826 HORSE 16, after which the summits begin to assume a triangular form; the milk incisors are all shed before the age of five years. The saliva- ry glands, especially the parotid, are remark- ably developed ; the stomach is simple and ca- pacious ; the intestinal canal is long, but short in comparison with that of the ruminants ; but the colon is of enormous capacity, as also is the cfflcum, apparently occupying the greater portion of the abdominal cavity; the small intestine is about 56 ft. long, with a circum- ference of from 2 to 6 in. ; the caecum is 2 ft. long, and 2 ft. in circumference at the wi- dest part ; the colon and rectum are 21 ft. long, the former averaging 2 ft. in circumference ; the whole canal, therefore, is about 80 ft. long. The liver weighs between 4 and 5 Ibs., having no gall bladder, and the spleen 12 oz. ; the urinary bladder is small in comparison with the size of the animal, its circumference when moderately distended being about 1 ft. ; the mammary nipples are two, inguinal, and have at the base a hollow cavity which permits the accumulation of a considerable quantity of milk, which is often used by man as an article of diet, especially for invalids. The hoof of the horse presents an admirable adaptation to secure solidity and elasticity in an instrument of progression ; the whole exterior horny cov- ering, to which the shoe is attached, composed of modified epidermic structure, is a hollow cone truncated above, into which the coffin bone is received ; highest in front, it gradually diminishes backward, where it is suddenly turned inward, becoming mixed with the sole, supporting the under parts of the foot, and protecting the sole and the frog from too rough pressure against the ground ; this internal wall, called the " bars of the foot," by its sloping direction, distributes the weight of the body toward the sides of the hoof, with whose nu- merous perpendicular horny laminae interdigi- tate similar processes from the vascular sur- face of the coffin bone. In the triangular space in the centre of the foot is an elastic horny mass called the frog, its base connecting the posterior curves of the hoof, the sides uni- ted with the bar, and the point extending about to the centre of the sole ; on the sides are deep channels, to allow of its expansion and render the foot elastic ; its actual thickness in horn is not so great as farriers seem to think, from the freedom with which they use the paring knife ; in a well formed foot, the base of the frog ought to occupy one sixth of the circum- ference of the circle of the hoof; in the cen- tre of the frog is a horny conical cavity of con- siderable depth, which protects the partially cleft foot from further rupture, adds to the elasticity, secures a firmer hold on loose soils, and passing above into the substance of the sensitive frog serves to unite firmly the two halves of the foot, which are completely divi- ded in ruminants; this horny cone has been called the frogstay or bolt. The sensitive frog falls into the inverted arch of the horny frog, which are thus held mutually in place and preserved from external shock. The sole is an irregular plate of horn, closing up the lower opening of the foot, of an arched form, abutting everywhere against the sides of the wall, an- other contrivance for securing elasticity. The ! foot of the horse, therefore, though solid in front, is partially cleft behind, so that the terms solidungula and soUpeda cannot strictly be applied to it ; indeed a solid, continuous, un- yielding circle of horn would be very painful if not entirely useless as an instrument of ac- tive progression ; this beautiful structure, how- ever, is sadly interfered with in almost all methods of shoeing. Immediately under the hoof are extensive cartilages, attached to the last two bones, protecting the upper part of the structure and adding greatly to the elas- ticity of the foot, and permitting the move- ments of the coffin bone with the hoof; in old horses these cartilages may become partially ossified, and are then called ring-bones. Un- der the hoof is also a very sensitive and vas- cular layer, from which the hoof originates, analogous to the soft core of hollow horns and the matrix of nails. The eyes of the horse are large, and the sight is excellent, and capable of distinguishing objects by night ; the ears are large and very movable, and the sense of hear- ing is very acute, as in other timid and com- paratively defenceless animals; the sense of smell is also acute, as is seen in their selection of food and in the recognition of their masters ; the cutaneous sense is very fine, and the tactile powers of the movable lips exquisite. The food in a state of nature is exclusively vege- table. The time of gestation is about eleven months, and the foal in the domesticated state sucks six or seven months ; the sexes are sepa- rated at two years ; at three they may be bro- ken, and at four be ridden. The disposition of the horse is naturally gentle and confident, which qualities have made it the most useful of animals in all the arts of peace and war ; it is bold in the defence of its young, and occa- sionally an animal is vicious, either naturally or from bad treatment in youth. As we have horses varying in size from the Shetland pony to the Flanders dray horse, and in proportions from the thorough-bred racer to the Canadian cob, with every variety of color, so we find great diversity in their moral qualities ; some are bold, intelligent, or good-natured, and others timid, stupid, or cross, and by care or from neglect each of these qualities becomes the characteristic of a race. Their movements are many ; besides the walk, trot, gallop, and amble, pace, or rack, some horses gallop with the fore legs and trot witk the hind, others move each leg separately in succession, and others execute many artificial movements, the result of education. The horse is quick to perceive and has an excellent memory, two qualities which render his education easy ; he is capable also of deep and lasting attachment. The neigh or voice of the horse is well known,
