NAUSEA. 351 



sympathetic nerve; but the latter, it must be remembered, contains 

 fibres derived from the cerebro-spinal system. It has been shown that 

 the sense of hunger, as manifested by the desire of animals for food, 

 is not permanently destroyed, but merely diminished, after division of 

 the pneumogastric nerves (Reid and Bernard) ; but whether the per- 

 sistence of hunger is owing to the subsequent reunion of those nerves, 

 or to the action of the still uninjured sympathetic branches, is not 

 known. The sensation of satiety is said to persist in animals, as evi- 

 denced by their conduct, even after division of the pneumogastric 

 nerves : but the experiments on this point are not satisfactory. The 

 final cause of the sensation of hunger, not only in animals, but in 

 man, is to impel them to seek for the food absolutely necessary to sus- 

 tain life ; and indirectly, hunger may be said to stimulate men, in an 

 uncivilized state, to the chase, or to mutual conflict, and, in civilized 

 society, to the exercise of their intellect and bodies in industrial and 

 other occupations. 



The progress from fasting to starvation, is at first accompanied by 

 an exaggeration of the sensation of hunger to a ravenous craving 

 after food; but after a time, if unsatisfied, this sensation passes off, a 

 condition of indifference to food supervenes, and no further sensation 

 of appetite is experienced, extreme prostration and diminution of sen- 

 sibility setting in, and ending in delirium and death. 



Another sensation, chiefly referred to the stomach, is that of nausea, 

 which, however, is often accompanied by distressing sensations about 

 the pharynx and palate, and by general sensations of depression, sink- 

 ing at the precordia or pit of the stomach, arid a lowering of the heart's 

 action. It is said to be a muscular sensation (Weber), though formerly 

 it was regarded as a modified gustatory sensation. It may be pro- ' 

 duced in many ways, as, by irritation of the stomach, indigestion, 

 improper quality or quantity of the food or drink, or by emetic medi- 

 cines introduced either into the stomach, or the lower part of the 

 alimentary canal, or injected beneath the skin, so that they can be 

 absorbed into the blood, or even by the injection of such substances 

 directly into the bloodvessels. Nausea may also be induced through 

 the nervous system, as a reflex phenomenon, by tickling the fauces, 

 or by the inhalation of chloroform (through its action on the brain), 

 by odors or tastes, by the motion of vessels at sea, by severe pain, 

 by concussion or diseases of the brain, by conditions of the blood in 

 the early stages of fever, by the sympathetic effect of various diseases, 

 by general shock from severe injuries, especially from blows over the 

 great solar plexus, and even by mental causes. It is certain, there- 

 fore, that this sensation of nausea, or sickness, though referred to the 

 stomach, must depend, sometimes, at least, upon general conditions of 

 the system. The movement excited by the condition of nausea or 

 sickness, named vomiting, will be mentioned after the description of 

 the movements of the stomach, in the Section on Digestion. 



The internal sensations associated with the circulating system, are 

 fewer than those connected with the digestive organs, at least in a 

 state of health, in which not even the powerful and incessant action 

 of the heart is perceived by the mind. Were it otherwise, the amount 



