46 Studies on the Neuroglia 



As is now very generally known, the chrome-silver method shows the 

 neurogliar tissue to consist of cellular elements possessing a varying 

 number of tibrillar processes. These structural elements have been 

 designated by v. Lenhossek by the very appropriate name of astrocytes, 

 and are subdivided into (a) astrocytes with long processes, found in the 

 white and grey matter, and (b) astrocytes with short processes, found 

 only in the grey matter. In these few words we have endeavored to 

 reflect, as well as possible in so short a space, the views of the majority 

 of the early observers who have used the chrome-silver method in the 

 study of neuroglia. V. Kolliker, while agreeing in the main with the 

 above statement of the structure of the neuroglia, describes the fully- 

 developed astrocyte, which he terms a Golgi-cell, as consisting of two 

 portions — a cell-body containing the nucleus which is intimately asso- 

 ciated with a cell-plate, from which the cell processes arise. He sug- 

 gests the hypothesis that " a Golgi-cell with a portion of its protoplasm 

 develops a cell-plate from which the cell processes arise; this plate 

 originally and as long as the processes possess the power of growth is 

 intimately connected with the nucleated portion of the Golgi-cell; in 

 many instances, however, the cell-plate attains a different consistency 

 and perhaps also a different constitution and, under certain conditions, 

 may sever its connection with the nucleated portion of the Golgi-cell." 

 Andriezen, who has used the chrome-silver method in studying the 

 neurogliar tissue of the brain cortex, recognizes two varieties of neu- 

 roglia cells. One of these, which he has designated as the neuroglia 

 fiber cells, corresponds in the main with the astrocytes with long pro- 

 cesses described by other writers. It should, however, be stated that 

 this observer was able to make out in certain of his preparations that 

 not all neuroglia fibers are processes of cells, but that many of them 

 "pass right through the cell body." The other variety of neuroglia cell 

 is 'described by him under the name of protoplasmic glia cell, and has 

 stout, coarse and very shaggy processes, which vary very greatly in size. 

 These latter cells are said to be of mesoblastic origin. Eeinke, who, in 

 his study of neuroglia tissue, has made use of a modified chrome-silver 

 method (after obtaining a chrome-silver precipitate, he dehydrated and 

 then imbedded his tissue in paraffin, fixed the sections with albumin 

 fixative and then stained them with Heidenhain's hematoxylin and 

 counterstained them in eosin), has obtained results which deserve espe- 

 cial mention. His conclusions are " that the neurogliar tissue of the 

 white substance of the human cord consists of (1) cells and (2) fibrils. 

 The cells possess numerous processes, some of which are branched and 

 which run in part transversely and in part obliquely; the majority of 



