30 PRINCIPLES OF SWINE BREEDING 
Longfellows are scarce. We might think we had a second 
Longfellow, but an attempt to concentrate his blood by in- 
breeding might prove the utter ruin of the herd, because the 
boar might possess weaknesses which did not become apparent 
until his progeny were inbred. 
Cross-breeding means the mating of animals belonging to 
different breeds, and implies that both male and female are 
pure-bred. Though a good deal of cross-breeding is practised, 
very little systematic work has been done in the way of 
studying the relative merits of pure-bred and cross-bred hogs, 
and little in the best way of crossing to obtain a given result. 
Some work in cross-breeding at the Ontario Agricultural 
College gave indefinite results, so far as cheapness or rapidity 
of gain was concerned. There was nothing to indicate that 
one method of crossing necessarily gave better results than 
another, or that cross-bred pigs were necessarily better than 
pure-breds, 
J. H. Grisdale, Central Experimental Farm, Canada, 
reports cheaper gains from cross-breds than from pure-breds, 
but he failed to find that any one method of crossing was 
superior to another, so far as his work went. 
The writer’s experience leads him to believe that the progeny 
of animals which have become too fine and lack growth and 
thrift can be much improved as profitable feeders by the 
introduction of the blood of a more growthy and _ heavier- 
boned type; or that animals that are coarse-boned, or slow 
feeders, can be improved by using the blood of a finer type. 
Frequently, however, this result can be attained without resort- 
ing to cross-breeding, by selecting types within the same breed. 
In the case of thrifty, rugged pure-breds, which are of a 
type which meets the requirements of the feeder, it is difficult 
to see how any advantage is to be derived from cross-breeding. 
