| OCR Text |
Show 52 Origin of the Lacteals and Lynzp/mtics. Orifice: (if tbs Lac/edls and Lymp/aalics. 53 quicksilver will not always return by the veins. I have injected the arte- ries of the intestines to the utmost with quicksilver, and yet not a particle has returned by the veins. 1 have reversed this, and injected the veins to under the pressure of a large column, gets into the absorbents. the utmost, and yet none of the quicksilver returned by the arteries. Are we, therefore, to infer, that the arteries and veins are not connected, after the urine into it from the kidneys; yet neither water, nor air, nor any other injection, will pass from the bladder into the ureters in their natural state ; this happens from the obliquity ofthc insertion of their orifices, which run for some way between the muscular and internal coats of the bladder, before they open into the cavity,- and we do not know that there may not be a similar contrivancc in the insertion ofthe mouths of lymphatics in the so many proofs that they Certainly are? Again it may be said, if lymphatics are connected with arteries, like veins, why are they not, like them, full in the dead body? The veins then become full, and contain almost all the blood which the arteries and they together contained during life. The reason of this is evident: the blood in the arteriesis not only propelled by the force of the heart; but the arteries continue to propel their con- tents, after the heart has ceased acting. As the veins are so much more capacious than the arteries, they easily contain the whole; and it must stagnate there, because, the lungs being collapsed, the blood of the pulmonary artery cannot get through, of course, it must remain full; and if it remain full, the right ventricle, for a similar reason, must do so too, and so must the right auriele, and thence the whole venous system. Now, if the lymphatics are connected with the arteries, why are they not also full in the dead body? In the first place, their connection with arteries is diffe- rent from that of the veins. The veins must receive the blood propelled If it gets in, we allow this doctrine; if it does not get in, it must fall to the ground! This does not follow. The ureters are inserted into the bladder, and bring cavities of arteries and veins; which conjoined to their not acting but from a particular stimulus, may fully solve the phatnomenon. The lymphatics, which arise from the interior surfaces of the arteries and veins, may have their orifices ofsuch a nature as to be capable of taking fluids into them, or shutting themselves, and not receiving fluids, except in certain circum. stances. It has already been shown, that it is very improbable that they are terminations of arteries, necessarily receiving fluids propelled by the force of the heart and arteries. by the arteries, and are in some sense passive; but absorbents have their CII A P. XI. orifices sometimes immersed in fluids for years, and take up none of them till a particular stimulus for absorption is given. This we have sometimes Orifices (3/1/36 Lacfmlr and Lymphatic-s. seen in the natural cure of ascites, when the absorbents of the abdomen have of their own accord, and without the least assistance from medicine, in two or three days removed the whole of the contained fluid, though no an. ancients Speak of the mouths of arteries and red veins, and of an absorption performed by these months, with great confidence. One would alteration had taken place for years before. In the next place, the absor- suppose, from reading the passages formerly quoted from Hippocrates and bents are still more irritable than the arteries. They continue to propel their fluids generally for some time after death,- and, as the veins are fully capable of holding their fluids as well as those of the arteries, the lymphatics tain, than that the naked eye does not (llSCOVCr any distinct terminations of are empty in the dead body, and may notwithstanding be connected with the arteries and the veins too, in the way I contend. A proof, it has been said, might easily be adduced :-l"ill the carotid, at that place where it is giving off no branches, with quicksilver, and let us see if any part of it, under Galen, that they had certainly seen them: nothing, however, is more cer- arteri s or beginnings of veins. These are lost in minuteness and number. The microscope only discovers some ofthese, in particular parts of living animals; it discovers the termination of arteries in veins, and of course, the beginnings of the veins: but the microscope itself has not enabled us to discover the orifices of the cxhalent branches of arteries. As the ancients, i then, |
