ANATOMY AND PHYSIOLOGY OF THE HOUSE’S TOOT. 429 
examinations have convinced me that the old idea was the 
correct one, and that this yellow substance is in reality fat 
enclosed in a network of areolar or connective tissue. This 
will at once become apparent to the histologist. Examined 
microscopically, it is found that the spaces are filled with 
masses of fat-vesicles, so close and numerous in places that 
the connective tissue can scarcely be perceived. This con- 
nective tissue is but loosely attached to the planes of inelastic 
fibres, and may be easily dissected from them. Towards the 
heels, where the spaces are widest, the masses of adipose 
vesicles are, of course, largest and most numerous, and as 
these spaces decrease on nearing the point or apex of the 
cushion they diminish in volume. Everywhere, however, 
their elements are the same ; large cells or vesicles, of vary- 
ing size, often containing nuclei, and meshes of connective 
tissue, in which yellow elastic as well as white fibres are 
interwoven. 
Blood-vessels, in well-injected specimens, are observed to 
pass along the planes of fibrous structure, sending off on their 
course numerous ramifying branches among the fat and con- 
nective tissue between them. 
This composition and arrangement of the plantar cushion 
admirably disposes it to play a most important part in the 
functions pertaining to the horse’s foot. The inelastic planes 
of fibres, whose meshes are filled with fat, are so placed as to 
resist a large amount of downward and backward pressure. 
By their interlacing and general disposition they, in one 
aspect, resemble the network enveloping a balloon, while in 
another they look like a number of netted hammocks laid 
on one another, and united by cords passing obliquely and 
perpendicularly between them, so as to compose a powerful 
suspensory bed, capable of withstanding a heavy superincum- 
bent load, as it hangs between its proper supports. Its 
intimate union with the lateral cartilages and the coronary 
and pedal bones ensures these supports. By means of its 
upper attachments to the small metacarpal bones, and to 
the posterior aspect of the fetlock and tendons, the fibres of 
the cushion are maintained in a sufficiently extended form, 
and kept in the position in which it may act most efficiently; 
at the same time, its lateral attachments assure its being 
moderately expanded behind and beneath the deep flexor 
tendon. The fat contained in its interstices completes it 
as a resilient apparatus. We know that masses or pads of 
fat are found in other situations in the body where elas- 
ticity, smoothness, softness of movement, and relief from 
pressure of more vitally endowed tissues, are required. 
