366 DISEASES ClassIV. i. i. 



affected by their fympathy with thofe of the (kin, as appears from 

 rhe defect of fecretion in ulcers during the cold fits of agues. 



The motions of this extenfive fyftem of capillaries, thus aflb- 

 ciated by direct fympathy, are alfo affociated with thofe of the 

 heart and arteries, fometimes by reverfe and fometimes by di- 

 rect fympathy •, and thus constitute fimple fever. The cold 

 paroxyfm of which conlifts in their torpor, and the hot one in 

 their orgafm, or increafed activity. 



I. Of the AEllen of Vomiting. 



The manner, in which the ftomach and the diaphragm and 

 abdominal mulcles acquire their affociate action in vomiting, 

 requires fome attention. It is not probable, that this action of 

 vomiting occurs before nativity ; as the uniform application of 

 the nutritive liquor amnii to the mouth of the fcetus, and the 

 uniform expenditure of its nourifhment, would not feem to give 

 occafion to too great temporary repletion of the ftomach \ and 

 would preclude the deglutition of any improper material. After 

 nativity the ftomach of the child may be occasionally too much 

 diftended with milk ; as previous hunger may induce it to over- 

 gorge itfelf ; and by repeated efforts the act of vomiting is learn- 

 ed, as a means of getting free from a difagreeable fenfation. 

 Thus when any difguftful material, as a bitter drug, is taken 

 into the mouth ; certain retrograde motions of the tongue and 

 lips are produced, for the purpofe of putting the difagreeable 

 material out of the mouth again. 



When the ftomach is difagreeably ftimulated by the diftention 

 or acrimony of the aliment, a fimilar effort to regurgitate it muft 

 occur ; and by repeated trials the action of the diaphragm and 

 abdominal mufcles by fqueezing the ftomach affifts its retro- 

 grade exertion to difgorge its contents. In the fame manner 

 when a piece of gravel is pufhed into the urethra, or a piece of 

 indurated bile into the neck of the gall-bladder, after they have 

 been in vain prelfed forward by the ufual motions of thofe 

 ducts, they return into the bladders of gall and urine by the re- 

 trograde motions of them. 



That this is one mode, in which vomiting is induced, appears 

 from the inftantaneous rejection from the ftomach occafioned 

 by fome naufeous drug, or from fome naufeous idea ; and laft- 

 ly, from the voluntary power, which fome people have been faid 

 to have acquired, of emptying their ftomachs, much in the fame 

 manner as ruminating animals bring up the grafs from their 

 firft ftomach. 



There are neverthelefs many modes by which thefe inverted 



motions 



