128 ON THE CHEVIOT BEEED OF SHEEP. 



at the same time, it sliould be stated that among Cheviot sheep 

 it has not been practised to the same extent as among some other 

 breeds, of which the flocks kept are less numerons. It is only 

 by affinity in blood that character can be fixed and retained, and 

 that a strong family resemblance can be given to a flock, and an 

 impressive size obtamed. But, on the other hand, there is this 

 danger connected with this system, that when it is carried to an 

 extreme it leads to a loss of constitutional vigour and fertility, 

 and this danger is all the more to be kept in view seeing that 

 the evils develop themselves gradually. The strongest advocates 

 of the principle of " in-and-in " breeding have, it is well known, 

 taken great care to observe secrecy as to any cross they may 

 have introduced into their flocks, in order that their reputation 

 as breeders for special quahties might not suffer ; but there can 

 be no doubt that they, like others, have been compelled to guard 

 against the weaknesses induced by too close relationsliips. As to 

 the exact number of crosses that should be allowed, it is im- 

 possible to lay down any rule. It is, however, to be remembered 

 tliat when a cross is made with altogether new blood, long lost 

 characteristics are generally brought up in the offspring, and a 

 greater amount of variability introduced. When, therefore, a 

 sheep of a chfferent family is used, a selection should be made 

 of an animal possessing those pomts that are being worked 

 for, or, it may be, of its having those qualities that may be 

 expected to remedy defects in the original strain. In using 

 this animal the breeder should restrict Imnself, in the first 

 instance, to a comparatively small number of his best ewes, from 

 the offspring of which he can then make a choice of tups to be 

 retained for further crossing, this method having been found, 

 where acted upon, very successful. Wlien these trials are being 

 made, the closest attention is necessary, as even with likely-look- 

 ing animals the results are often disappointing. In following out 

 the principle of selection, the systematic prosecution of one idea 

 through a long course of years is necessary, as it is only by con- 

 tinually striving after the attainment of a type which is present 

 to the mind of the breeder, and working mth varieties of animals 

 that will lead up to this mark, that any breed can be permanently 

 altered. One important circumstance to be remembered in the 

 management of stock is the attention demanded by the law of 

 co-relation, — a law which connects the presence of one pomt in 

 an animal with the presence of some second or attendant char- 

 acteristic, and which is as yet very imperfectly understood. Of 

 the operation of this law, Darwin has given numerous instances. 

 White cats with blue eyes are, for example, almost invariably 

 deaf ; and pigeons that are feathered on the outside of their legs 

 and on their toes have generally their two outer toes connected 

 with a membrane. Among Cheviot sheep it lias been observed 



