302 S. WALTER RANSON 
in osmie acid but some was prepared by the pyridine silver 
technique. Except for the long stretch between the esophageal 
branch and the thoracoabdominal ganglion of the vagus the 
material was cut and mounted in serial sections. 
THE RELATION OF THE ACCESSORY NERVE TO THE VAGUS 
The vagus and accessory nerves are even more intimately 
associated with each other in reptiles than in mammals. In 
the turtle the accessory nerve has a separate existence only in 
its roots. After fusion with the vagus its fibers intermingle 
with those of that nerve. In the mammal the spinal part of the 
accessory maintains its identity as a separate fascicle throughout 
the common vagoaccessory trunk; but the bulbar part of the 
accessory fuses with, and becomes lost in the vagus nerve. In 
the turtle the spinal part of the accessory is very small; and its 
fibers, as well as those of the bulbar portion, intermingle with 
those of the vagus. Since in mammals we speak of the common 
trunk formed by the bulbar portion of the accessory and the 
rootlets of the vagus as the vagus nerve, we shall do least vio- 
lence to the accepted terminology if we speak of the common 
trunk formed by the union of the roots of the vagus and acces- 
sory nerves of the turtle as the vagus nerve. It should be 
remembered, however, that this common trunk contains a few 
fibers not properly belonging to the vagus but derived from the 
spinal root of the accessory and given off as a minute branch 
to some of the neck muscles. It is generally admitted that the 
bulbar part of the accessory is properly to be regarded as a part 
of the vagus (Chase and Ranson ’14). 
GROSS ANATOMY OF THE VAGUS NERVE 
The accessory nerve arises by four or five small rootlets from 
the posterior part of the lateral surface of the medulla in line 
with the rootlets of the vagus and by a spinal root. In one 
specimen studied in serial sections the spinal root was seen to 
arise as a single fascicle from the lower part of the second cervical 
segment of the spinal cord in line with the dorsal roots. In this 
