OUTLINE OF THE STRUCTURE OF THE HORSE. 51 



9 The cartilage covering the entrance into the eustachian tube, or communi- 

 cation between the mouth and internal part of the ear. 



10 The oesophagus, or gullet. 



11 The cricoid {ring-like) cartilage of the larynx, below and behind the thyroid. 



12 Muscle of the neck, covered by the membrane of the back part of the mouth. 



All the agents concerned in the existence and movements 

 of animal life would be utterly inert and powerless, had they 

 not been combined with some motive power to excite and 

 regulate their action. Such a motive powder the Creator has 

 provided in that wonderful organization the nervous system, 

 consisting of the brain, the spinal cord, and the nerves. 



There are many things difficult to be understood in regard 

 to the nervous system and its operations. Some of these are 

 too deep for the wisest and most learned to fathom, much 

 less to satisfactorily explain. But the careful reader can get 

 a good general idea of the structure and offices of* its differ- 

 ent parts by means of the descriptions which we shall give, 

 aided by the foregoing cut. Perhaps we can do no better 

 than to quote from Youatt : 



"The brain of the horse corresponds with the cavity in 

 which it is placed. It is* a flattened oval. It is divided into 

 two parts, one much larger than the other — the cerebrum^ or 

 hrain^ (see m, in cut,) and the cerebellum, or little brain,, (see 

 n,) In the human being, the cerebrum is above the cere- 

 bellum ; in the quadruped, it is below ; and yet in both they 

 retain the same relative situation. [This arises from the fact 

 that in man the head surmounts the body perpendicularly, 

 while in quadrupeds its position is relatively slanting.] 



"He who for the first time examines the brain of the 

 horse will be struck with its comparatively diminutive size. 

 The human being is not, generally speaking, more than one- 

 half or one-third of the size and weight of the horse,* yet 

 the brain of the biped is twice as large and as heavy as that 

 of the quadruped. If it had been the brain of the ox that 

 had been here exposed, instead of that of the horse, it would 



* This is a singularly weak statement for so careful a writer. The weight of 

 the horse's body is at least eight times that of a man's. 



