IMPROVEMENT OF AGRICULTURAL HORSES. 
631 
—an animal distinguished by his compact form, fineness of 
coat, rapid growth, and great power of assimilation, or, in 
plainer terms, an aptitude to lay on fat and flesh. The tran¬ 
sition from one state to the other is not the work of a single 
generation; such changes are gradual, but they are at the 
same time sure. No common judgment is called into play 
in the application of the principle of selection ; nor is perse¬ 
verance less required. Experiments that seem to have been 
conducted in a manner to ensure success will fail, intentions 
are frustrated on the verge of fruition, and what were received 
as laws are found subject to exceptions. Trifling and un¬ 
suspected causes interfere to render well-arranged plans 
abortive, and often more than one life must be devoted to the 
perfection of a single result. It is not our province to in¬ 
quire to what extent the principle of natural selection has 
produced species and varieties, but that in nature changes of 
animal form and character have followed alterations of the 
conditions of existence is beyond all dispute. We decline to 
reason upon those changes outside the limits which experi¬ 
mental science assigns to us, nor do we desire to incur the 
responsibility of assuming positions which, however appa¬ 
rently legitimate, are of too momentous a nature to be 
accepted while one link in the evidence is wanting. Within 
these limits we are justified in asserting the possibility of 
modifying the habits and conformation of animals, by so gra¬ 
dually arranging the external circumstances that the condi¬ 
tions of their existence shall tend to the development of the 
qualities and characters we desire. 
To make this proposition plain we may offer an extreme 
illustration. Suppose some races of herbivorous animals to 
be situated in a locality where plants, their natural food, 
should gradually decrease, until they ultimately ceased to be 
available for the animal’s sustenance —assuming at the same 
time that the plant-eating animals continued to increase while 
their food was diminishing—it is possible to imagine that, 
during the scarcity of food, hunger, gradually becoming more 
urgent, would prompt them to consume the flesh of smaller 
animals that died or were accidentally killed. We may easily 
conceive that, as hunger advanced to starvation, the w'eaker 
subjects would be destroyed and consumed by the stronger. 
The young, following the example of their parents, would 
grow with an acquired taste for unnatural food, and with 
predatory habits becoming more marked every succeeding 
generation, until at length they would become perfectly 
adapted to those new conditions of existence under which 
they had been forced to live, or otherwise to die of starvation, 
