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Show The V(112w (y [be Lac/£1115 and Lynzpbatics. 64 65 The Valt/cs of the Lacteals and Lynzpbatics. Anger not only occa- that one of the first diseoverers of lymphatics was almost intirely ignorant of the valves ; and that, after the vessels themselves had been described, both by sions a similar determination of blood to the face, but quickens and makes Bartholin anti Rudbeck, the dilucidalio valvulm'zun should have been left for irregular the pulsations of the heart and arteries. The veins do not appear to have so much intercourse with the nerves as the arteries; and the reason, Ruysch. Bartholin, in his first publication on the lymphatics, says, " Val- vula tenerrimae texturze ingressui in axilarcm supra prmponitur, qua regres- surz aqua: obstat. liaque sol-a observari potest. Non dubito quin alibi quoque venis aquosis apponantur valvulae, siqttidem ne flatum admittant versus extremum immissa, ob tunica: tamcn subtilem contextum, cultro anatotnico scparari, non possunt." Ruyseh also censures Rudbeck, for being equally ignorant on this subject; though in the first edition of his works, which I have met with, he appears to me to treat. of it clearly. " Intus excavata et (istulosa sunt infinitas habcntia valvulas semper vesiculam cliylosam sive ejus ductus adspieientia, ne humor a glandulis vel aliis partibus exsuctus iterum refluat, quod aprime ligatura ostendit." Ruysch, how- In the one state it becomes red, in the other pale. Iapprehend, is, that the veins are more passive, and their action is in a great measure governed by that of the arteries; of course, so great an In- tcrcourse with the nerves was not necessary. The thoracic dttct is surround- ed through its whole length with the ramifications of the par vagum and inter- costal, but what influence they have on its action I do not know. It did not appear, in Haller's experiments, that any application to the thoracic duct or lymphatics gave pain; and we have already mentioned, that the lacteals performed their functions when the nerves were tied up. Red lines, from the absorption ofpoison, are sometimes tender to the touch; but this is from the inflamed skin, and not from the lymphatic vessel. Wounds of these vessels are frequently accompanied with symptoms of irritation, as shivering, sickness, and vomiting, but with no other pain than what must necessarily follow from pricking some smaller nerves at the same time. These vessels, like arteries and veins, are occasionally elongated or shortened, shoot into and ramify through neighbouring parts, and are again withdrawn: the former we infer from the circumstance of parts growing to one another, in such a manner, that the vessels of either part, though for- merly unconnected, may then be injected from the other; that blood coagu~ lating shall become vascular from the neighbouring vessels: the latter we infer from the circumstance of solid tumours occasionally disappearing in the living body, with the vessels which nourished them. C H A P. XIII. ever, has generally been considered as, if not the discoverer, the best demonstrator of the valves. Valves are an apparatus nature employs frequently, for the purpose ofprevcnting the retrograde motion of fluids, but no where so much as in the cavities of lacteals and lymphatics. The valves ofthe heart are mentioned even in Hippocrates's works. I shall not en- quire whether the book arsgi xxpaling, be genuine or not: the author, who ever he is, compares them to a spider's web, and says, "tot/09 agaxml: he appears also to have known the valves of the aorta, and pulmonary arte- ry, each of which he compares to a semicircle, ital/70oz mic/Ms. It is not evident that the ancients knew the valves of the veins; Fabricius was the first who engraved them, and shewed them to Harvey, who received from them his first idea of the circulation of the blood. As the valves ofthe arte~ ries and veins have been considered by anatoniists as productions of their internal coats, it may have been expected that I should have treated of the valves of lymphatics in the last chapter; but it never struck me as a good argument, that because one substance was seemingly continued from or went into another, it was therefore the same kind of substance; for if this TIM Valves (j the Lac/mls and Lympbm'im. As soon as an absorbed fluid has got alittlc way within a lacteal or lymphatic, it is prevented frotn returning by valves. One is surprized to find, that was true, muscle, tendon, and bone, would be similar substances-~21 con- clusion which needs no refutation. A lymphatic valve is a semicircular membrane, or rather ofa parabolic shape, attached to the inside of the lyin- K phatic |
