THE CIRCULATION OP CEREBRO-SPINAL SUBSTANCE. 585 



granular contour, as if a fine moss constituted the protoplasmic 

 processes. . . . Further, by one or more of their coarser 

 processes the protoplasmic cells are attached to the perivascular 

 sheaths. The figure [on the opposite page] shows the cell with 

 two such vascular processes, each attacked to the vessel by a conical 

 disk-like expansion ('foot')." 



We could hardly produce stronger evidence than this in 

 favor of our view that neuroglia-cells and fibrils are channels 

 for blood. Bearing directly upon the question in point, how- 

 ever, is the fact that this cell, as indicated by its gemmules and 

 its dendritic appearance, must be supplied with myelin. The 

 association of this myelin with the blood-plasma in transit at 

 this point i.e., so close to the blood-vessel seems suggestive, 

 for, if the illustration is closely examined, dendrites are not 

 alone found around the cell, but also fibrils, which start from 

 various parts of these dendrites. That these protoplasmic neu- 

 roglia-cells are directly connected with the blood-vessels so 

 as to admit plasma is demonstrated by the fact that they also 

 take part in the engorgement of neuroglia structures that fol- 

 low poisoning. "The bodies of the mossy neuroglia-cells," 

 writes Berkley, alluding to the effects of ricin poisoning, "are 

 larger than normal, rounded, sometimes globular in outline, 

 and the tentacles are thickened and knotty. There are general 

 evidences that these structures of the lymphatic system are 

 undergoing modifications of a pathological nature." We have 

 already stated that this "lymph" was, according to our view, 

 its next o' kin: i.e., blood-plasma. 



Eeferring to the paper from which we have just quoted, 

 Andriezen remarks 59 : "We also stated at the time that the 

 evidence of staining with Golgi's method shows us a system 

 of lymph-spaces surrounding the cell-body and its branches. 

 Careful and fresh observation confirm us in this opinion, viz.: 

 that there is an exceedingly fine system of canaliculi and lymph- 

 spaces surrounding the body, and dendritic processes of the 

 protoplasmic glia-cell, and directly continuous with the peri- 

 vascular lymph-spaces." If the annexed sketches by Andriezen 

 are now examined and interpreted from our standpoint, addi- 



69 Andriezen: Brain, Winter, 



