PXEUMOGASTRIC XERVES. 215 



for example, to slightly moisten the slip of glass or oiled silk 

 which serves to isolate the two nerves, in order that the cur- 

 rent should act immediately upon the superior filaments of 

 the spinal accessory, from which we have marked contrac- 

 tions in the organs just mentioned." 1 



These experiments seem entirely conclusive. In treat- 

 ing of the reflex phenomena of deglutition and their rela- 

 tions to the superior branches of the pneumogastric, the 

 pharyngeal, and the superior laryngeal, it will be seen that 

 irritation, either of these nerves or of the mucous membranes 

 to which they are distributed, will produce contractions in 

 the muscles. All who are practically familiar with the ap- 

 plication of electricity to the nerves know how difficult it is 

 to insulate the nervous trunks so as to avoid the influence 

 of "derived" currents. In carefully studying the experi- 

 ments of Longet, it seems that all the physiological condi- 

 tions were fulfilled ; and that when the nerve is divided at the 

 root and the stimulation is applied to the peripheral end, so 

 as to cut oif all reflex action from the nervous centres, and 

 when sufficient care is exercised to prevent the propagation 

 of the current to the motor connections of the pneumogas- 

 tric, the nerve, from its origin at the medulla oblongata to 

 the ganglion of the root, contains no motor filaments, and 

 is therefore exclusively sensory. 



Among the more recent experiments which have led to 

 the view that the roots of the pneumogastrics contain motor 

 filaments, are those of Chauveau, made in 1862, and of Yan 

 Kempeu, published in 1863. In the experiments of Chau- 

 veau, the excitation was applied to the roots of the nerves 

 in animals just killed, with the effect of producing energetic 

 contractions of the oesophagus and stomach. The roots, 

 however, were not divided. 2 It is stated in this article that 

 all reflex action ceases in adult mammals with the move- 



1 LOXGET, Trait'e de physiologic, Paris, 1869, tome iii., p. 508. 



2 CHAUVEAU, Du nerf pneumogastrique, etc. Journal de la physiologie, Paris, 

 1862, tome v., p. 198. 



