V 



117 



on a second dilatation. It must be assumed, therefore, that 

 centres exist in the cord which normally are controlled by 

 the bulbar centre, and that when severed from the latter will 

 become gradually independent. There are, in addition to the 

 vasomotor centres already mentioned, centres in the sympa- 

 thetic ganglia. Destruction of both bulbar and spinal centres 



FIG. 6 



Diagram illustrating the paths of vasocon- 

 strictor fibers along the cervical sympathetic 

 and (part of) the abdominal splanchnic (Foster) : 

 Aur., artery of ear; G.C.S., superior cervical 

 ganglion; Abd.SpL, upper roots of and part 

 of abdominal splanchnic nerve; V.M.C., vaso- 

 motor centre in medulla; C.Sy., cervical sym- 

 pathetic; G.C., lower cervical ganglion; Q.Th.* 

 to G.Th. 7 , the thoracic ganglia, first to seventh 

 both inclusive; D.I I and D.V, respectively the 

 second and fifth dorsal nerves; An.V., annulus 

 of Vieussens. The paths of the constrictor 

 fibers are shown by the arrows. The dotted 

 line in the spinal cord, Sp.C., is to indicate the 

 passage of constrictor impulses down the cord 

 from the vasomotor centre in the medulla. 



Sp.C. 



does not destroy arterial tone completely. For example, 

 the lower portion of the spinal cord of a dog was removed for 

 about 80 mm. The dilatation of the vessels of the hind limbs 

 which followed was succeeded in time by a constriction, leav- 

 ing the temperature of the limbs even cooler than normally. 

 Long oscillations in blood-pressure curves due to vaso- 



