NERVE CELLS OF THE CRAYFISH 49 
The fibrillae of the intracellular axone in its more compact 
portions are more or less sinuous in their general course, which 
is spiral. The spiral arrangement may be observed in longi- 
tudinal sections and also in cross-sections of the tract. In 
some cross-sections observed, 4, in thickness, this is shown 
most beautifully by focusing on different planes. As the objec- 
tive is raised or lowered bringing different planes into view, 
there is a very striking appearance of a corkscrew movement on 
the part of the sections of the fibrillae. 
In the gold-toned Cajal preparations and also in the Kopsch 
preparations diverging fibrillae may be traced out from the 
compact intracellular axone into the cytoplasm for a short 
distance. Cross-sections of the tract, and also longitudinal 
sections, may show such fibrillae coming from the cytoplasm 
throughout the entire length of the intracellular axone. The 
greater abundance of the diffusely distributed fibrillae, however 
is to be found in the basal part of the cell and in the portion of 
the cell on the side opposite the compact part of the axone. 
One cell stained intravitam with 0.01 per cent thionin showed 
a fibrillar feltwork throughout the entire cytoplasmic mass, 
having the appearance of radiating from a point near the nucleus. 
The apparent reticulation was denser, of more numerous and 
finer meshes, in the portion of the cell distal to the axone exit. 
Some other cells showed a more equable distribution of the felt- 
work. Many of the cells stained in this way are very small 
and the fibrillae extremely delicate. The latest attempts at 
intravitam staining with 0.02 per cent thionin in normal salt 
solution indicate the presence of delicate fibrillae in the same 
position in the cytoplasm and with the same relation to the 
nucleus as is so distinctly shown in the fixed and stained speci- 
mens. ‘Two and one half cubic centimeters of the thionin solu- 
tion were injected into the pericardial sinus, with some loss, 
this being followed by two injections of a like quantity, 
thirty minutes intervening between two consecutive injections. 
Twenty minutes after the third injection the crayfish was decapi- 
tated and the cord removed into the thionin solution. Some 
cells were soon found, within twenty minutes, showing faint 
