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Show Hula/y aft/ac Laciwls and Lymp/mtit'r. 3 . 33 His/my of HJK' LIICJINIIS and Lympbzztics. durt is frequently double; and has one insertion into the right subclavian vein, and another into the left. The older anatomists were not aware of this, audin theirlexpcriments tied up only the left subclavian and jugular veins. Besides the trunk already mentioned, in the anterior mediastinum, under the sternum, though often inserted into the termination ofthe thoracic duct, is sometimes also inserted into the trunk of the right side; in which, as I have already said, I have seen the ehyle. The same arguments maybe employed against the objection ofthe obstructed thoracic duct; and in what- ever point of view we consider this subject, there is not one solid argument in favour of absorption by red veins. as we shall afterwards sec, hardly any of the succeeding anatomists have had clear ideas on that subject. The anatomists seem to have paid very little attention to this discovery of Eustachius. He is said, by some, to have ascribed to this vein the func- tion of nourishing the thorax; but he himself expressly disavows any such idea, and says, " qumm‘ix mini/tit: sit ml tbarzzccm alu/tdam." It is not to be wondered, that they made but little enquiry about what he himself con, fesseshc did not understand. No more, therefore, of this system washeard of till the year 1622, when Asellius, an Italian anatomist, investigating the motion of the diaphragm in a living dog, in the presence of some medical friends, accidentally disco- vered white fibres on the incsentet‘y. C H A P. He took them at first for nerves; but observing, that after puncture they discharged a white fluid, and quick- ly became collapsed and invisible, he pronounced them to be new vessels. VI. Repeated experiments confirmed him in this idea. He went farther; he A ntt‘t'c jrrlriicular History ofibe Laclmls and Lympbalics. was not only the first who saw these vessels, knowing them to be different from arteries and veins, but he also, with much sagacity and penetration, He observed, that they were often invi- announced their peculiar office. E L? sr «.cu i u s, a Roman anatomist, was properly the first discoverer in [his sible on the mesentery, whilst the arteries and veins were at all times per- partofanatomy. fectly evident: that whenever the intestines contained chylc, these vessels ltappears, that about the year 1563, he saw the thoracic duct, or what is now known to be the trunk of the absorbent system, in a horse. He has particularly described it in his Treatise de Yena sine l'ari, where he calls it Vena Alba Thoracis. Of the left subclavian vein, he says, " Ab hoe ipso insigni trunco sinistro jugali qua posterior sedes radicis vcnm interim jugularis spectat mrtgna qmz'drtm pmpflgt) germinal, qum pre- terquam quod in ejus origine ostiolum semicircularc habet, est etiam alba ct aquart bumorisplena; nee longc ab ortu in duas partes scinditus, paulo post rursus coeuntes in unam, qua: nullos ramos dilfundens, juxta sitiistrtnn ver- tebrarum latus, pcnctrato scpto transverso, deorsum ad medium usque linu- borum fertur; (luo loco latior cffccta, magnamquc arteriam c umplexa, obscurissimum finem mihi adhuc non bene pereeptum obtinet." were always full of a similar white fluid. For these reasons he called them Vasa Lactca, and assigned them the oil-ice of absorbing chyle from the in- testinal tube, and carrying it into the blood. Before his time, the vcsselsof the human body, and of quadrupeds, were said to be of three kinds, arte- ries, veins, and nerves. Having discovered the lactcals, hc naturally terms them the fourth kind. " \r'asa mcseraica Galcnus ct omnes post cum anatomici paritcr et Inc- dici gencre triplicia faciunt venas, arteri' s, et nervos." " Aliud est genus quartum novum ac ignotum hactcnus, et a me primo observatum." r These vessels he discovered not only in dogs, but in a variety of otht From this quotation, it is impossible to doubt hishaving seen the thoracic duct; but, not uudcrstandiugit, he begins at its termination in the left sub- tlai tan \‘cm, and traces 1t downwards to its origin, where it is no wonder he was bettilder‘d , Since ' the art of 'iujtctt i i on was not then found out; and, as quadrupeds. He tells us, " Confirmatus gemino hoe experimento, ct nihil amplius dc l‘L‘ ipsa ambigens, totum me dedi ad perquircndam cam pcrctpt- cndamquc accuratius, in quam curam ita incubui nulla ut tcmcrc hepdunt‘a. F lit}, |