EXTERNAL STRUCTURE. 



67 



There is an evident intention in this division 

 of the head into so many bones. When the foetus 

 — the unborn foal — first begins to have Hfe, that 

 which afterwards becomes bone, is a mere jelly- 

 hke substance ; this is gradually changed into 

 a harder material — cartilage ; and, before the 

 birth of the animal, much of the cartilage is 

 taken away by vessels called absorbents, and 

 bone deposited in its stead. In flat bones, like 

 those of the head, this deposit takes place in 

 the centre, and rays or radiations of bone extend 

 thence in every direction. Then, by having so 

 many bones, there are so many centres of radia- 

 tion ; and, consequently, the formation of bone 

 is carried on so much the more rapidly, and per- 

 fected at the time when the necessities of the 

 animal require it. At the period of birth, how- 

 ever, this process is not completed, but the edges 

 of the bones remain somewhat sofl and pliant, 

 and therefore, in parturition, they yield a little 

 and overlap each other, and thus, by rendering 

 the birth more easy, they save the mother much 

 pain, and contribute to the safety of the foal. 

 Without a change in the form of the head, from a compression and yield- 

 ing of the bone of which it is composed, the animal could not be born. 



The first of these bones, or the first pair of them, occupying the broad 

 expanse of the forehead, are called the frontal hones, a a. They are united 

 together by a most curious and intricate dove-tailing, to defend from in- 

 jury the brain which lies beneath the upper part of them. Lower down, 

 and where the cavity of the nose is to be defended, their union is sufficient, 

 but far less complicated. The mechanism is here, as in every part of the 

 frame, and every part of the universe, wisely adjusted to the necessities 

 and wants of the animal. 



Few things more clearly indicate the breed or blood of the horse 

 than the form of the frontal bones. Who has not remarked the broad an- 

 gular forehead of the blood horse, giving him that beautiful expression of 

 intelligence and fire, and the face gradually tapering from the forehead to 

 the muzzle ; and then compared it with the large face of the cart or dray 

 horse, and the forehead scarcely wider than the face ? 



At /, between the frontal bones, is the pit or cavity above the eye, and 

 by the depth of which we form some idea of the age of the horse. There 

 is placed at the back of the eye, a considerable quantity of fatty substance, 

 on which the eye may revolve easily and without friction. In aged horses, 

 and in diseases attended with general loss of condition, much of this fat 

 disappears ; the eye becomes sunken, and the pit above the eye deepens. 

 It is said that some of the lower class of horse-dealers puncture the skin, 

 and, with a tobacco pipe or small tube, blow into the orifice, until the de- 

 pression is almost filled up. This operation is vulgarly called puffing the 

 glims, and, with the aid of a bishopped tooth, will give a false appearance 

 of youth, that will remain during many hours, and may deceive the unwary, 

 though the puffing may easily be detected by pressing on the part. 



Tliese bones, however, are not solid, but a considerable portion of them 

 is composed of two plates receding from each other, and leaving numerous 

 and large vacuities or cells. These vacuities are called ihef^ntal sinuses. 



