630 DIGESTION. 



and he details the singular case of a female, who, whilst labouring under 

 an affection, for which emetics seemed to be required, resisted the action 

 of the most powerful substances of that nature. After her death, M. 

 Lieutaud, feeling desirous to detect the cause of this resistance, had 

 the body opened in his presence: the stomach was found enormously 

 distended, but its structure unaffected. He, consequently, inferred, 

 that the stomach had become paralysed from over-distension, and that 

 the effect produced was similar to that, so often met with in the bladder, 

 when it has been long and largely distended. This case seemed to prove 

 to him, that the stomach is most concerned in the act of vomiting, as 

 . the abdominal muscles and diaphragm appeared healthy, and no obstacle 

 existed to their contraction. It is singular, however, that emetics should 

 not have excited the contraction of the diaphragm and abdominal mus- 

 cles; especially as there is reason for believing, that many of them at 

 least, under ordinary circumstances, are taken into the bloodvessels, 

 and affect the brain first, and through its agency the muscles con- 

 cerned in the act of vomiting. The case seems to have been one of 

 unusual resistance to the ordinary effects of nauseating substances, and 

 cannot be looked upon as either favourable or unfavourable to the views 

 of Bayle. We find, that vomiting does not follow the exhibition of the 

 largest doses of the most powerful emetics, if the energy of the nervous 

 system be suspended by the inordinate use of narcotics, or by violent 

 injuries of the head. M. Lieutaud farther remarks, that according to 

 Bayle's theory vomiting occurs at the time of inspiration; but this 

 cannot be, as the lower part of the oesophagus is then contracted, and 

 if the vomited matters could reach the pharynx, they would pass into 

 the larynx. 



Dr. Marshall Hall 1 has attempted, and successfully, to show, that the 

 larynx is closed during vomiting; and has concluded, that the act is a 

 modification of expiration, or that the muscles of expiration, by a sud- 

 den and violent contraction, press upon the contents of the stomach, and 

 project them through the oesophagus. Perhaps as Dr. Hall has re- 

 marked no act affords a better illustration of the action of the excito- 

 motory or reflex system of nerves than this. If the upper part of the 

 throat be tickled with a feather, vomiting results ; but if the feather be 

 passed too far down, deglutition is induced and not vomiting. The ex- 

 citor nerves, in the former case, are the glosso-pharyngeal, and perhaps 

 the fifth pair. When vomiting is caused by an emetic, the pneumogas- 

 tric is the excitor. When the impression is first made on the brain, 

 the stimulus must be conveyed by the medulla oblongata and medulla 

 spinalis to the muscles concerned. 



Haller 2 maintained the ancient doctrine, that the stomach, alone, is 

 competent to the operation. His views were chiefly founded on his 

 theory of irritability, which compelled him to admit contraction wherever 

 there are muscular fibres; and on certain experiments of Wepfer, 3 who 

 asserted, that when he produced vomiting by mineral substances, he 

 observed the stomach contract. The Academie des Sciences of Paris, 



1 Journal of Science and Arts, xv. 388. 



2 LOG. citat. 3 Cicutse Aquaticse Historia, &c., Basil, 1679. 



