SECT. XXIX. i. RETROGRADE ABSORBENTS. 355 



more frequently than in the dead, they prevent the 

 chyle from returning. The principal of thefe valves 

 is that, which prelides over the infertion of the 

 thoracic duel, into the fubclavian vein ; many have 

 believed this alfo to perform the office of a valve, 

 both to admit the chyle into the vein, and to pre- 

 clude the blood from entering the duel; but in my 

 opinion it is fcarcely fuffiqitnt for this purpofe." 

 Haller, Elem. Phyf. t. vii. p. 226- 



2. The mouths of the lymphatics feem to admit 

 water to pals through them after death, the invert- 

 ed way, eafier than the natural one ; fmce an in- 

 verted bladder readily lets out the water with which 

 it is filled; whence it may be inferred, that there is 

 no obftacle at the mouths of thefe veflels to prevent 

 the regurgitation of their contained fluids. 



I was induced to repeat this experiment, and 

 having accurately tied the ureters and neck of a 

 frefii ox's bladder, I made an opening at the fundus 

 of it ; and then, having turned it infide outwards, 

 filled it half full with water, and was furprifed to 

 fee it empty itfelf fo haftily. I thought the experi- 

 ment more appofite to my purpofe by fufpending the 

 bladder with its neck downwards, as the lymphatics 

 are chiefly fpread upon this part of it, as fhewn by 

 Dr. Watibn, Philof. Tranf. v. 59. p. 392. 



3. In fome difeafes, as in the diabetes and fcro- 

 phula, it is probable the valves themfelves are dif- 

 eaied, and are thence incapable of preventing the 

 return of the fluids they mould fupport. Thus the 

 valves of the aorta itfelf have frequently been 

 found fchirrous, according to the difle&ions of 

 Monf. Lieutaud, and have given rife to an inter- 

 rupted pulfe, and laborious palpitations, by fuffer- 

 ing a return of part of the blood into the heart. 

 Nor are any parts of the body fo liable to fchirro- 

 fity as the lymphatic glands and veflels, infomuch 



that 



