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conveyed ; but brings forward the present set of experiments to cor- 

 rect that opinion, which he finds to be erroneous. 



Mr. Brodie having tied the thoracic duct in some experiments of 

 his own, it occurred to Mr. Home, that under these circumstances 

 the existence or non-existence of any other channel from the stomach 

 into the circulation might be fully established. 



A rabbit and a dog were each subjected to this experiment. After 

 tying the thoracic duct, a quantity of infusion of rhubarb was inject- 

 ed into the stomach ; and, in an hour after, the urine was examined, 

 and found to be tinged with the rhubarb. In the dog, the bile was 

 also examined, and found to be tinged with the rhubarb. The exist- 

 ence of a channel distinct from the thoracic duct being thus esta- 

 blished, the experiment was repeated on a dog whose spleen had 

 been removed four days previously ; but still the urine became tinged 

 with the rhubarb, so that the channel is not through the spleen. 



As it was possible (though not very probable) that the rhubarb 

 might, by some anastomosis, obtain a passage through the lymphatic 

 vessel, which enters at the angle between the jugular and subclavian 

 veins on the right side, the same experiment was repeated upon an- 

 other dog, in whom this vessel was also secured by ligature, as well 

 as the thoracic duct, previously to the injection of the rhubarb ; but 

 in this experiment also the rhubarb found its way to the bladder, as 

 before. When the spleen of this dog was infused in water, the in- 

 fusion was slightly tinged with the rhubarb ; but when the liver was 

 infused, the proportion of blood present was so great as not to admit 

 of determining whether rhubarb was present or not. 



In some of these experiments the thoracic duct was wounded or 

 ruptured, so that chyle was found to have flowed from it, and was 

 collected for experiment : in other experiments the duct itself, the 

 mesenteric glands, and lacteals, were found distended, and the fluid 

 was pressed from them for the same purpose ; but it was in no in- 

 stance found to be tinged with the rhubarb. 



These experiments, says Mr. Home, completely establish the fact, 

 that the rhubarb did not pass through the thoracic duct, and also 

 completely overturn the opinion of the spleen being the medium by 

 which it was conveyed. He conceives, therefore, that the rhubarb 

 found in the spleen must previously have entered the circulation, and 

 thence have been deposited, by secretion, in the cells of the spleen. 

 The objection to this opinion is, that there is no excretory duct from 

 the spleen ; but Mr. Home observes, that the lymphatic vessels pro- 

 bably perform the office of excretory ducts, as they are both larger 

 and more numerous than in any other organ of the body. In the 

 ass, he remarks, they unite and form one common trunk ; and as 

 they terminate in the thoracic duct, it would be a deviation from the 

 general plan of the animal economy if their structure differed from 

 that of other lymphatic vessels. 



