G. Carl Huber 47 



them, however, run vertically, that is, parallel to the nerve-fibers. 

 These processes are well stained by the chrome-silver method. The 

 fibrils differ morphologically, physically and chemically from the cell- 

 processes. They are, however, developed from the protoplasm of the 

 cells and lie partly in and partly on the protoplasm and have a direc- 

 tion which in the main is opposite to that of the cell processes. For the 

 most part these fibrils, the length of which is unknown, are emanci- 

 pated from the cell-bodies. The fibrils differ in thickness and probably 

 do not anastomose. These are the fibrils which are so clearly brought 

 out by the Weigert method." 



Erik Miiller's " Studies on Neuroglia " may also be mentioned in 

 this connection. His observations were made on tissues taken from 

 amphioxus, myxine, acanthias, and from teleosts; they were fixed by 

 the Golgi method and then stained after Heidenhain's iron-lack-hema- 

 toxylin. In all of these forms he finds the neuroglia made up of cells 

 and fibers, which are, however, in such relation to each other that all 

 the fibers may be regarded as processes of cells. 



As may be seen from the above brief summary of neuroglia litera- 

 ture giving accounts of observations made with the chrome-silver 

 method, all observers who have' used this method, even when such 

 method has been subjected to special modifications, have reached the 

 conclusion that the neuroglia is composed of cellular elements and 

 cell processes— neuroglia-cells and neuroglia-fibers, the latter being the 

 processes of the former. It is true that Andriezen found certain astro- 

 cytes in which the neuroglia fibers passed through the cell-body, and that 

 V. Kolliker regards himself justified in describing a cell-plate with cell- 

 processes, which may under certain conditions become separated from 

 the nucleated portion of the neuroglia cell, and that Reinke believes 

 that he has harmonized the conflicting views by his discovery of two 

 varieties of neuroglia fibers, the one being processes of neuroglia cells 

 and the other developed from the protoplasm and in part at least 

 emancipated from such protoplasm; yet a careful study of the account 

 and figures given by Andriezen and v. Kolliker does not reveal sufficient 

 evidence to indicate that these observers regard the neuroglia fibers as 

 other than processes of the neuroglia cells, and Eeinke's statement 

 will need further confirmation with methods other than a chrome-silver 

 precipitate before they can be accepted as established. At this date 

 it does not seem necessary to enter into a consideration of the chrome- 

 silver method as such, as its advantages and disadvantages have been 

 the subjects of frequent consideration and are now very generally 

 known; suffice it to say that we agree with Taylor when he states that 



