PULMONARY NEKVES. 235 



the pneumogastrics in connection with respiration, has been 

 ascertained by the numerous experiments on record of sec- 

 tion of one or both of these nerves in the cervical region. 

 It has been found by all experimenters, that animals survived, 

 and presented no very distinct abnormal phenomena, after 

 section of one nerve. Longet states that animals operated 

 upon in this way present hoarseness of the voice and a slight 

 increase in the number of respiratory acts. Some observers 

 have found the corresponding lung partly emphysematous 

 and partly engorged with blood, and others have not noted 

 any change in the pulmonary structure. 1 



When both nerves are divided in full-grown dogs, an ex- 

 periment which we have often repeated, the effect upon the 

 respiratory movements is very marked. For a few seconds, 

 the number of respiratory acts may be increased ; but as 

 soon as the animal becomes tranquil, the number is very 

 much diminished, and the movements change their charac- 

 ter. The inspiratory acts become unusually profound, and 

 are attended with excessive dilatation of the thorax. The 

 animal is generally quiet and indisposed to move. We have 

 seen, under these conditions, the number of respirations fall 

 from sixteen or eighteen to four per minute. 



In most animals that die from section of both pneumo- 

 gastrics, the lungs are found engorged with blood, and, as it 

 were, carnified, so that they sink in water. This curious 

 fact was noted by Legallois ; 2 and although its physiological 

 significance is not apparent, it has been the subject of much 

 speculation and experimental research. Many attempts have 

 been made to account for this peculiar condition. Traube 

 supposed that it was due to the penetration of secretions 

 into the respiratory passages ; 3 but this was disproved by 



1 LONGET, Anatomie et physiologic du systeme nerveux, Paris, 1842, tome ii., 

 p. 349, et seq. 



MAGEXDIE, Phenomenes physiques de la vie, Paris, 1842, tome i., p. 204. 



2 LEGALLOIS, (Euvres, Paris, 1824, tome i., p. 194. 



3 TRACBE, Die Ursachen und die Bes$haffenheit derjenigen Veranderungen, 



