174 JOURNAL OF COMPARATIVE NEUROLOGY. 
PLATE V. 
All the figures are from toluidin blue preparations of Azrudo. Figures 2 
and 3 are from material fixed in ether. 
Fig. r. An oblique section through a large ganglion cell and a portion of 
the neuropil, showing the connection between the fibrillae in the cell process. 
The greater part of the cell is cut away. a, 4,two fibrillae from the longi- 
tudinal commissures; ¢c,a short fibril connecting @ and 4; d, the bounding 
membrane between neuropil and ganglion cells. 
Fig 2. A-small ganglion cell with its process, portions of the peripheral 
fiber (4), and of two collaterals. Part of the peripheral fibrillar network is seen 
in the cell; in that region of the element, from which the collaterals branch 
off, a large fibril (a) may be traced from one of the collaterals into 4, the 
peripheral fiber, where it is designated by a’. 
Fig. 3. A ganglion cell of medium size from the same section as Figure 
2. Only the neurofibrillae and the nucleus were visible in the preparation. 4, 
the single large fibril in the cell process ; a, one of its branches which unites 
with the network about the nucleus. 
Fig. g. A section through the peripheral portion of a giant ganglion cell, 
showing the close-meshed fibrillar network characteristic of the larger cells of 
Hirudo. 
Fig. 5. Ashort portion of a cell process showing the connection between 
its neurofibrillae ; a, a’, a’’, three fibrillae which in passing from the cell into 
the neuropil, unite at 6; atc asingle mesh is formed, from which numerous 
small fibrillae continue their course in the process. The perifibrillar substance 
is not stained. 
Fig. 6. One of the simpler cases of fibrillar networks found in the 
neuropil of Azrudo. Only two meshes are formed, which are in connection 
with three fibrillae. 
Fig. 7. An example of the fibrillar networks in the processes of large 
nerve elements. a, proximal end of the cell process; 4, bounding membrane 
of the neuropil; ¢, the network by which all of the fibrillae are connected 
together ; d, a large neurofibril which unites at e with a smaller network. 
Fig. 8. A fibrillar network of four meshes found near the center of the 
neuropil. a-/, fibrillae uniting with the network. 
PLATE VI. 
Figure 14 is a toluidin blue preparation from Airudo. All the other fig- 
ures are methylen blue preparations from Ast¢acus material. 
Fig. 9. Anetwork of neurofibrillae from the third abdominal ganglion 
of Astacus. At the point a the network is apparently connected with the longi- 
tudinal nerve fiber 4; c, beads of perifibrillar substance, characteristic of 
methylen blue preparations. 
Fig. ro. <A large motor nerve element from the second abdominal 
ganglion of Astacus. a, the enlarged portion of the fiber from which the 
collaterals branch off; 4, the much smaller cell process; ¢, the peripheral 
nerve fiber, traced, in the preparation, to one of the lateral nerves; d, two 
collaterals. XX 160. 
