70 



DR. 0. F. SONNTAG ON THE VAGUS AND 



of either vagus ; and all the bratiches arose within the thorax 

 from : — 



a. The vagus nerves (constant). 



h. The left recurrent nerve (constant). 



c. The right recurrent nerve (not universal). 



In all forms the vagus cardiac branches contain some sympa- 

 thetic filaments, but in a few species they contain the entire 



Text-figure 5. 



L.V. 



The thoracic parts of the vagus nerves in Canis tlious. D.C.P. and S.C.P : deep 

 and superficial cardiac plexuses ; R.I : first rib ; s.v.h : sympathetic nerves 

 on subclavian arteries. Other letters as in text-fig. 4. 



sympathetic supply to the heart. The cardiac plexuses anastomose 

 with the anterior pulmonaiy plexuses, and with the nerves rovmd 

 the branches of the aortic arch. In some cases (text-figs. 4, 5, 6) 

 the vagus gives off well-marked nerves, whose bifurcating 

 terminal twigs run to both cardiac and anterior pulmonary nerves. 

 The actual components of the })lexuses are described on p. 76. 



