OF THE ABSORBENT VESSELS. 127 



they prove limpid on being let out ; and that when red substances 

 have been swallowed, and they look red, this arises from the 

 abstinence, which always causes the fluid of both lacteals and 

 lymphatics to become red. 



" The ultimate trunks of the lacteals, arising, like the lympha- 

 tics, from the combination of a great number of small twigs P, 

 unite into the receptaculum or cisterna chyli, the appellation by 

 which the lower and larger part of the thoracic or PECQUETIAN 

 duct is distinguished. 



" This duct is q a membranous canal," consisting of an external 

 fibrous, and a smooth inner serous coat, " slender, strong, more or 

 less tortuous, subject to great varieties in its course and division 1 ", 

 and possessing here and there valves. At about the lowest cer- 

 vical vertebra, after passing the subclavian vein, it turns back 

 again s, and is inserted into this, being furnished with a peculiar 

 valve at the point of insertion. 



a, receptaculum chyli. 



b, upper end of the thoracic duct, 



which bends behind 



c, the internal jugular vein, and 



terminates in 



d, the angle of the jugular and sub- 



clavian veins. 



e, vena azygos. 



P " Sheldon, I.e. tab. v." 



i " See Haller, Observations de ductu thoracico in theatro Gottingensi factec. 

 Getting. 1741. 4to. 



B. S. Albinus, Tabula vasis chyliferi. LB. 1757. large folio. 



Mascagni, tab. xix." 



r " See v. c. J. C. Bohl, Vies lactece. c. h. historia naturalis. Regiom.1741. 4to. 



Sommerring, Commentat. Soc. Scient. Gottingens. t.xiii. p. 111." 

 s " v. Haller, Opera, Minora, vol. i. tab. xii," 



K 2 



