172 



PEA BODY. 



[VOL. I. 



seen under the highest powers of the microscope to be made 

 up of minute fibrillae. For a distance along their course these 

 fibrillae are separated more or less from one another, but at 

 certain points they are gathered tightly together (Fig. 7, ?>.). 

 When branches are given off, the individual fibrillae may be 

 traced continuously from the larger axis cylinders out along 

 the smaller branches (Fig. 7, n.ax.cyl.}. On these finer 

 branches is seen the same appearance of collecting and loosen- 

 ing out of fibrillae as has been described above. Such a fact 



FIG. 7. Method of branching of axis cylinders of nerves: d.c., deeper layer of cells ; n.ax.cyl., axis 

 cylinder of nerve ; ?'., points along course of axis cylinders where the nerve fibrillae are gathered 

 closely together, x 1*3 oil immers. 2 in. occular. 



suggests that the finest individual nerve fibril may be con- 

 tinuous from its peripheral termination back through the 

 bundle of fibers in which it has come, to its ganglion cell near 

 or in the brain. 



Along the course of the finest fibrillae little thickenings are 

 seen just at the base of the cells of the deeper layer (Figs. 8, 

 9, 11. k.}. Thus far I have never seen any branches running up 

 between the cells. If such branches were present I believe 

 they would be stained as the others are by the methylene blue. 

 The distribution of the nerves as described above has been 

 seen in many series of sections. 



In thick sections obtained by freezing and fixing the blue 

 with ammonium picrate the cells are stained yellow, the fibers 

 assuming the purple color characteristic of this treatment. If 

 one examines with very high powers the outer surface of the 



