THE BRAIN. 43 



The medulla oblongata connects the other two 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 were the medulla injured, death from inability to 

 breathe would at once ensue. 



The cerebdhcm appears to be the organ of viuscular scfisc and of combined 

 muscular effort. By its muscular sense the animal can tell, from experience, 

 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 will 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 condition 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 recovers its former position. 

 When thrown into the air it flies " {Kirke's Physiology). The cerebrum 

 appears to be the organ in which a conclusion or thought is formed from a 

 message or 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 recognises 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 certainly be 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 cerebellum, 

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

 (occipital crest) top of the head, 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 regarded by many as a fair guide to the intellectual 

 capacity of an animal. The following is a list of a few examples of the 



