122 THE SPINAL CORD AND CEREBELLUM 



cially numerous, as they are in this instance — and as 

 they are in, perhaps, an even more marked degree 

 in the cerebellum — when they, so to speak, envelop 

 the cell, as in Clarke's column and in the case of 

 Purkinje's giant cerebellar cells — there is evidently a 

 special meaning in this mode of distribution. The 

 large cells thus enwrapped occupy a central position : 

 they must perform a central function. When they 

 vibrate, the intensity of vibration of all the smaller 

 cells connected with them is suddenly increased. The 

 conditions which we have before us do not admit of 

 any other interpretation. The large cell may send 

 forth its impulse along its main fibre or axon, but as 

 soon as it becomes active the smaller cells with which 

 it is connected must necessarily vibrate more power- 

 fully than before. It matters not, indeed, whether 

 the fibres connecting the latter wiiA the former are 

 afferent or efferent channels, for in the one case the 

 large cell would, one might su] pose, act as an attrac- 

 tive centre, whilst in the other event its action might 

 be of a radiating or propulsive kind. To the large 

 cells, therefore, on account of i their relations to the 

 smaller ones, we are justifiq'd in giving the title 



Increase ' increase of impulse ' cells. . 



cells. One of the primary conditions' of organic life is that 



functional activity is never equal throughout the whole 

 organism. It varies as to place, as to time, and as to 

 degree or intensity. This condition is so universal, 

 and so essentially a part of our nature as that of 

 every other living creature, that we are somewhat 



