GANGLION CELLS 145 



they are studied. That is to say, they are flattened to some 

 extent in a direction at right angles to their longitudinal 

 extension (Fig. 4, c). The nucleus shows an elongated oval 

 or sausage -like symmetrical shape when seen from this 

 flattened side, and is always surrounded with a border 

 formed by a single layer of meshes of protoplasm. At the 

 ends of the nucleus the protoplasm is continued into the 

 narrower portion of the cells, where it assumes a more or 

 less longitudinally fibrillated structure. In the width of 

 that portion of the cell which is drawn out like a band 

 there do not, however, occur more than about three meshes. 

 In the aspect in which the cells usually show them- 

 selves, namely, at right angles to that already mentioned, 

 as seen when lying along the isolated nerve fibres, the 

 nucleus is asymmetrical (Plate VIII. Fig. 4, &) and makes 

 the cell bulge out strongly on one side. This bulging out, 

 so far as I have paid attention to the matter, which is 

 beside my main subject, is always situated in the depression 

 formed at one of Eanvier's nodes in the nerve fibre, and 

 quite fills it up. The thread-like portion of the cell 

 appears to be a single mesh thick in this aspect, and there- 

 fore shows the same relations as have already been described 

 in the walls of the capillaries. On the flat side of the 

 nucleus I could trace out the simple layer of protoplasm 

 distinctly. Whether a similar protoplasmic envelope occurs 

 also on the convex side was not to be made out with 

 certainty ; nevertheless I do not doubt the fact of its 

 occurrence. 



13. Ganglion Cells and Nerve Fibres 



Ganglion Cells 



I have isolated in various ways ganglion cells from the 

 spinal cord of the calf and from the ventral nerve cords of 

 Lurtibricus terrestris and Astacus flumatilis, and have always 

 convinced myself in the clearest manner that their structure 

 is a fibrous meshwork. Since there are already in exist- 

 ence a considerable number of sufficiently good figures that 



10 



