490 
LECTURES ON HORSES. 
(called by us the arm) at an angle with the humerus. Were these 
bones connected together in a straight line, end to end, the shock 
of alighting would be conveyed through a solid column, and the 
bones of the foot or the joints would suffer from the concussion. 
When the rider is thrown forwards on his hands, and more cer- 
tainly when he is pitched on his shoulder, the collar-bone is broken, 
because, in man, the bone forms a link of connexion between the 
shoulder and the trunk, so as to receive the whole shock ; and the 
same would happen in the horse, the stag, and all quadrupeds of 
great strengtli and swiftness, were not the scapula sustained by 
muscles, and not by bone, and did not the bones recoil and 
fold up.” — “ Much of the strength, if not the freedom and rapidity 
of motion, of a limb, will depend on the angle at which the bones 
lie to each other ; for this mainly affects the insertion, and, con- 
sequently, the power of the muscles. We know, and every 
moment feel, that when the arm is extended we possess little 
power in bending it ; but as we bend it the power is increased, 
which is owing to the change in the direction of the force acting 
upon the bone, or, in other words, because the tendon becomes 
more perpendicular to the lever.” 
We have already shewn that the scapula possesses a rotatory 
sort of motion upon the ribs, and that the sphere of its motion be- 
comes increased by its degree of obliquity. Sir C. Bell has ex- 
plained the cause of this — “ the serratus muscle” — the fleshy at- 
tachment of the scapula to the trunk, and the means through 
which the latter is suspended — “ when the scapula is oblique, has 
more power in rolling it.” Other muscuiar advantages likewise 
accrue. “ When the scapula lies at right angles with the humerus, 
the muscles which are attached to the latter act with more effect. 
And on the same principle, by the oblique position of the humerus, 
and, consequently, its obliquity in reference to the radius and ulna, 
the power of the muscle inserted into the olecranon is increased. 
On the whole, both power and elasticity are gained by this posi- 
tion of the superior bones of the fore leg. It gives to the animal 
that springs a larger stretch in throwing himself forward, and se- 
curity in a soft descent of its weight.” 
Sir Charles has admirably illustrated by sketches contrasting 
the fore extremity of the skeleton of the elephant with that of the 
camel, that the former is evidently constructed for strength, the 
latter for spring and speed : pillars of bones, like stone columns, 
standing in upright positions are evidently intended to support 
weight, movement being a secondary consideration ; on the other 
hand, bones arranged in regard to each other in zigzag or oblique 
directions, are adapted for movement and spring, ability to carry 
weight being the secondary consideration. This point has been 
