74- IXSTINTT, REASON, ETC. 



Now, to sec how this is all brought about, wo must 

 advert briefly to the various functions of the different parts of 

 the brain. 



The spinal marrow with its extension into the skull, the 

 medulla oblongata is concerned in all those acts that are of a 

 purely reflex character, such -as the beating of the heart, 

 prehension and digestion of food, &c, <fcc., necessary to its 

 existence as a living organism. The very lowest of the 

 animal kingdom possess these functions in common with 

 man and the higher animals, and it is shared by embryos in 

 their earliest stages. These acts are automatic, and take 

 place immediately the stimulus is received. 



The next two series of actions, which require for their 

 fulfilment the cerebellum and cerebrum, though the messages 

 to fulfil them are not received direct from the outside world, 

 are governed by them. All these acts require a period of 

 delay or tension from the receipt of the impression to the 

 determination of the consequent movement. This implies 

 consciousness. Diminish this period of tension, and there is 

 a consequent diminution in the vividness of the consciousness. 

 Take the various acts performed by a trained mechanic. 

 While he is an apprentice he must bind the whole of his 

 thoughts to the task in hand, and he is consequently slow in 

 his muscular adjustments, till the time comes when his saw, 

 plane or file, works automatically, while he converses on other 

 subjects. Conscious acts become reflex. 



" Consciousness " implies perpetual discrimination, or the 

 recognition of likenesses and differences, and this is impossible 

 unless impressions persist long enough to be compared with 

 one another. 



It is the surplus of molecular disturbance remaining in 

 the cerebellum and cerebrum, and reflected back and forth 

 among the cells and fibres of these higher nerve centres, 

 that affords the physical condition for the manifestation of 

 consciousness. 



Thus we see the cerebrum and cerebellum are the store- 

 houses of experiences. 



The cerebellum is concerned in the accomplishment of 

 co-ordinate muscular adjustments, the cerebrum in forming 

 rational ideas. 



It is in the direction of increase of cerebral surface that 

 Evolution is tending. 



And now, ladies and gentlemen, I must bring my paper 

 to a close. I am aware that my case must receive from you 

 the verdict of the Scotch courts of law " not proven." Even 



