48 SKETCH OF THE ANATOMY OF THE HORSE. 



senses are conveyed to the brain, and is the means by which orders from 

 the brain are transmitted to the muscles of the hmbs. 



We may divide the brain into the medulla oblongata, the cerebellum, 

 and the cerebrum. 



The medulla oblongata connects the two other portions of the brain 

 with the spinal cord. It is the nervous centre of the function of breathing. 

 Animals, for purposes of experiment, have had their spinal cord and the 

 whole of their brain, except the medulla, removed, and yet they have 

 continued to breathe and live. But when the medulla is injured, death 

 from inability to breathe, at once ensues. 



The cerebellum is the organ of muscular sense and of combined 

 muscular effort. By its muscular sense an animal can tell, from ex- 

 perience, the amount of muscular force required in performing its 

 various voluntary movements. We cannot, by an effort of will, move 

 any one particular muscle of our body ; but we can cause our limbs to 

 perform definite movements which require the combined action of 

 various muscles, and which are under the control of the cerebellum. 



The cerebrum is the organ of intellect, thought, and will. " Removal 

 of the cerebrum in the lower animals appears to reduce them to a con- 

 dition of a mechanism without spontaneity. A pigeon from which the 

 cerebrum has been removed will remain motionless and apparently 

 unconscious unless disturbed. When disturbed in any way, it soon re- 

 covers its former position. When thrown into the air it flies " [Kirkes' 

 Physiology). The cerebrum appears to be the organ in which a conclusion 

 or thought is formed from a message or a number of messages proceeding 

 from the senses. If, for instance, a man standing near a horse's hind- 

 quarters touches him with a stick, and if the animal kicks the stick, he 

 will perform, more or less, a reflex action. If, however, the horse recog- 

 nises who the real offending party is, and kicks the man, he will have drawn 

 a conclusion from the message received from his sense of feeling and of 

 sight, and will have acted on such conclusion, which would be, more or 

 less, an effort of reason. 



Among the intellectual faculties, of which the cerebrum is the special 

 organ, we have, prominently, reason and memory. Although the horse 

 is greatly deficient in the former, which is by far the higher faculty of 

 the two, he possesses the latter in special excellence. 



The cerebrum is placed immediately underneath the forehead, at the 

 centre of which it is covered by only a thin plate of bone. The cere- 

 bellum, which is a great deal smaller than the cerebrum, lies below the 

 top of the head (occipital crest), when the face is held at an angle of 

 about 45° with the ground. 



The proportion which the weight of the brain bears to that of the 

 spinal cord, is a fair guide to the intellectual capacity of an animal. 

 The following is a list of the average number of times the brain is 



