THE MECHANISM OF LIFE 



583 



cord, alone possess in their one nerve-process a sensory path, which 

 receives impulses from the periphery in the form of external stimuli 

 and transmits them to the cell-bodies ; thence the impulses are 

 continued through the other nerve-process to other neurons. 

 Hence, as regards the body of the ganglion-cell to which they 

 belong, the dendrites conduct always centripetally, the nerve- 

 processes in the unipolar ganglion-cells always centrifugally. The 

 greater or smaller number of the dendrites of a ganglion-cell 



Dendrites. ' ' 



Cell-body. 



Nerve-process. 



FIG. 283. Cell of Purkiiije from the grey cortical layer of the brain. (From Stohr.) 



appears to depend upon the question, with how many other neurons 

 the ganglion-cell is in connection. Thus, the cells of Purkinje 

 in the grey cortical layer of the brain, in which the most complex 

 psychic processes are believed to be localised, have an extraordin- 

 arily richly developed system of dendrites (Figs. 283 and 284). 

 The nerve-fibres of one ganglion-cell pass to the dendrites 

 of another ganglion-cell. It is here a noteworthy fact, that, 

 according to the later investigations, the connection between the 

 two takes place not by direct continuity of their substance, or, as 



