749 



irregular sustentacular cell with numerous hairs extending from the cellular body, and 

 one extremely long apical process directed toward the central brain regions. 12, 13 Glia 

 cells, with numerous long, and stout hairy processes from the bodies and thicser pro- 

 jections, probably transition forms between the sustentacular cells and cells of later 

 development. 14 Large mossy cells situated some distance from the ventricular wall. 



absence of lateral branches, until the periphery is nearly reached. 

 The peripheral rami are for the most part finer and shorter thaD 

 those of the chief class, and at times bear the rounded swellings at 

 their terminations. 



In the second sub-class (fig. 1, no. 3), the ependymal cell body 

 is large and distinct, sometimes very irregular in shape, and gives off 

 almost immediately branches, that subdivide at occasional intervals 

 until the margin is reached, where they also end in globular swellings. 



The third sub-class (fig. 1, no. 4), is only stained in part, and 

 may possibly be a further division of the last mentioned form, for the 

 main stems are only to be seen after the middle portion of the in- 

 fundibular wall is passed, and the connection between it and the 

 cellular body is therefore non-apparent. The fibres are sometimes 

 very coarse, at others fine, and always have a triangular or nodular 

 thickening at some variable point below the pial limit, from which 

 arises a spray of fine brancblets extending to the margin, which are 

 so closely set together, that usually when the limit is reached, they 

 only appear as a blackened mass. 



None of the branches of the ependymal cells anastomose, and with 

 the exception of the spray form, the branchings are comparatively in- 

 frequent, and always arise at nearly an obtuse angle from the main 

 stems. 



2) The second class is not met with in any abundance in the in- 

 fundibular wall, but more frequently in the inner than in the outer 

 half. The body of the cell is of moderate size (5, fig. 1) and from 

 it extend a multitude of very fine varicose processes, the longer ones 

 proceeding considerable distances from the cellular body. The general 

 effect produced by these numerous fine, almost straight processes is 

 to give a burrlike appearance to the cell. 



The Neuroglia Cells of the Ventricular Wall. 

 As we near the opening of the third ventricle into the infundi- 

 bular cavity, we find the ependymal cells assume a different form 

 from those already described. The cell-like mass at the base is now 

 very small (fig. 1, no. 6), the cells closely set together, so closely in- 

 deed, that they frequently appear to be fused into a single mass, out 



