THE NERVOUS SYSTEM 343 



motor chains, and apparently its influence is universal. It 

 regulates tone, reflex action, voluntary action. There is no 

 part of the nervous system over which its control is not felt. 

 By its action on the apparatus which binds the infinity of 

 receptors which the body contains to its muscle-fibres and 

 other effectors, it unifies the body. The cerebrum, as we 

 shall see, is the organ which unifies the personality. In the 

 progress of evolution two functions which were originally com- 

 bined have, for convenience of concentration, been divorced. 

 The great brain has been set free from the more mechanical 

 part of the work. That it can perform the functions of the 

 cerebellum as well as its own is proved in cases of congenital 

 deficiency of that organ. In several instances malformation, 

 amounting to a very considerable reduction in the size of the 

 cerebellum, was not detected until after death, there being no 

 symptoms of a sufficiently pronounced character to call 

 attention to it during life. 



The Cerebrum. All observations made on the great brain 

 prior to 1870 showed it as absolutely inexcitable. Surgeons 

 and physiologists agreed that cutting, burning, passing electric 

 currents through its substance, neither yielded evidence of 

 sensation nor movement of any part of the body. Concerning 

 its structure little was known beyond the fact that whereas 

 the grey matter, or cortex, which covers its surface contains 

 nerve-cells, only fibres are to be found in the white matter 

 which constitutes the greater part of its bulk. It seemed a 

 hopeless task to attempt to make anything out of a mass of 

 tissue so uniform in constitution and so irresponsive to experi- 

 ment. Removing portions of it appeared to cause a general 

 dulling of the intellect without loss of any particular mental 

 quality. Physiologists, therefore, spoke of the cerebrum 

 as " functioning as a whole." Phrenologists, having classified 

 the various phases of mental activity as " faculties," dis- 

 covered " bumps " on the surface of the skull which they 

 correlated with the possession of the several faculties in a 

 marked degree. They parcelled out the brain in organs con- 

 cerned with different kinds of thought ; but their localization 

 of function was anatomically as baseless as their classification 

 of the various aspects of mind, viewed as a system of philo- 

 sophy, was absurd. In 1870 it was announced that electrical 



