that they sprang from a common parentage. 
710 REPORT OF THE COMMISSIONER OF AGRICULTURE. 
merits of the sire and dam, the grandsire and grandam, and so on 
backward, our chances being in proportion to the strength and unity 
of the inheritance. If we find trotting and trotting-bred ancestors 
for four or five generations backward, we can expect success in a 
measure corresponding to the trotting merits of these ancestors, and 
especially the immediate ones, and the nearer we find a blood line 
broken by the influx of a current calculated to neutralize the trot- 
ting instinct, the greater is the danger of our colt developing ten- 
dencies averse to the steady, fast trot. 
All the varying types of animals of the same species are descend- 
ants of common ancestors. The clumsy, lumbering cart-horse and 
the fleet and beautiful racer have come to us from a common source. 
The difference from the original type, or rather the evolution of 
many types from one, are the result to effect which many and com- 
plex causes were contributive. The same variety of animals sub- 
jected to different environments, conditions, and uses will through 
time so change in characteristics that the unthinking would question 
A radical divergence from an original type can he effected, and 
indeed, a variety created, we might say, by developing a special 
acquired characteristic by exercise and use, and by breeding for the 
perpetuation and reproduction of that special characteristic. When 
_ racing began in England horses were trained and used for the race 
and then selected to breed for their racing capacity. Thus through 
a long series of generations the English evolved from the coarse na- 
tive stock and the Arab a horse essentially different from either, 
and vastly superior to either in the special use for which the variety 
is bred—the capacity to race at the gallop. The evolution of the 
trotting breed, yet in its infancy, proceeds on the same principle. 
The offspring of the first pair in which a special habit was devel- 
oped would, as a rule, excel at that habit more readily than either 
of their pa:ents. But as reversion to more or less remote ancestors 
is a principle in inheritance, the offspring of this pair might inherit 
strongly the characteristics of their grand parents, in which the 
special habit for which the breeder is striving has not been acquired. 
Hence, early after grafting a quality in the blood the transmission of 
that quality is very uncertain. The chances of reversion to grand 
arents are much less than to parents; to great-grand parents much 
ess than to grand parents, and soon, The risk of reproducing an 
undesirable quality of an ancestor is lessened as we breed away from 
that ancestor. On the other hand, by developing an acquired habit 
in every generation and selecting and mating parents possessing 
that habit or qualification in the highest degree, we gradually fix it 
as a matter of inheritance and instinct, and in each generation, as 
we proceed, the certainty of success in reproducing the desired qual- 
ification becomes greater and the risk of failure less. If, then, every 
ancestor for all near (say five or six) generations were trotters our 
chances of producing a trotter are very great, but if some of the 
ancestors were not trotters or trotting bred a reversion to them is 
possible, The danger of failure te produce the quality we desire in- 
creases just in proportion to the number and contiguity of the an- 
cestors not possessing that quality in the inheritance. ‘‘ Heredity 
transmits with certainty only what becomes a fixed characteristic 
in the race.” | 
The influence of selection in breeding can hardly be overrated, 
and the breeder who is wise will never forget that the dam is at 
