VAGUS NERVE OF THE TURTLE aile 
fine, others coarse and the terminal bulbs vary greatly in size 
(fig.9). Arising from some of the axons are to be seen collaterals 
with terminal bulbs. Especially in the thoracoabdominal gan- 
glion many axons were split up near their origin into complicated 
aes 
Fig. 8 A small area of the thoracoabdominal ramus of the vagus at the level 
indicated by 4, figure 1, showing the myelin sheaths of the myelinated fibers as 
black rings and the neurilemma of the unmyelinated fibers as just visible rings 
which in the preparations are of the same tone of yellow as the connective tissue. 
Osmic acid. XX 955. 
Fig. 9 A cell from the cervical ganglion of the vagus showing protoplasmic 
processes with end bulbs. Pyridine silver. X 955. 
Kote nice Mi 
plexuses similar to those described by Dogiel (’08), Ranson (712) 
and others in mammalian cerebrospinal ganglia. But the 
sections were not thick enough to include more than a part of a 
plexiform axon in a single section and the details of these plexuses 
could not be readily worked out from serial sections. 
THEORETICAL CONSIDERATIONS 
1. In the mammal Chase and Ranson showed that the vagus 
nerve contains a very great number of unmyelinated fibers. 
Most of the large myelinated fibers leave the vagus through its 
cervical branches, while the majority of the unmyelinated 
fibers run downward in the main trunk to be given off in the 
thoracic and abdominal branches. The proportion of myelin- 
ated and unmyelinated fibers in the turtle’s vagus is approxi- 
mately the same as in that of the dog; and in both animals we 
find the myelinated fibers chiefly distributed in the cervical 
branches, while most of the unmyelinated fibers are distributed 
