OF THE ABSORBENT VESSELS. 141 



that they were known also to Herophilus. From the year 150 to 1622 no ad- 

 vance was made, except that in 1563 Eustachius discovered the thoracic duct, but 

 he remained ignorant of its use. In 1622, Aselli in Italy saw the lacteals by 

 chance, when demonstrating the recurrent nerves to some friends. Thinking 

 they were nerves, he at first paid no attention to them ; but, soon observing tnat 

 they did not pursue the same course as the nerves, and " astonished at the novelty 

 of the thing, he hesitated for some time in silence," while all the circumstances of 

 the controversy and quarrels of anatomists passed before his view. He had by 

 chance been reading Costaeus on this subject the day before, and, in order to ex- 

 amine the matter further, he "took a sharp scalpel to cut one of those chords, 

 but had scarcely struck it when," he continues, " I perceived a liquor white as 

 milk, or rather like cream, to leap out. At this sight, I could not contain myself 

 for joy, but, turning to the by-standers, Alexander Tadinus and the senator Sep- 

 talius, I cried out Eupma. ! with Archimedes, and at the same time invited them 

 to look at so rare and pleasing a spectacle, with the novelty of which they were 

 much moved. But I was not long permitted to enjoy it, for the dog now ex- 

 pired, and, wonderful to tell, at the same instant the whole of that astonishing 

 series arid congeries of vessels, losing its brilliant whiteness, that fluid being 

 gone, in our very hands and almost before our eyes, so evanished and disap- 

 peared, that hardly a vestige was left to my most diligent search." The next day 

 he procured another dog, but could not discover the smallest white vessel. " I 

 now," he says, with the same admirable naivete, " began to be downcast in my 

 mind, thinking to myself that what had been observed in the first dog must be 

 ranked among those rare things which, according to Galen, are sometimes seen 

 in anatomy." At length he recollected that the dog had been opened " athirst 

 and unfed," and therefore opened a third, after feeding him " to satiety." " Every 

 thing was now more manifest and brilliant than in the first case." He gave his 

 whole attention to the subject, and was so diligent that not a week, or certainly 

 not a month, passed without a living dissection of dogs, cats, lambs, hogs, and 

 cows ; and he even bought a horse, and opened it alive, " A living man, which 

 Erasistratus and Herophilus of old did not fear to anatomise, I confess I did not 

 open." 



Notwithstanding this discovery of distinct chylous vessels, a large number of 

 high authorities adhered firmly to the old opinion of Galen, that they were only 

 rnesenteric vessels. " There is not one among the doctors," we read in a letter 

 of Thomas Bartholin, written at Montpellier, during his journey to Italy, " who 

 acknowledges the lacteal veins, so wedded are they to the authority of Galen, fcr 

 which they contend as pro arts et focis, and disregard the experiments of the 

 moderns." Unluckily, he did not trace the lacteals to the left subclavian vein, 

 but fancied they went to the liver, distributing the chyle through it for sanguifica- 

 tion ; this organ, according to the established doctrine, receiving the chyle from 

 the mesenteric arteries and veins to convert it into blood. 



In 1 649, Pecquet, a physician at Dieppe, was removing the heart of a dog, 

 when he noticed a quantity of white fluid pouring from the upper cava mixed 

 with blood. He at first thought he had opened some strange abscess ; and, after 

 pressing first upon one part and then upon another, he compressed the mesentery, 

 whose lacteals were full of chyle, when instantly a large quantity of this poured 



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