MUSCLE AND MIND. 379 



the extent of appropriating the food placed at its lips ; yet, 

 for the effective use of the arms and legs, months of training are 

 necessary ; while definite movements of the trunk, as in danc- 

 ing, bowing, etc., are acquired much later in life. It is also a 

 most significant fact that the center for the control of the various 

 and complex movements concerned in speech is limited to the 

 left side of the brain in right-handed 'persons — a few cases having 

 been recorded in which disease of the corresponding locality on 

 the right side of the brain has been followed by loss of speech in 

 the left-handed * — implying that the more frequent and intelligent 

 use of the muscles of the right hand and arm has had some con- 

 nection with the development of the faculty of speech. This is 

 corroborated by the fact that, among the lower animals, there is 

 little if any difference in the use of the anterior limbs, as there is 

 also absence of the faculty of speech — a factor of the highest im- 

 portance in mental development. 



Although the doctrine of localization has distinguished oppo- 

 nents, Prof. Goltz denying that either sensations or movements 

 have any special centers in the brain, and the late George Henry 

 Lewes opposing the idea to the extent of saying, " It is the whole 

 man who feels and thinks," nevertheless the doctrine is gaining 

 ground. At least two cases have been recorded of otherwise nor- 

 mal individuals in whom a congenital absence of the left hand 

 and a part of the arm was accompanied by a rudimentary condi- 

 tion of the corresponding convolution on the right side of the 

 brain, showing that the building up of these motor areas in the 

 brain is largely dependent on muscular exercise during the period 

 of growth. That the maintenance of their nutrition in the adult 

 is also to some extent dependent on muscular exercise is made 

 probable by the fact that wasting of the corresponding convolu- 

 tion has been found in a few instances after amputation of a limb. 

 Removal of the brain, slice by slice, in the lower animals is fol- 

 lowed by a corresponding reduction both of intelligence and of 

 power of voluntary movements which disappear together in about 

 an equal degree ; and every observer knows that in many cases 

 of brain disease intelligence and the power of voluntary move- 

 ment alike suffer in proportion to the extent of degradation of 

 brain substance. There is also no more conspicuous feature of 

 idiocy than its accompanying feeble, irregular, and uncoordinated 

 movements. Just what relations exist between the motor areas of 

 the brain and general intelligence is not a matter for dogmatic 

 assertion ; but that these centers form a part of the intellectual 

 machinery is undoubted, and the facts cited, without reference to 

 theories, may be regarded as proving my second thesis, viz., that 

 the systematic and regular use of the voluntary muscles of the body 



* Kiissmaul. 



