32 M. R. CHASE AND S. W. RANSON 



TECHNIQUE 



In dissecting out the \'agus nerve in the dog, the bone was re- 

 mo\'ed from around the jugular foramen; and the jugular gan- 

 ghon, and the vagus and accessory roots were exposed. The com- 

 mon trunk of the vagus and accessory nerves was removed along 

 with then- roots and a piece of the medulla oblongata, to which 

 these roots were left attached. The so-called external branch of 

 the accessory was cut away. The superior cervical ganglion of 

 the sympathetic was separated from the carotid plexus and left 

 attached to the vagus by the cervical sympathetic trunk, which 

 in the dog runs in a common connective tissue sheath with the 

 vagus. The inferior cervical ganglion of the sympathetic was left 

 attached to the lower end of this common trunk. The pharyn- 

 geal, superior laryngeal and recurrent nerves were dissected out 

 and left attached to the vagus. The vagus trunk in the thorax 

 was removed along with its pulmonary rami and the esophageal 

 plexus. In some dogs the entire vagus with its branches and its 

 connections with the sympathetic was dissected out and pre- 

 served. From other dogs only desired portions of the nerve were 

 removed. Most of the preparations were taken from the vagus 

 of the right side. 



Although most of the work was done on the dog, the vagus was 

 also studied in man and in the rabbit, cat and rat. The intimate 

 association of the vagus and sympathetic in the dog, which at 

 first sight might appear to complicate the study, is in fact an 

 aid. The sympathetic is always at hand for comparison with 

 the vagus. The two trunks, though contained within one con- 

 nective tissue sheath in the neck, retain their individuality as 

 completely as in those animals in which they are most widely 

 separated. 



Most of the material was cut into serial sections. In this way 

 all branches of the vagus and connections with the sympathetic 

 could be followed accurately. This is especially important in 

 the study of the roots of the vagus, and in the study of the rela- 

 tions of the vagus and sympathetic. Some of the material was 

 fixed in ammoniated alcohol and stained by the pyridine-silver 



