FUNCTIONS OF THE BRAIN. 



35 



followed months later by contracture of the muscles, as in 

 man after inveterate hemiplegia.* According to Schaefer 

 and Horsley, the trunk-muscles also become paralyzed after 

 destruction of the marginal convolution on both sides (see 

 Fig. 7). These differences between dogs and monkeys show 

 the danger of drawing general conclusions from experiments 

 done on any one sort of animal. I subjoin the figures given 

 by the last-named authors of the motor regions in the 

 monkey's brain. f 



Fig. 7.— Left Hemisphere of Monkey's Brain. Mesial Surface. 



In man we are necessarily reduced to the observation 

 •post-mortem of cortical ablations produced by accident or 

 disease (tumor, hemorrhage, softening, etc.). What results 

 during life from such conditions is either localized spasm, 

 or palsy of certain muscles of the opposite side. The cor- 

 tical regions which invariably produce these results are 

 homologous with those which we have just been study- 

 ing in the dog, cat, sre, etc. Figs. 8 and 9 show the result of 



* 'Hemiplegia' means one-sided palsy. 



f Philosophical Transactions, vol. 179, pp. 6. 10 (1888). In a later paper 

 (Und. p. 205) Messrs. Beevor and Horsley go into the localization still more 

 minutely, showing spots from which single muscles or single digits can be 

 made to contract. 



