Letters 1 97 



LETTER VII 



To the distinguished and learned John Dan. Horst^ 

 principal Physician at the Court of Hesse-Darmstadt 



MOST EXCELLENT SIR, Advanced age, which unfits 

 us for the investigation of novel subtleties, and the 

 mind which inclines to repose after the fatigues of 

 lengthened labours, prevent me from mixing myself 

 up with the investigation of these new and difficult 

 questions : so far am I from courting the office of 

 umpire in this dispute ! I was anxious to do you a 

 pleasure lately, when, in reply to your request, I sent 

 you the substance of what I had formerly written to a 

 Parisian physician as my ideas on the lacteal veins and 

 thoracic ducts. 1 Not, indeed, that I was certain of the 

 opinion then delivered, but that I might place these 

 objections such as they were before those who fancy 

 that when they have made a certain progress in discovery 

 all is revealed by them. 



With reference to your letters in reply, however, and 

 in so far as the collection of milky fluid in the vessels 

 of Aselli is concerned, I have not ascribed it to accident, 

 and as if there were not certain assignable causes for its 

 existence ; but I have denied that it was found at all 

 times in all animals, as the constant tenor of nutrition 

 would seem to require. Nor is it requisite that a matter, 

 already thin and much diluted, and which is to become 



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fat after the ulterior concoction, should concrete in the 

 dead animal. The instance of pus, I have adduced only 

 incidentally and collaterally. The hinge upon which our 

 whole discussion turns is the assumption that the fluid 

 contained in the lacteal vessels of Aselli is chyle. This 

 position I certainly do not think you demonstrate satis- 

 factorily, when you say that chyle must be educed from 



[' Pecquet described the duct as dividing into two branches, one for 

 each subclavian vein.] 



