130 Dr. Frederick Walker Mott [April 21, 



rest of the brain is asleep, waiting to be awakened by the sensory- 

 impressions from without. The base of the brain and its stalk, which 

 is stained deeply purple, subserves the vegetative functions of life — 

 breathing, circulation of the blood, swallowing, digesting, etc. The 

 portions of the brain indicated by dots in the diagram (Fig. 5) form 

 receiving stations for all the nervous currents subserving special and 

 general sensibility ; but by the side of these receiving stations for 

 ingoing currents are developed transmitting stations for outgoing 

 currents to the muscles, consequently we are not surprised to find 

 in the diagram (Fig. 7) of a vertical slice of the brain of a child aged 

 three months, evidence of the formation of this outgoing tract to the 

 muscles. It is by this tract of fibres the infant commences to exercise 

 volitional movements. You will see, moreover, that there are now 

 developed fibres in the other regions of the brain ; these are for the 

 purpose of linking together and coordinating all the different sensory 

 areas — association fibres as they are called. You will, moreover, see 

 that the greater part of the surface of the brain is made up of these 

 association systems, and in these regions there are, according to 

 Flechsig, no sensory and motor nervous elements. Flechsig terms 

 these portions of the brain association centres. They are situated in 

 the frontal region, the temporal, occipital, parietal, and a small lobe 

 which lies at the back of the large sylvian fissure called the island. 

 Flechsig states that it is in these association centres that every 

 sensation perceived leaves an ineffaceable imprint which constitutes 

 memory. It is there in these higher centres that visual, auditory, 

 tactile-motor and other sensations meet and fuse together. It is 

 there they are compared one with another and to previous sensa- 

 tions. It is there the mind finds the indispensable elements for all 

 the acts of intellectual or physical life. They form, in fact, the 

 anatomical substratum of human experience, knowledge, language, 

 sentiments and emotions. From the association centres nerve cur- 

 rents pass into the sensory sphere, controlling the lower centres of 

 sensation and movement. It is generally believed that great develop- 

 ment of the frontal region of the brain indicates high intellectual 

 power. Observations have, however, been made which would seem 

 to point to the great posterior lobe being connected with the higher 

 intellectual functions of the mind. The brains of eighteen very dis- 

 tinguished men deceased were examined, and the essential features 

 which were noted were extraordinary convolutional complexity and 

 development of the posterior lobe. Eecently the skulls of Beethoven 

 and Bach have been examined, and measurements indicate that this 

 portion of their brains must have had a great development. 



In the nervous system we have three systems of nervous units or 

 neurones. I will call your attention to the accompanying diagram 

 (fc'ig. 8) which shows these systems, namely — 1. Ingoing sensory; 

 2. Outgoing motor ; and 3. Association. The latter form the great 

 bulk of the nervous units of the brain. You will observe that in the 



