CHAP. XX.] THE SPINAL ACCESSORY NERVE. 125 



Section of them may cause in the first instance vomiting and loath- 

 ing of food, and it may retard the digestive process, but it does not 

 put an end to it. For not only do animals, with the vagi cut, 

 eat food from day to day, but, if killed at a sufficient period after 

 digestion, their lacteals are found filled with chyle, affording un- 

 equivocal evidence of the persistence of the digestive process. 



Nor does the section of these nerves destroy the secretion of the 

 gastric fluid, for the matter vomited affords evidence of its having 

 been mingled with acid, and the fact of the formation of chyle proves 

 that stomach digestion must have taken place. Miiller and DickhofF, 

 in their experiments upon section of the vagi in geese, found the fluid 

 secreted by the stomach distinctly acid. In Dr. Reid's experiments, 

 the ordinary mucous secretion of the stomach was found in its usual 

 quantity, and when arsenic was administered to the animals, the 

 mucous secretion was quite as abundant as in others in which the 

 vagi nerves were not cut. 



The few pathological facts which can be collected of diseased 

 states of the vagi nerves are confirmatory of the conclusions deduci- 

 ble from anatomy and experiment. Several instances are recorded 

 of loss of voice and dyspnoea, symptoms resembling those of chronic 

 laryngitis, caused by the compression of the recurrent by an aneu- 

 rismal or other tumor. The violent convulsive cough, which accom- 

 panies enlarged bronchial glands, is probably due to the irritation 

 of the pulmonary branches of the vagi nerves. Hooping-cough is 

 probably an affection of the vagi nerves by a peculiar poison. Dr. 

 Ley attributed the phenomena of laryngismus stridulus to the irri- 

 tation of enlarged cervical glands, affecting the recurrent nerves, 

 and there seems no doubt, that, although the symptoms of this 

 disease occur more frequently as part of a peculiar exhausted state 

 of system, they may be, and are, produced sometimes by the local 

 irritation of such glands. 



The diseases in which this nerve is involved are chiefly those 

 which affect its gastric and pulmonary branches. The sympathy 

 wliich all practitioners admit to exist between the digestive and 

 respiratory organs is explained by the anatomical relations of this 

 nerve. Asthma is essentially an irritation of the centre of respira- 

 tion and of this nerve; this disease almost invariably begins by 

 some deranged state of digestion, or by the introduction of some 

 poisonous material from without ; some very subtle material sus- 

 pended in the air, and brought by inhalation into contact with the 

 respiratory surface, for example, the minute particles which pass off 

 from powdered ipecacuanha, or from hay. Asthma and intermittent 



