THE CIRCULATION OP CEREBRO-SPINAL SUBSTANCE. 



589 



with some function other than as a mere distributing center 

 is as likely; that this function should be to regulate the cir- 

 culation in the neurons, or groups of neurons with which it 

 is connected (as shown by the effects of poisons upon all struct- 

 ures thus connected), is strongly suggested by the fact that, 

 while the need of such a regulative system is evident, there 

 is no discernible or known organ or system of organs, directly 

 connected with the pial blood-vessels, other than these cells 

 to which this important function could be ascribed. The fol- 

 lowing conclusions, therefore, seem to us warranted: 



SEVEN CAUDATE NEUROGLIA FIBER-CELLS FROM THE HUMAN BRAIN- 

 CORTEX (FIRST LAYER). (Andriezen.) 



a, Tangential fiber-system. 6, Cell-bodies, c, Descending fiber-sys- 

 tem. The dotted line shows the limit between the first and second and the 

 second and third layers. 



The neuroglia-cells are the intermediaries between the general 

 circulation and the capillary system (neuroglia- fibrils) of the 

 brain-substance. The smooth stellate cell seems only to serve for 

 the equable distribution of the blood-plasma to the neurons, while 

 the mossy, or protoplasmic, cell presents the attributes of an organ 

 to which the function of inciting a group of neurons to action by 

 activating its blood-supply and of governing the quantity of nerv- 

 ous energy produced in these neurons can be ascribed. 



Judging from the admirable histological work of Andriezen 



