 opment of horn is missing. It is possible that the production of horn depends 

 upon a positive character or determiner + a material elaborated by the male 

 germ glands and that in the absence of such material the horn fails to develop. 



From a study of the F a offspring, distribution of wool, as applied especially 

 to the face, ears and legs, seems to be inherited in a most simple fashion. 

 When a sheep heavily wooled upon poll and/ace is crossed with one not wooled, 

 the F | displays wooling on poll andjace but in less degree than the mosl heavily 

 wooled parent. This applies in similar fashion to distribution of wool on 

 ears and legs. Therefore, from this evidence this theory may be declared; 

 namely, the more extended or greater distribution of wool dominates over the 

 less extended or sparser covering. 



