1910.] Some Aspects cf the Science of Breeding. 707 



We have these four possible factors influencing this 

 point : — 



1. Shape of rib bone. 2. Attachment of rib to spinal 

 column. 3. Muscular development. 4. "Marbling" 

 or infiltration of fat into the muscle tissue. 



A concrete example of a butcher's point about which it is 

 desirable to learn more may be given. Professor Wood's 

 work at Cambridge on the inheritance of face-colour in sheep 

 has led to a demand from an association of sheep breeders in 

 Australia. These Colonial flock-masters want a sheep bred 

 which combines the fleece of the Merino (which breed is a poor 

 butcher's sheep) with the good mutton carcass of the Shrop- 

 shire-down. A most important "point" in the butcher's 

 sheep is the leg of mutton. In order to get exact data whereby 

 this point may be followed from generation to generation, Dr. 

 Marshall, of the Cambridge Department of Agriculture, and 

 the writer of this article, find that the following questions have 

 to be answered : — Does the leg of mutton carried by the 

 Merino carcass fail (i.) because of the position of the sacrum 

 with regard to the haunch bones, or (ii.) because the haunch 

 bones are too flat, or, in technical words, because the pelvic 

 line from ilium to ischium is not sufficiently concave to allow 

 of proper muscular development, or (iii.) is the length of 

 haunch bone from ilium (hip) to ischium (pin-bone) deficient, 

 or (iv.) is the muscle, or flesh, covering the pelvic arch and the 

 bones of the leg deficient, or (v.) is it because of the absence of 

 fat from this particular part of the muscular system, or, in 

 other words, want of marbling? — It would seem, as judged 

 by inspection, that fat, in the case of the leg of mutton, plays 

 the more important part as a covering, and that the marbling 

 is a secondary consideration. It will easily be seen how diffi- 

 cult it is to ascertain exact data on all these questions. The 

 ewes and rams mated together had to be measured in respect 

 to all the above questions, and the positions of the sheep had 

 to be exactly the same, for experience showed that a slight 

 movement altered the alignment. A scale had to be arranged, 

 as far as possible, to determine the state of fatness of each 

 animal ; for obviously it is necessary to know if the measuring 

 standard is covering bone and muscle only, or bone, muscle, 

 and a quantity of fat. Having got the measurements in 1909 



3 D 2 



