THE SCIENCE OF STOCK-BREEDING. 
729 
When fixity of type or prepotency to reproduce the cultivated 
characteristics is broken down bv crossing or mixing of types with 
highly fixed dissimilar improved characteristics, the unimproved 
characteristics of the original native breed speedily reassert them- 
selves, and breeds so treated soon revert to that most prepotent of all 
types for which Nature has been culling for numberless generations. 
Crossing improved breeds is the great cause of atavism or throwing 
back to the unimproved original type. 
In some cases the progeny of a cross in highly improved breeds 
is more valuable than either of the improved types of parent for cer- 
tain economic purposes, such as butchers’ meat ; but for stud purposes 
or propagating an improved type they are worthless, the power ot like 
producing like of either type being destroyed, and it would take a 
long process of grading-up to a fixed ideal to re-establish this power. 
Crossing highly improved breeds produces changes the effects of 
which no one can foretell. 
In propagating animals for the purpose of improving tlieir 
species in any particular line, very close culling is necessary in order 
to prevent constitutional weakness being established. Through the 
extra care in feeding and treatment generally of animals bred with 
valuable specialties, constitutional weakness cannot be so readily 
detected as when animals are left more to the trying vicissitudes of 
Nature, and stud animals being of high market value are often, in 
place of being culled and not allowed to breed, sold for the ostensible 
purpose of improving their species, but really to propagate consti- 
tutional weakness and consequent diseases. In animals bred for 
a specialty there is danger of abnormal developments in that special 
direction, to the neglect and injury of vital organs. The fitly building 
up or proportioning of the animal system as a whole must not be 
neglected if we would maintain constitutional vigour. 
W e sometimes hear it asked, What breeds are best ? It is impos- 
sible to give a direct answer to this, so much depending on conditions 
of climate, soil, markets, &o. Each and all our recognised improved 
breeds have particular characteristics suitable for certain environ- 
ments and economic purposes. On taking into consideration the many 
different breeds and varieties of domestic animals in the old world, 
where they have been acclimatised for numberless generations, we find 
each specially adapted to tbedistrict in which it has developed — the small 
wiry blackfaced sheep to the Scotch and Welsh mountains, the slow 
heavy Lincoln to the fens, the Highland pony to the hills, the heavy 
Clydesdale to the straths, and so on. If anyone in breeding makes 
up his mind to cultivate a type of animal that is not suited to the 
surroundings, he must be at great expense time after time in getting 
fresh improved blood to keep them near the standard he wishes, because 
he is not working in harmony with Nature’s laws. In older densely 
peopled countries direct natural influences of soil and climate can be 
and are materially modified by hand-feeding, housing, and the conse- 
quent close attention by man ; so that there is more necessity for 
taking local influences on breeds into consideration in cur vast 
territories, where the means of modifying natural conditions are as 
yet limited, and where, as Mr. Wragge, our meteorologist, says, 
“ Nearly every variety of climate except arctic is experienced.” By 
studying closely the original homes of the various old-world breeds 
