562 THE NERVOUS SYSTEM. 



In the case of slower death, after division of both the 

 pneumogastric nerves, the lungs are commonly found 

 gorged with blood, cedematous, or nearly solid, or with a 

 kind of low pneumonia, and with their bronchial tubes 

 full of frothy bloody fluid and mucus, changes to which, in 

 general, the death may be proximately ascribed. These 

 changes are due, perhaps in part, to the influence which 

 the pneumogastric nerves exercise on the movements of 

 the air-cells and bronchi ; yet, since they are not always 

 produced in one lung when its pneumogastric nerve is 

 divided, they cannot be ascribed wholly to the suspension 

 of organic nervous influence (J. Reid). Rather, they may 

 be ascribed to the hindrance to the passage of blood 

 through the lungs, in consequence of the diminished 

 supply of air and the excess of carbonic acid in the air- 

 cells and in the pulmonary capillaries (see p. 229) ; in 

 part, perhaps, to paralysis of the blood-vessels, leading 

 to congestion; and in part, also, as the experiments of 

 Traube especially show, they appear due to the passage 

 of food and of the various secretions of the mouth and 

 fauces through the glottis, which, being deprived of its 

 sensibility, is no longer stimulated or closed in conse- 

 quence of their contact. He says, that if the trachea be 

 divided and separated from the oesophagus, or if only the 

 oesophagus be tied, so that no food or secretion from above 

 can pass down the trachea, no degeneration of the tissue 

 of the lungs will follow the division of the pneumogastric 

 nerves. So that, on the whole, death after division of the 

 pneumogastric nerves may be ascribed, when it occurs 

 quickly in young animals, to suffocation through me- 

 chanical closure of the paralyzed glottis : and, when it 

 occurs more slowly, to the congestion and pneumonia pro- 

 duced by the diminished supply of air, by paralysis of the 

 blood- vessels, and by the passage of foreign fluids into the 

 bronchi ; and aggravated by the diminished frequency of 

 respiration, the insensibility to the diseased state of the 



