24 CHARLES F. W. MC CLUEE, 



cellulaire^). Dans ce trajet, le cylindre-axe se distingue nettement 

 du protoplasma par la puissance avec laquelle il concentre la matière 

 colorante." 



Again on p. 480, he says: "Le faisceau est formé des mômes 

 fibrilles accolées ensemble que dans le cylindre-axe extracellulaire". 

 In regard to the structure of the cell body, he describes it as con- 

 sisting of two elements — namely, of fibrils, and of an interfibrillar 

 substance. Each of these elements stain differently when treated by 

 the method of Viallanes; the fibrils stain blue and the interfibrillar 

 substance red. If I understand him correctly, he considers the fibrils 

 to be distributed throughout the cell body, but most abundant in the 

 cortical layer; while the interfibrillar substance is most abundant in 

 the centre of the cell around the nucleus. His figures represent this 

 interfibrillar substance as granular in character; but he makes no 

 reference to the row-like arrangement of these granules in the cell 

 body, nor to their correspondence to the chromophilous substance 

 found in the nerve cells of Vertebrates. 



Unfortunately, I have been unable to see the publication by 

 DE Nabias (24), so that any criticism of his work is impossible. I 

 insert, however, the reference, so that the bibliography on this sub- 

 ject may be as complete as possible. 



A recent publication by Pflücke (30) deals chiefly with the 

 structure of the nerve cells of Astacus. He studied these cells in 

 the fresh state, as well as by sections. For fixing agents, sublimate 

 and Flemming's solution gave the best result; while for staining, 

 Nissl's methylen blue method, safranin, fuchsin and iron -haematoxy lin 

 after Heidenhain were used. 



Corresponding to the discoveries of Nissl and others on the 

 cells of Vertebrates, PflIjcke similarly finds in the nerve cells 

 of Astacus, two substances which possess unlike affinities for 

 methylen blue. The manner, in which these cells are stained, is best 

 expressed in his own words (p. 514) : " — nämlich in eine stark färbbare, 

 structurgebende Substanz und in eine anscheinend homogene, kaum 

 oder überhaupt nicht gefärbte Zwischenmasse." The first of these 

 substances is represented by a Jarge number of deeply stained granu- 

 lar appearing structures which lie close to each other, and which 

 vary in size and form; some of them being spindle-shaped, others 



1) I have also observed these structures in the nerve cells of 

 Camharus, Homarus and Astacus (see 22), but reserve a description 

 of the same for a future paper. 



