THE NERVO-VASCULAR SUPPLY OP THE LUNGS. 475 



nerves that ultimately carry impulses to the adrenals are given 

 off.. 



We thus have considerable testimony, clinical and experi- 

 mental, in support of the view that the lungs contain vaso- 

 motor nerves. It behooves us now to delineate, if possible, the 

 extent to which each system general motor and vagal takes 

 part in the process. The experimental evidence, as we have 

 seen, only refers to the sympathetic fibers as vasomotors, and 

 this coincides with anatomical data. Sappey 36 studied the dis- 

 tribution of vagal nerves in the lungs of mammals, including 

 particularly those of man, the ox, and horse, and reached the 

 following conclusions: "1. They follow the subdivisions of the 

 air-tree to their terminal extremities; they do not leave these 

 subdivisions and follow them to the lobules. 2. All those that 

 leave the anterior pulmonary plexus and the much greater 

 number given off by the posterior pulmonary plexus preserve 

 their plexiform arrangement throughout their entire distribu- 

 tion; their meshes are elongated only in the line of their axis, 

 each thus constituting an elongated ellipse. 3. Their ramifica- 

 tions, essentially destined for the muscular coat of the bronchi 

 and respiratory mucous membrane, have no connection with 

 the blood-vessels." Berdal, on the other hand, confirms this, 

 and indicates the role of the sympathetic terminals in the fol- 

 lowing lines: "The branches of the pneumogastric are destined 

 for the bronchi; the branches of the great sympathetic are lost 

 in the walls of the arteries." 



This represents the actual anatomical conditions present, 

 in the light of available evidence, and there is no ground, even 

 from the standpoint of our conceptions, to modify them. It 

 is only when we inquire into the manner in which the two 

 systems of nerves affect function that present teachings and 

 our own views differ. Indeed, we have seen that section of 

 the vagi in the neck caused loss of sensation in the respiratory 

 mucous membrane, paralyzed the bronchial muscles, and gave 

 rise to effusion of mucus into the bronchi and engorgement of 

 the lungs. How can all these phenomena be accounted for 

 without granting sensory, motor, and vasomotor functions to 



86 Sappey: Loc. cit., p. 391. 



