| OCR Text |
Show 26 Experiment: demonstrating that red VFIZIS do not absorb. Erprri'nmzis civilians/raring fbat red Vail/s do not absorb. veins, in the living, body, is subject to frequent retardation, on sneezing, roughing, straining, or any great effort; and they are thusmuch dilated be- yond what they were originally. Ifthey had not been larger, these retarda- tions would have more, frequently ruptured them. the blood in the vei Besides, the. quantity of is liable to greater variation than it is in the arteries. The cutaneous veins are turgid in summer, and almost totally Contracted in winter, so that in many cases they do not contain the. twenty-fifth part of blood in the one season as they do in the other. The velocity of the arterial blood being greater than that of the venous", it was also necessary, on that account, that the veins should be larger, even without any supposed absorption of lluids by them,- therefore the red veins of the intestines, and mcsentcry of quadrupeds, do not absorb, and every thing we have observed in the corresponding parts, in the human body, lead us to the same conclu- sions. The lacteals have been repeatedly seen turgid with cliyle, iii the ill- testines and mesentery of the human body; but I never saw, on such occasions, the least mixture of cliyle, or tingeofwliite fluid, in the blood of the mesentcric veins. I mentioned, in the last chapter, Swammerdam's hav- 1%!!le ing seen the blood in the mesenteric veins streaked white. Ialso mentioned, that Professor Mekcl informed us, that he had seen white lynip h in the same veins. I have frequently seen this appearance in the veins of the intestines: what this is owing to, I do not know; it cannot be absorption of chyle from the cavity ofthe intestines, for then the lactcals would also be found to contain the same coloured lluid: but, on every oc ion, where I have seen this appearance in the veins, the lacteals were constantly empty. \Vhen blood has been taken from the veins of the arm, the serum has JSCI) l. ioilnd frequently white as milk. It has continuedin this state for months, in the same patient; and at last recovered its natural colour, without our being able to assrgn any good reason for the one change, or for the other. home hours after a full meal, blood, taken from tl \e veins of the arm, has appeared streaked With white lines, which we know is from the chvle, which was poured into them by the thoracic duct; but is no proof of these veins ‘ By 4 Dr Halcs' experiments, the force of 15 ti motion in the arteries to (it: tt iii the veins, It as Sixteen to one, nearly. having absorbed chyle from the intestines. zu'l'ego mm , 3-4;; .u».-v.~"vm~'-e€tw,fi. As the red veins then do not absorb in the intestines, it is not probable, nor does it appear, that they absorb any where else. The appearances which ltiaaw Boerhaavc saw, Iai‘ ter injecting water into the stomach and intestines of dogs, were ownig entirely to transudation. In the injection of the veins from the vesiculx SC-. minales, by Professor Mckcl, there must have been rupture of the coats ol the veins in some place or other; for though Iliave fifty times,,at least, injected the vesiculm scminalcs with quicksilver, a more penetrating fluid than melted wax, I never once met with the same appearance: besides, if injections find their way from cavities into the supposed mouths of veins, they should also have found their way into the orifices of the lymphatics, which here were not injected. But injections thrown into the intestines, or other cavities, in the dead body, never, that I could observe, get into the lacteals, or lymphatics, though we know their orifices to he really there: could this ha\ e taken place, all the absorbent system would long ago have been complcatly described. As to the injection of the veins from the cavity of the bladder, by the same anatomist, I can, account for that The lacuna‘ a ipearanee in another way, and perfectly satisfactorily. of the urethra, or the excretory duCts of glands opening on that surface, are continued a little way into the Cavity of the bladder itself, where they are still more delicate in theirtexture, and are easily ruptured, when in. ilated with air, or injected with quicksilver. I have injected the veins of the bladder repeatedly from these lacunae; and a paper lrom Mr. \Vatson is published by the Royal Society, on these very lacuna; where the audio; stinposes them to be the orilices oflyinphatics; and says, that he introduce and ab- bristles into drum-when they are ruptured, the veins, arteries, sorbents are tore at the same time; but the injection gets into the .V'Eliis‘, in injecting as the larger vessels. The appearances observed by Haller, [Orllflllslltlz‘ttlolly the dead body, are also certainly to be referred either veins (EOlIIlIltlIIIiwhich so ieadily takes place in the dead body, or to the paxstngoil )y eating with the extremities of the arteries, and the injections Lymphancsmllame, when they absoib POL the then relaxed exhalents. poison of tits sons, web as the venereal virus, cancerous‘mattcr, or the dca dISSCCUDIS in others, and myself by both received, ""ounds mad deg. 1‘) 2 having 27 audio», |
