ANIMAL BREEDING. II5 



breeding of all animals may be based ; for it is possible, by the 

 expenditure of comparatively small sums on rabbits and poultry, 

 to unravel to some extent , the complicated skein of animal 

 heredity, and to do a good deal of the difficult " classification " 

 work which is an essential preliminary to scientific stock breeding. 

 This class of work, however, is necessarily of a character which 

 it would be difficult to explain clearly to readers who were not 

 well acquainted with the science of genetics. In fact, the 

 account of two years' investigation in animal breeding — which 

 is the broad purpose of this report in connection with other 

 branches of science — could hardly be made intelhgible to the 

 lay reader. We shall therefore content ourselves with a 

 brief summary of the more recent work at Cambridge, laying 

 stress on those aspects of the work which are capable of being 

 applied to an economic use. 



It will be desirable to explain the kind of difficulty which 

 the Cambridge Institute is attempting to solve, and this will be 

 made clearer if we refer first to a simple case of inheritance in 

 cattle, which is already well established. The breeder knows, 

 perhaps only too well, that red calves are apt to occur occasionally 

 even in the most highly pedigreed breeds of Aberdeen-Angus or 

 Holstein. They are rarely welcomed, and in most cases the 

 breeder would go to a great deal of trouble to ensure that they 

 never appeared in his herd. He tries to get rid of the taint by 

 vealing the red calves, but still they come from time to time. 

 Now it is a perfectly simple thing to remedy this position if the 

 breeder is able to appreciate the heredity principle involved. 

 The colour of the coat in this case is the outward sign of a definite 

 inheritable character contained in the germ cell. A pure-bred 

 black animal produces germ cells which contain what is known 

 as the factor for black ; a pure-bred red animal produces germ 

 cells containing the factor for red. The birth of a new animal 

 arises from the union of two germ cells. In an absolutely pure 

 black herd, every germ cell produced contains the factor for 

 black, so only black animals are possible. On the other hand, 

 if at some period in the history of the herd, a pure black animal 

 has mated with a pure red, the result will be a union of black 

 and red germ cells. In the resulting egg which is to give rise 

 to the new animal, the black factor is dominard to, or conceals, 

 the red, which is recessive ; the calf, although black in appearance, 

 will contain the red factor in 50 per cent, of its germ cells. It is 

 known as an " impure dominant " and if that animal is used 

 for breeding, a red calf is bound to appear sooner or later, either 

 in its immediate progeny or their posterity. If the breeder 

 wishes to prevent the appearance of reds in his herd he must 



