602 
LECTURES ON HORSES. 
extent and in that direction which is needed for the action of the 
parts ; and the muscles or acting powers superadded to it, are so 
applied and distributed upon it, that, while they are enabled to 
move every part in the manner it was designed to move, they, so 
far from encumbering or disfiguring the frame-work, confer upon 
it beauty of form and handsome exterior. It is true that the mus- 
cles might have been placed greatly more to their advantage as 
moving powers ; but in such case not only must outward appear- 
ances have been sacrificed, but the form of the animal would have 
turned out such as would have materially interfered with his present 
functions and uses : thus what he had gained in power he would 
have more than lost in inaptitude and encumbrance. 
The bones, in their figure and in the construction of their joints, 
offer every facility compatible with the general form of the animal, 
to the agency of the muscles, the power of the latter depending 
upon that facility, which is greater in some subjects than in others, 
and upon their own magnitude and texture. The principle upon 
which movement is effected is that of the mechanical power of the 
lever — the greater the leverage presented by the bones, the greater 
the effect of the action of the muscle upon it ; and as muscles, gene- 
rally speaking, possess power commensurate with their size, the 
larger the muscle the greater its power of contraction or action. 
These are the two leading principles on which depend the powers or 
strength of an animal ; there is a third, also to be taken into con- 
sideration, which is the texture of the muscle, the quality of its 
fibre or component parts. That horse whose bones are so formed 
and arranged as to offer the longest or most advantageous levers, 
will, cceteris paribus , prove the strongest or most powerful : sup- 
posing, however, his muscles to be deficient in power, from want- 
ing bulk, or from being lax or adulterated in composition, his 
length of lever will prove of little profit to him. The same may 
be said in cases where the muscles are powerful, but the leverage 
short or upright, and consequently disadvantageous. 
In the course of our investigation into the quality of bone in 
horses of different breeds or kinds, we detected a manifold differ- 
ence between the solidity and texture of the bone of the cart-horse 
and that of the race-horse ; and if we prosecute our inquiries still 
further, we shall find some such difference existing between the 
muscular fibre of the high and that of the low bred animal. In 
proportion as the fibres of flesh run fine and free from adulteration 
of adipose and cellular tissue, so are they apt and powerful in 
action. The heart is one of the finest and cleanest muscles in the 
body, being required to act with promptness, energy, and duration ; 
and for the same reasons blood-horses are constituted of finer and 
cleaner muscular fibre than cart and mongrel-bred horses. 
