44:8 ABSORPTION. 



The earlier physiologists, who supposed that all the pro- 

 ducts of digestion entered the system by the thoracic duct, 

 attached a great deal of importance to experiments showing 

 the effects of shutting off the chyle from the vascular system, 

 by tying or destroying this great canal. A number of very 

 interesting cases of obliteration of the thoracic duct in the 

 human subject has also been reported by Astley Cooper, 

 Andral, and others. ' In three cases observed by Cooper, the 

 duct was found completely obstructed ; and in two, he was 

 able to follow out anastomosing lymphatic branches, which 

 carried the chyle past the obstacle, so that its passage to the 

 venous system was not interrupted. In the remaining case, 

 the obstruction was accidentally discovered in a subject that 

 had been so far dissected as to render it impossible to ascertain 

 whether or not any anastomosing vessels existed. 1 In^a case 

 of obliteration of the thoracic duct, reported by Andral, the 

 canal had become an impervious cord for a considerable por- 

 tion of its extent, but there was a large vessel, like a seconc^ 

 thoracic duct, which extended from below the obstruction, 

 opening into the duct a considerable distance above, so that 

 the flow of chyle was not in the least interrupted. 3 



In nearly all the experiments which have been performed 

 upon the lower animals, ligation of the thoracic duct has 

 been followed by death, except where large communicating 

 vessels were found to exist, which would allow of the pas- 

 sage of the chyle into some part of the venous system. 

 Lower tied the duct in dogs, and the animals survived but a 

 few days. 3 In the experiments of Cooper, three dogs, out of 

 four which were operated upon, died from rupture of the 



1 ASTLEY COOPER, Three Instances of Obstruction of the Thoracic Duct, with 

 some Experiments showing the Effects of tying that Vessel. Medical Records and 

 Researches selected from the Papers of a Private Medical Association, London, 

 1798, p. 86 et seq. 



2 ANDRAL, FILS, Recherches pour servir' d VHistoire des Maladies du Systeme 

 Lymphatique. Archives Generates de Medecine, Paris, 1824, tome vi., p. 505. 



3 LOWER, Tractatus de Corde, item de Motu et Colore Sanguinis, ct Chyli 

 in cum Transitu. Amstelodami, 1(569, p. 220 et seq. 



