c Theory. 



658 



9 and 10. On Brocas Convolution. Center for lips and tongue in articulation. Its 

 disease causes aphasia. Beneath and a little in front of the figure 9 is the Island of Reil, 

 Center of speech. 



11 Center for the platysma and risorius muscles in the retraction of the angle of the 

 mouch. ( See fig. 66.) 



12. Center for lateral movement for head and eyes with elevation of eyelids and dila- 

 tion of the pupil. 



a, 6, c, d.On ascending parietal convolution. Centers for movement of fingers and 

 wrist. 



13, 13' .On the supra marginal lobule and angular gyrus. Centers of Vision, which 

 also embrace additional portions of the occipital lobe. 



14. On superior tempero-sphenoidal convolution. Centers of Hearing. 



15. (Fig. 361.) On exterior aspect of Uncinate Gyrus. Region of Smell. (See fig. 367.) 



20. (Fig. 361.) Shaded area in temporal lobe in sympathy with region of smell and 

 taste. Destruction of this region in the monkey causes loss of smell on the same side, 

 and also affects the sense of taste. 



FIG. 362. 

 Human Brain. ( References same as for 361.) 



A comparison of the figures and descriptions shows that there is a 

 practical identity between the brains of monkeys and men, as to their 

 sensory and motor functions. The same parts receive impressions from 

 the eye, ear, organs of smell, &c. , and identical parts are concerned in 

 despatching the motor stimuli to the various muscular parts. Between 

 these sensory and motor areas of the brain and aside from them are con- 

 siderable tracts whose office it is to condense and co-ordinate the differ- 

 ent sensory stimuli. The more cells there are that are employed in this 

 business, the more consistent, positive and powerful will the resulting 

 motor action be. The absence of such cells would leave the individual 

 subject to each sensory impulse as fast as it came up. Everything 

 would be done without reflection, and the cerebrum without these inter- 

 medial condensing and balancing organs, would be such a machine as 

 the spinal cord or the medulla oblongata. 



Of the considerable areas, both in the frontal and the posterior lobes, 



