114 THE SENSORIAL FUNCTION. 



dangerous ; he kicks, plunges, and, half conscious and half unconscious, he 

 endeavours to do all the mischief that he can. The disease is now evidently 

 combined with, or is essentially, inflammation of the brain. It is distinguished 

 from madness by this half-consciousness, and also by his being more disposed 

 to bite than he is in pure phrenitis. 



The disease is usually fatal. It rarely lasts more than eight-and-forty hours. 



The post-mortem appearances are, great inflammation of the brain with fre- 

 quent effusions of blood. The sinuses are sometimes filled with coagulated 

 blood. The brain seems to be affected just in proportion to the violence which 

 the animal has exhibited. 



The treatment should consist of copious bleeding, application of ice to the 

 head, blistering the head, and physic. The trephine is scarcely admissible, from 

 the danger of producing greater irritation. 



Sometimes the disease assumes a more chronic form. There is ulceration of 

 the membrane, but not cerebral affection. A purulent discharge then appears 

 from the nose, evidently not of a glanderous character, and none of the sub- 

 maxillary glands are enlarged. In both the acute and chronic form it is usually 

 confined to one sinus. We are indebted to the late Mr. John Field for the 

 principal knowledge that we have of this disease *. The inner plate of the 

 frontal bone covers a considerable portion of the anterior part of the brain, and 

 it is studded with depressions corresponding with irregularities on the surface 

 of the brain. 



Immediately above the frontal, and extending from the frontal to the poll, 

 are the parietal bones. They are two, united together by a suture when 

 the animal is young, but that suture soon becoming obliterated. They have the 

 occipital, g, p. 110, above, the frontals, a a, below, and the temporals, d d, on 

 either side. They are of a closer and harder texture than the frontals, because 

 they are more exposed to injury, and more concerned in defending the brain. 



A very small portion only of the parietals is naked, and that is composed of 

 bone even harder than the other part, and with an additional layer of bone rising 

 in the form of a crest or ridge externally. Every other part of these bones is 

 covered by a thick mass of muscle, the temporal muscle, which is principally 

 concerned in chewing the food, but which likewise, by its yielding resistance, 

 speedily and effectually breaks the force of the most violent blow. A wool- 

 pack hung over the wall of a fortress, when the enemy is battering to effect a 

 breach, renders the heaviest artillery almost harmless. So the yielding resist- 

 ance of the temporal muscle affords a sure defence to the brain, however sudden 

 or violent may be the blow which falls on the parietal. These benevolent pro- 

 visions will not be disregarded by the reflecting mind. 



On the side of the head, and under the parietals (d d, p. 110) are the tempo- 

 ral-bones, one on each side,//. These again are divided into two parts, or consist 

 of two distinct bones ; the petrous portion, so called from its great or stony hard- 

 ness, and containing the wonderful mechanism of the ear, and the squamous portion 

 from the appearance of its union with the parietal, overlapping it like a great scale. 



From the latter there projects a portion of bone, e, which unites with the frontal, 

 and forms a strong arch — the zygomatic — distinctly to be felt at the side of the 

 head immediately above the eye. This arch is designed to protect the upper part 

 of the lower jaw, the motion of which may very plainly be seen beneath it when 

 the horse is feeding. It is very strong, and it ought to be, for if it were depressed 

 or forced inward, the horse would starve. There is one species of violence 

 which causes this arch to require no common strength; and that is, the brutal 

 manner in which the collar is often forced over the head. 



* The Veterinarian, vol. iv., p. 198. 



