THE CONQUEST OF DISEASE 



of the monkey is so closely analogous to that of 

 man that localization findings in one are of 

 much help in understanding the other. Munk, 

 Schaefer, and Sherrington also contributed the 

 results of their animal studies to this knowl- 

 edge. It was found that a certain area of the 

 cortex of the brain originates the impulses 

 which cause the motion of certain muscles. The 

 place of origin in the brain of the whole nerve 

 supply of the muscular system is now pretty 

 well known. 



In the lower animals these centers are 

 located in the basilar ganglia ; but as we ascend 

 in the intellectual scale the motor areas seem 

 to be transferred to the cortex and come more 

 and more under the intellectual control. The 

 paths of the nerves from these centers through 

 the base of the brain to the muscles which they 

 control have been worked out. Now when a 

 person presents paralysis of certain muscles or 

 groups of muscles, whether it is due to apo- 

 plexy, tumor, inflammation, or injury we are 

 enabled to know the location and extent of the 

 damage. So fully has this knowledge been 

 worked out that the speech center and the 

 center which controls the muscles of phonation, 

 with the paths of their nerves, are known. The 



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