ANATOMY AND PHYSIOLOGY OP THE HORSE’S FOOT. 251 
these types of feet will undergo changes in form and consistency, 
which would allow them to contend successfully with the altered 
conditions they should have to encounter. Transplanted from 
a congenial climate, with its warm, dry atmosphere, to a low, 
humid region, the narrow, hollow-soled hoof, under the influ- 
ence of such physical agencies as moisture and soft soil, gra- 
dually assumes the shape of that belonging to the massive 
animal just referred to. The cause of this transformation 
may be justly ascribed to the aqueous character of the food, 
and the softness and want of cohesion which the horn com- 
posing the hoof acquires, and which renders it less able to 
support the weight ; the muddy ground also plays an import- 
ant part, for the foot, sinking deeply into it, rests on a plane that 
inclines outwards in every direction, and this acts powerfully 
in dilating the circumference of the hoof, this dilatation 
being again accelerated by the large amount of pressure the 
frog receives. This effect of the soil is, of course, all the 
more marked as the plantar surface is concave. The wide, 
clumsy-looking, flat foot, removed from the marsh to a dry 
which, though it must have attracted attention, I have never seen mentioned 
by naturalists. It is equivalent to an arrangement that distinguishes the 
foot of the reindeer from that of the stag and the antelope. In them the 
hoofs, being constructed for lightness and flight, are compact and vertical ; 
but in the reindeer the joints of the tarsal bones admit of lateral expansion, 
and the broad hoofs curve upwards in front, while the secondary ones 
behind, which are but slightly developed in the fallow-deer and others of 
the same family, are prolonged till, in certain positions, they are capable of 
being applied to the ground, thus adding to the circumference and sustaining 
power of the foot. It has been usually suggested, as the probable design of 
this structure, that it is to enable the reindeer to shovel under the snow in 
order to reach the lichens beneath it ; but I apprehend that another use of it 
has been overlooked, that of facilitating its movements in search of food by 
increasing the difficulty of its sinking in the snow. A formation precisely 
analogous in the buffalo seems to point to a corresponding design. The ox, 
whose life is spent on firm ground, has the bones of the foot so constructed 
as to afford the most solid support to an animal of its great weight ; but in 
the buffalo, which delights in the morasses or the margins of pools and rivers, 
the formation of the foot resembles that of the reindeer. The tarsi in front 
extend almost horizontally from the upright bones of the leg, and spread 
widely on touching the ground ; the hoofs arc flattened and broad, with the 
extremities turned upwards; and the false hoofs descend behind till, in 
walking, they make a clattering sound. In traversing the marshes this com- 
bination of abnormal incidents serves to give extraordinary breadth to the 
foot, and not only prevents the buffalo from sinking inconveniently in soft 
ground, but at the same time presents no obstacle to the withdrawal of his 
foot from the mud.” — ‘ Ceylon,’ vol. i,p. 156. 
Professor Owen has commented upon a similar conformation in the elk 
and bison. When these creatures inhabit swampy localities, the second and 
fifth digits become largely expanded ; while in the camel and dromedary, 
which traverse arid deserts, they are nearly obliterated. — ‘Comparative 
Anatomy and Physiology of Vertebrates.’ 
