39* RETROGRADE ABSORBENTS. SECT. XXIX. rr, 



The experiment therefore above related upon the 

 la&eals of a dead pig, which were included in a 

 ftritSt ligature, proves nothing ; as it is not the quan- 

 tity, but the kind of ftimulus, which excites the 

 lymphatic veflels into retrograde motion. 



XI. The Caufes which induce the retrograde Motions of 

 animal Vejjels; and the Medicines by which the natu- 

 ral Motions are rejlored. 



1. SUCH is the conftru&ion of animal bodies, 

 that all their parts, which are fubjecled to lefs ft i- 

 muH than nature deligned, perform their functions 

 with lefs accuracy : thus, when too watery or too 

 acefcent food is taken into the ftomacb, indigeftion, 

 and flatulency, and heart-burn fucceed. 



2. Another law of iiritation, connate with our 

 exiftence, is, that all thofe parts of the body, which 

 have previoufly been expofed to too great a quantity 

 of fuch ftimuli, as ftrongly affe<St them, become for 

 fome time afterwards difobedient to the natural 

 quantity of their adapted ftimuti. Thus the eye is 

 incapable of feeing objecls in an obfcure room, 

 though the iris is quite dilated, after having been 

 Expofed to the meridian fun. 



3. There is a third law of iiritation, that all the 

 parts of our bodies, which have been lately fabject- 

 cd to lefs ftimulus, than they have been accuftomed 

 to* when they are expofed to their ufual quantity of 

 ftimulus, are excited into more energetic motions : 

 thus when we come from a dufky cavern into the 

 glare of daylight, our eyes are dazzled ; and after 

 emerging from the cold bath, the fldn becomes warm 

 and red - 



4. There is a fourth law of irritation, that all 

 the parts of our bodies, which are fubje&ed to ftill 

 Wronger ftimuli for a length of time, become tor* 



and refufe co obey even thefe ftronger ftimuli ; 



and 



