97 



cerebellum. The spinal cord, unlike the brain, is formed of an outer white 

 portion and a central grey portion, the former made up of fibres, and the latter 

 of cells and fibres. 



The two figures placed "at the beginning of this chapter are taken by the 

 kind permission of Dr. J. McFadyean, M.I>., CM., B.Sc, from his valuable 

 work on the "Anatomy of the Horse." They will give our readers a ver)- 

 good idea of the superior and inferior aspects of the horse's brain. It will 

 be seen that the encephalon, or brain of the horse, is an ovoid mass, which, 

 when viewed on its superior surface, shews most posteriorly the continuaticn 

 of the spinal cord, called the medulla oblongata, and in front of thir, 

 the superior surfaces of the middle and two lateral lobes of the cerebellum. 

 In front of the cerebellum are seen the two large cerebral hemispheres, 

 which are separated from the cerebellum by a deep trans\erse fissure, 

 into which the tentorium cerebelli passes. 



On the inferior aspect, we see that the medulla oblongata is prolonged 

 beneath the cerebellum, and then becomes continuous with the cerebntl 

 hemispheres, by means of the crura cerbri, which are bounded in front by 

 the two thick white cords, the optic nerves. The brain may be said to 

 consist of three portions: (i) The isthmus of th: cncephahvi /the 

 ])rolongation of the spinal cord) ; (2) The cerebellum ; (3) The cerebrum. 



For further details, vide Dr. McFadyean's work, or Chauveau's. 

 Comparati\e Anatom}\ 



STRINGHALT. 



After these preliminary remarks, we may at once proceed to describe 

 the diseases of the nervous system of the horse, commencing with stringhah.. 

 Stringhalt consists in involuntary convulsive motions of the muscles, 

 generally those of one or both hind legs ; but occasionally it is 

 seen in the fore legs also. Generally speaking, however, it is confined to one 

 of the hind legs ; more rarely affecting both of them. Stringhalt is a 

 common affection of the horse, and of necessity constitutes unsoundness, 

 although many horses aftected with this disorder are able to do their work 

 exceedingly well. We have a chestnut horse at the present time, and have 

 seen numbers of others, which do their work every whit as well as horses 

 in all respects healthy. In severe cases, stringhalt is evident to the observer 

 at every step taken by the animal, while in cases not so marked, the affection 

 can only be noticed at longer or shorter intervals. "The animal may proceed 

 a few yards in a normal manner, and then suddenly snatch one or both of his 

 hind legs from the ground convulsively, with a sudden jerk, and bring it 

 down again with unusual force. 



Stringhalt often becomes worse as time passes on, but it may remain in 

 pretty much the same condition for some years. We have often observed 

 that it improves as the general health and condition of the animal improve, 

 and becomes worse when the animal is worked too hard, or when from any 

 other cause he is out of condition. As, in many instances, stringhalt 

 H 



