- 4 o RETROGRADE Sect. XXIX. i. 6, 



very frequent between the inteflinal and urinary lymphatics, as 

 r entioned by Mr. Ilcwfcn, (Phil. Tranf. v. 58.) 



6. Nor 'do all the inteflinal abforbents feem to terminate in the 

 thoracic duel, as appears from fome curious experiments of I). 

 Munro, who gave madder to fome animals, having prcviouj 

 put a ligature on the thoracic duel, and found their bones and 

 the ferum of their blood coloured red. 



II. The Valves of the Abforhe*it Syjhm may fuffer their Fluids to re- 

 gurgitate in fome Difeqfes. 



1. The many valves, which occur in the progrefs of the lym- 

 phatic and lacleal vefiels, would feem infuperable obftacles to 

 the regurgitation of their contents. But as thefe valves are 

 placed in vefTeis, which are indued with life, and are themfelves 

 indued with life alfo \ and are very irritable into thofe natural 

 motions, which abforb, or propel the fluids they contain ; it is 

 poffible, in fome difeafes, where thefe valves or vefiels are flimu- 

 lated into unnatural exertions, or are become paralytic, that dur- 

 ing the diaflole of the part of the vefTel to which the valve is at- 

 tached, the valve may not fo completely clofe, as to prevent the 

 reiapfe of the lymph or chyle. This is rendered more probable, 

 by the experiments of injecting mercury, or water, or fuet, or by- 

 blowing air down thefe vefTeis : all which pafs the valves very 

 eafily, contrary to the natural courfe of their fluids, when the 

 vefTeis are thus a little forcibly dilated, as mentioned by Dr. Hal- 

 ler, Elem. Phyfiol. t. iii. f. 4. 



" The valves of the thoracic duel are few, fome afTert the' 

 are not more than twelve, and that they do not very accurately 

 perform their office, as they do not clofe the whole area of t 

 duel, and thence may permit chyle to repafs them down'.v 

 In living animals, however, though not always, yet more frequent- 

 ly than in the dead, they prevent the chyle from returning. The 

 principal of thefe valves is that, which prefides over the infer- 

 tion of the thoarcic duel, into the fubclavian vein \ many have 

 believed this alfo to perform the office of a valve, both to ad mil 

 the chyle into the vein, and to preclude the blood from entering 

 the duel ; but in my opinion it is fcareely fufficient for this pur- 

 pofe." Haller, Elem. Phyf. t. vii. p. 22 >. 



2. The mouths of the lymphatics feem to admit water to pafs 

 through them after death, the inverted way, eafier than the nat- 

 ural one ; fince an inverted bladder readily lets out the water 

 with which it is filled ; whence it miybe inferred, that there is 

 no obftach at th« mouths of thefe veflels to prevent the regurgi- 

 tation of their 



I 



