220 OF T& STOMACH SECT. XXV. j. 



7. At the fame time that thefe motions of the ftomach and 

 throat are ftimulated into inverfion, fome of the other irritative 

 motions that had acquired more immediate connexions with the 

 ftomach, as thofe of the gaftric glands, are excited into ftronger 

 action by this affociation ; and fome other of thefe motions, 

 which are more eafily excited, as thofe of the gaftric lymphatics, 

 are inverted by their aflbciation with the retrograde motions of 

 the ftomach, and regurgitate their contents, and thus a greater 

 quantity of mucus, and of lymph, or chyle, is poured into the 

 ftomach, and thrown up along with its contents. 



8. Thefe inverfions of the motion of the ftomach in vomiting 

 are performed by intervals, for the fame reafon that many other 

 motions are reciprocally exerted and relaxed ; for during the 

 time of exertion the ftimulus, or fenfation, which caufed this ex- 

 ertion is not perceived ; but begins to be perceived again, as 

 foon as the exertion ceafes, and is fome time in again producing 

 its effect. As explained in Sel. XXXIV. on Volition, where 

 it is {hewn, that the contractions of the fibres, and the fenfation 

 of pain, which occafioned that exertion, cannot exift at the fame 

 time. The exertion ceafes from another caufe aifo, which is the 

 exhauftion of the fenforial power of the part and thefe two cauf- 

 es frequently operate together* 



9. At the times of thefe inverted efforts of the ftomach not on- 

 ly the lymphatics, which open their mouths into the ftomach, 

 but thofe of the fkin alfo, are for a time inverted : for Iweats are 

 fometimes pufhed out during the efforts of vomiting without an 

 increafe of heat. 



TO. But if by a greater ftimulus the motions of the ftomach 

 are inverted ftill more violently or more permanently, the duod- 

 enum has its periftaltic motions inverted at the lame time by 

 their aflbciation with thofe of the ftomach ; and the bile and pan- 

 creatic juice, which it contains, are by the inverted motions 

 brought up into the ftomach, and difcharged along with its eon*, 

 tents ; while a great quantity of bile and pancreatic juice is pour- 

 ed into this inteftine ; as the glands that fecrete them, are by 

 their aflbciation with the motions of the inteftine excited into 

 ftronger ad ion than ufual. 



ii. The other inteftines are by aflbciation excited into more; 

 powerful action, while the lymphatics, that open their mouths 

 into them fuffer an inverfion of their motions correfponding with 

 the lymphatics of the ftomach and duodenum ; which with a 

 part of the abundant fecretion of bile is carried downwards, and 

 contributes both to ftimulate the bowels, and to increafe the quan- 

 tity of the evacuations. This inverfion of the motion of the lym- 

 phatic* appears from the quantity of chyle, which comes away 



