170 THE NASAL BONES. 



The lachrymal duct is the channel through which the superfluous tears 

 are conveyed to the lower parts of the nostril. A long canal here com- 

 mences, and runs down and along the maxillary bone. It is very small, 

 and terminates in the cuticle, in order that the highly sensitive membrane 

 of the nose may not be excoriated by the tears occasionally rendered acri- 

 monious in inflammation of the eye. The oval termination of this duct is 

 easily brought into view by lifting the nostril. 



From some occasional acrimony of the tears, the lining of this duct 

 may be inflamed and thickened, or some foreign body, or some unctuous 

 matter from the ciliary glands, may insinuate itself into the duct, and the 

 fluid accumulates in the sac and distends it, and it bursts ; or the ulcer 

 eats through the integument, and there is a small fistulous opening beneath 

 the inner canthus of the eye, or there is a constant discharge from it. It 

 is this constant discharge that prevents the wound from healing. In some 

 cases the lachrymal bone is involved in the ulcerative process and becomes 

 carious. In the dog, and particularly in the smaller spaniel, the watery 

 eye, fistula lacrymalis,\s of no unusual occurrence. The fistula will be 

 recognised by a constant, although perhaps slight, discharge of pus. 



The structure and office of the velum palati, or veil of the palate, is in 

 the horse a perfect interposed section between the cavity of the mouth and 

 the nose, and cutting off all communication between them. In the dog, 

 who breathes almost entirely through the mouth, the velum palati is 

 smaller ; the tensor muscle, so beautifully described by Mr. Percivall, is 

 weak, but the circumflex one is stronger and more developed. When 

 coryza in the dog runs on to catarrh, and the membrane of the pharynx 

 partakes of the inflammation, the velum palati becomes inflamed and 

 thickened, but will not act as a perfect communication between the mouth 

 and the nose. When there is a defluxion from the nose, tinged by the 

 colour of the food, and particles of food mingle with it, we have one of 

 the worst symptoms that can present itself, because it proves the extent and 

 violence of the inflammation. 



In inflammatory affections of the membrane of the nose in the dog, we 

 often observe him snorting in a very peculiar way, with his head protrud- 

 ing, and the inspiration as forcible as the expiration. An emetic will 

 usually afford relief, or grain doses of the sulphate of copper. 



The Nasal Bones. The nasal bones of the dog (see fig. 2, in the 

 head of the dog, page 116) are very small, as they are in all carnivorous 

 animals. Instead of constituting the roof, and part of the outer wall 

 of the cavity, as in other animals, the nasal bones form only a portion, 

 and a small one, of the roof. 



The superior maxillaries here swell into importance, and constitute 

 the whole of the outer wall, and, sometimes, a part of the roof. The jaws 

 are the weapons of offence and defence ; and as much space as possible is 

 devoted to the insertion of those muscles that will enable the animal to 

 seize and to hold his prey. One of the most powerful of them, the 

 masseter, rises from the superior maxillary bone, and spreads over its 

 whole extent : therefore, that bone is developed, while the nasal bone is 

 compressed into a very small space. The substitution of a portion of 

 cartilage, instead of bone, at the posterior part of the orbital ring, in order 

 to give more play for the coracoid process of the posterior maxillary, round 

 which the temporal bone is wrapped, is a contrivance of the same nature. 



The scent of the dog is not sacrificed or impaired by the apparent diminu- 



