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Show Orifice: of [be Laciezzls and Lympbafirs. Orificcs (yo tbs Luctmls and Lymp/Jatir's. 54 then, had not the advantage of these instruments, they could not possibly see the termination of arteries in veins; indeed, they never once suspected see any such termination, as it is now understood, much less could they been has as veins, the and arteries; of branches cxhalcnt the of orifices the already proved, have noinhalent orifices. Some of the modcrns have, from anatomical injections of arteries and veins in the dead body, inferred the cxhalent orifices of arteries and the inhalent orifices of veins. How little these injections are to be depended on, I have already" shewn, and that the fluid injected, escaping into cavities and surfaces, from the arteries and veins, might be by transudation only. Others have asserted, that they have actually seen these orifices by means of the microscope, and have either seen the injected iluids mu out from them on surfaces, or hanging in their mouths. Among these are Leiberkuhn and Mekel. The former inserted injecting tubes into the trunks of the arteries and veins of the in- testines, fiiled these with fluids coloured differently, and, having exposed the villi belonging to these arteries and veins to the microscope, by gradu- ally elevating the tubes from a horizontal to a perpendicular state, says he saw the fluids, by their own gravity, appear in the arteries and veins, and presently run out, at their cxhaling and inhaling orifices, into the cavities of‘thc ampullula: or bulbotts beginnings of the lacteals. His words are: " Nonnulli auteur rami arteriarum ct venularum supra descriptarum, trun- culis his suis lonqe ntinores, perforant hululani lactci, ct in hanc, apertis transferred to the skin, appear to prove, that there must be such orifices there, and of course every where else. Now it may be proved, that the discharge of blood referred to is, in the first place, from the arteries; and, in the next place, is not from rupture of those vessels. That the sweat is discharged by the arteries, is past doubt: they are the only vessels which carry fluids towards the skin. The red veins and lymphatics have their fluids passing in the opposite course, that is, towards the heart, or centre of the vascular system. If blood is discharged with the sweat, it must be from the same vessels which throw out that fluid. That the menstrual flux is a discharge from the arteries ofthe uterus, was an observation first made by Dr. Hunter. No where are arteries more easily distinguished from veins, than in this viscus: the arteries are there convoluted or curling; the branches of the veins are much larger, and are not convoluted. It happened that a woman died when her menses were flowing: Dr. Hunter examined the internal surface of the uterus, found it exceedingly red, and loaded with blood; that the principal redness was from the distended and convoluting arteries. Hc pressed forward the blood, which was fluid, and which, he asserted, never coagulated, and saw it appear on the surface near the extremities ofthese arteries. As this discharge happened instantly, and from the gentlest pressure ofthe finger, it could not be transudation, which always requires time; it could not be rupture ofa vessel, or vessels. 1 have had several opportunites ofrepeating this experiment, which always succeeded in the same manner. And again, speaking of the same vessels, he says: " Ramulus arteriolze in cavuru ampullula vasis lactei pcnctrans-Venosum ra- 55 Now, if this discharge is from the arteries osculis, hiant." in the uterus, there can be little doubt but that it is also from the arteries, when it is transferred to the skin.--'l‘hat neither of the discharges is from ruulum in cavtun ampullula: laCLCi liiantcm."-As it is certain, however, ruptured vessels, is demonstrated from the regularity of the pheenomcua. that he was deceived respecting the ampullula itself, so it is certain he must In the transferred menses (which I have seen more than once, and have have been respecting these orifices. I have injected the villi of the human been informed by Dr. Hunter that he had seen several times, besides that intestines with quicksilver to the greatest ntinuteness, but never saw a par- ticle pass out from the extremities ofthc blood-vessels. Professor Meltel's absorption by red veins has already been disproved. If the orifices of the exhalcnt branches of the arteries have not been seen, it may be said, whence do anatomists infer that such orifices exist? I have already entered into this subject in my remarks on transudation, and shall only add, to what I have there said, that the phatnomcna of bloody sweat, and the menstrual flux, trans- it has been mentioned by Haller, Bocrltaavc, and others) the blood ap- pears gradually, continues to {low regularly and slowly, comes periodically at the usual time of the menses, lasts the common time, and gradually dis- appears. This could never be the case in liminorrhage from ruptured ve sel. Hence then the existence of cxhalent orifices in arteries is inferred. Now, |