146 ANATOMY AND DISEASES OF THE NOSE AND MOUTH. 



are SD aller, and narrower, and more regular, than the upper ones. They are placed 

 horizc fltally in either jaw; but in the lower the higher side is within, and shelving 

 gradu illy outward ; in the upper jaw the higher side is without, and shelving inward, 

 and tl us the grinding motion is most advantageously performed. There is also an evi- 

 dent r ifference in me appearance and structure of each of the grinders, so that a carefi:! 

 obsei ret could tell to which jaw every one belonged, and what situation it occupied. 

 At the completion of the first year, a fourth grinder usually comes up, and the year- 

 ling "ias then, or soon afterwards, six nippers, and four grinders abovo and below ii 

 each jaw, which, with the alteration in the appearance of the nippers that we have 

 just described, will enable us to calculate nearly the age of the foal, subject to some 

 variations arising from the period of weaning, and the nature of the food. 



At the age of one year and a-half, the mark in the 

 central nippers will be much shorter and fainter ; thai 

 in the two other pairs will have undergone an evident 

 change, and all the nippers will be flat. 



At two years this will be more manifest. The ac- 

 companying cut deserves attention, as giving an accu- 

 rate representation of the nippers in the lower jaw of 

 a two-years-old colt. 



About this period a fifth grinder will appear, and now, 

 likewise, will commence anotl 



another process. The firs! 



teeth are adapted to the size and wants of the younu 

 animal. They are sufficiently large to occupy and fill 

 the colt's jaws ; but when these bones have expanded 

 with the increasing growth of the animal, the teeth are separated too far from each 

 other to be useful, and another and larger set is required. Evident provision is made 

 for them, even before the colt foaled. In cavities in the jaw, beneath the first and 

 temporary teeth, are to be seen the rudiments of a second and permanent set. These 

 gradually increase, some with greater rapidity than others, and, pressing upon the 

 roots or fangs of the first teeth, do not, as would be imagined, force out the formei 

 ones, but the portion pressed upon gradually disappears. It is absorbed taken up 

 and carried away, by numerous minute vessels, whose office it is to get rid of the 

 worn-out or useless part of the system. This absorption continues to proceed as the 

 second teeth grow and press upwards, until the whole of the fang is gone, and f,he 

 crown of the tooth, or that part of it which was above the gum, having no Conger 

 firm hold, drops out, and the second teeth appear, larger and stronger and permanent. 

 In a few instances, however, the second teeth do not rise immediately under the tem- 

 porary or milk teeth, but somewhat by their side ; and then, instead of this gradual 

 process of absorption and disappearance from the point of the root upwards, the root 

 being compressed sideways, diminishes throughout its whole bulk. The crown ot 

 the tooth diminishes with the root, and the whole is pushed out of its place, to the 

 fore part of the first grinder, and remains for a considerable time, under the .name of 

 a wolf "s tooth, causing swelling and soreness of the gums, and frequently wounding the 

 cheeks. They would be gradually quite absorbed, but the process might be slow 

 and the annoyance would be great, and, therefore, they are extracted. 



The change of the teeth commences in those which earliest appeared, and there- 

 fore, the front or first grinder gives way at the age of two years, and is succeeded by 

 a larger and permanent tooth. 



During the period between the falling out of the central milk nippers, and the 

 coming up of the permanent ones, the colt, having a broken mouth, may have some 

 difficulty in grazing. If he should fall away considerably in condition, he should be 

 fed with mashes and corn, of cut meat. 



The next cut will represent a thee-years-old mo Jth. The central teeth are larger 

 than the others, with two grooves at the outer convex surface, and the mark is long 

 narrow, deep and black. Not having yet attained their full growth, they are rather 

 lower than the others. The mark in the two next nippers is nearly worn out, and it 

 IB wearing away in the coiner nippers. Is it possible to give this mouth to an early 

 iwo-years-old? The ages of all horses used to be reckoned from May, but some ar 

 (baled even so ear'y as January, and being actually four months over the two 7 ears 



