Meyer, Data of Modem Neurology. 131 



stances which are emancipated from the cell bodies and which 

 no longer can be considered to be immediately connected with 

 the cell.' "I. Because with Weigert's new stain everything 

 nervous and even the protoplasm of the neuroglia cells, remains 

 unstained, the fibers of the neuroglia however are stained dark 

 blue (conclusion per exclusionem). 



2. Because the fibers contain a modified substance which 

 is no longer protoplasmic, but emancipated from the cell body. 



3. Because the fibers (and the cells belonging to them) 

 react under pathological conditions just as connective tissue, i. 

 e. , they proliferate when the specific nervous tissue perishes " 

 (pp. 115-117)- 



The clause in the third reason seems significant. It relates 

 to the fact that the cells too proliferate [and must proliferate in 

 order to produce fibrills]. Further the reason for the complete 

 emancipation of the fibrils is decidedly not absolutely convinc- 

 ing. The writer could never resist a certain comparison of the 

 results of Weigert's neuroglia stain with the results of his stain 

 for medullated fibers. Only those parts of the neurone retain 

 the haematoxylin which have enough myelin and kindred sub- 

 stances, namely, in a correct stain, only the medullated part of 

 the fiber. Yet we have reason to consider the myelin sheath a 

 part of the neurone notwithstanding its peculiarity of chemical 

 constitution. The neuroglia stain does not give a complete 

 stain of the neuroglia either, but only of the parts which con- 

 tain a definite substance. The difference lies in the greater 

 number of the fibrils, the lesser degree of organization, and the 

 difference in the distribution of this kind of specially stainable 

 substance which is by no means of a known constitution as in 

 the case of the myelin. Weigert advances " with the greatest 

 safety " the following theses (p. 105) : 



1. The neuroglia fibers which, so far, have been taken 

 for processes of the Deiters' cells, are not structures identical 

 with the protoplasm, but an absolutely different substance. 



2. The chemical difference does not appear slowly at a 

 more or less long distance from the cell-body in the "process- 



