3O2 APPLIED PHYSIOLOGY 



and cerebrum. Each consists of gray matter con- 

 taining nerve cells, and of white matter made of 

 nerve threads. 



3. The medulla is like the spinal cord in that it gives off 



sensory and motor nerves. 



4. The medulla also originates impulses controlling res- 



piration and the contraction of arteries. 



5. The cerebellum adjusts the voluntary motor impulses 



of the brain, so that movements like balancing of 

 the body are done with precision. 



6. The optic tubercles are reflex centers for the eyes. 



7. The cerebrum forms four fifths of the brain, and con- 



sists of a puckered covering of gray matter over a 

 central mass of white nerve fibers. 



8. The cells of each part of the brain have a definite 



work to do. They receive sensory impressions, 

 send motor impulses, and think. 



9. The impressions of each cell remain as permanent 



memories which can be recalled at will. 



10. By means of speech, thought, sensory and motor 



impressions are conveyed to other persons and there 

 become memories as though they had actually been 

 experienced. 



11. In speech the centers for motion, sound, and sight 



all take part. 



12. There is a special center for producing the movements 



of the mouth in speech. 



13. The first stage of mind action is knowledge ; the next, 



emotion ; and the third, willing and acting. 



DEMONSTRATIONS 



126. Show as types the brains of a frog or fish ; of a hen ; and of a 

 fourfooted animal. A frog's, fish's, or chicken's brain can easily be 



