237 times prove fatal;--the air being drawn in by the divided veins. If, however, the scruple of bile, or the same quantity of atmospheric air be injected into one of the branches of the vena porta, no apparent inconvenience is sustained. M. Magendie1 concludes, from this fact, that the bile and atmospheric air, in their passage through the myriads of small vessels into which the vena porta divides and subdivides in the substance of the liver, become thoroughly mixed with the blood, and thus arrive at the vital organs in a condition to be unproductive of mischief. This view is rendered the more probable by the fact, that if the same quantity of bile or of air be injected very slowly into the crural vein, no perceptible inconvenience is sustained. Dr. Blundell injected in this manner five drachms into the femoral vein of a very small dog, with only temporary inconvenience; and, subsequently, three drachms of expired air, without much temporary disturbance; and M. Lepelletier affirms, that in the amphitheatre of the École Pratique of Paris, in the presence of upwards of two hundred students, he injected thrice into the femoral vein of a dog, of middle size, at a minute's interval, three cubic inches of air, without observ ing any other effect than struggling, whining, and rapid movements of deglutition; and these phenomena existed only whilst the injection was going on. Since that he has often repeated the experiment with identical results,-"proving," he observes, "that the deadly action of the air is, in such case, mechanical, and it is possible to prevent the fatal effects by injecting it so gradually, that the blood has power to disseminate, and perhaps even to dissolve it with sufficient promptitude to prevent its accumulation in the cardiac cavities." From the experiments of Mr. Erichsen, however, the cause of death in such cases, would appear to be asphyxia." As liquids are frequently passed off by the urinary organs soon after they have been swallowed, it has been believed by some,-either that there are vessels which form a direct communication between the stomach and bladder; or that a transudation takes place through the parietes of the stomach and intestine, and that the fluids proceed through the intermediate areolar tissue to the bladder. Both these views, we shall hereafter show, are devoid of foundation. In animals, in which the cutis vera is exposed, or the cuticle very thin, nutritive absorption is effected through that envelope. In the polypi, medusa, radiaria, and vermes, absorption is active, and according to Zeder and Rudolphi,' entozoa, that live in the midst of animal humours, imbibe them through the skin. A few years ago, Jacobson instituted experiments on the absorbing power of the helix of the vine (Limaçon des vignes). A solution of prussiate of potassa was poured over the body. This was rapidly absorbed, and entered the mass of blood in such quantity, that the animal acquired a deep blue colour when sulphate of iron was thrown upon it. In the frog, toad, sala 1 Précis Elémentaire, 2de édit., ii. 433. 2 Medico-Chirurg. Trans. for 1818, p. 65. 3 Physiologie Médicale et Philosophique, i. 494, Paris, 1831. 4 Bérard, Cours de Physiologie, iv. 94, Paris, 1855. 5 Entozoorum Histor., i. 252, 275, Berlin, 1829. 6 Mémoir. de l'Acad. des Sciences de Berlin, 1825, and Tiedemann, Traité Complet de Physiologie de l'Homme, edit. Fr., p. 242, Paris, 1831. mander, &c., cutaneous absorption is so considerable, that occasionally the weight of water, taken in this way, is equal to that of the whole body. It will be seen hereafter, that the nutrition of the foetus in utero is mainly, perhaps, accomplished by nutritive absorption effected through the cutaneous envelope. II. ABSORPTION OF LYMPH OR LYMPHOSIS. This function is effected by agents, that strongly resemble those concerned in the absorption of chyle. One part of the vascular apparatus is, indeed, common to both,-the thoracic duct. We are much less acquainted, however, with the physiology of lymphatic, than of chyliferous, absorption. 1. ANATOMY OF THE LYMPHATIC APPARATUS. The lymphatic apparatus consists of lymphatic vessels, lymphatic 1. The axillary artery. 2. Axillary vein. 3. Brachial artery. 4. Brachial vein. 5. Primitive carotid artery. 6. Internal jugular vein. 7. Subcutaneous lymphatics of arm at its upper part. 8. Two or three of the most inferior and superficial glands into which the superficial lymphatics empty. 9. Deep-seated lymphatics which accompany brachial artery. 10. Lymphatics and glands which accompany infra-scapular blood vessels. 11. Glands and lymphatics accompanying thoracica longa artery. 12. Deeper-seated lymphatics. 13. Axillary chain of glands. 14. Acromial branches of lymphatics. 15. Jugular lymphatics and glands. 16, 17. Lymphatics which empty into subclavian vein near its junction with right internal jugular vein. glands or ganglia, and thoracic duct. The latter, however, does not form the medium of communication between all the lymphatic vessels and the venous system. 1. Lymphatic vessels. These vessels exist in almost all parts of the body; and have the shape of cylindrical, transparent, membranous tubes, of small size, anastomosing freely with each other, so as to present, everywhere, a reticular arrangement. They are never, according to Professor Müller, so small as the arterial and venous capillaries, and are, almost without exception, visible to the naked eye. G. R. Treviranus asserts, that their walls, like the areolar brane, and other tissues, are made up of minute elementary mem cylinders, of a diameter of from 0.001 to 0.006 millimètres, placed in a series, side by side and end to end, so as to constitute tubes which form networks, and open into larger lymphatic trunks. They are extremely numerous; more so, however, in some parts than others. They have not been found in the brain, spinal marrow, eye, or internal ear, bones, cartilages, or any non-vascular parts; but this is not a positive proof, that they do not exist in some of them. It may be, that they are so minute as to escape observation. In their progress towards the venous system, they go on forming fewer and fewer trunks; yet always remain small. This uniformity in size is peculiar to them. When an artery sends off a branch, its size is sensibly diminished; and when a vein receives a branch, it is enlarged; but when a lymphatic ramifies; there is generally little change of size, whether the branch given off be large or small. The lymphatics consist of two planes,-the one superficial, the other deep-seated. The former creep under the outer covering of the organ, or of the skin, and accompany the subcutaneous veins. The latter are seated more deeply in the interstices of the muscles, or even in the tissue of parts; and accompany the nerves and great vessels. These planes anastomose with each other. Fig. 70. This arrangement occurs not only in the limbs, but the trunk, and in every viscus. In the trunk, the superficial plane is beneath the skin; and the deep-seated between the muscles and the serous membrane that lines the splanchnic cavities. In the viscera, one plane occupies the surface; the other appears to arise from the parenchyma. The two great trunks of the lymphatic system, in which the lymphatic vessels of the various parts of the body terminate, are the thoracic duct, and the great lymphatic trunk of the right side. The course of the thoracic duct has been described already. It is formed of three great vessels;-one, in which all the lymphatics and lacteals of the intestines terminate; and the other two, formed by the union of the lymphatics of the lower half of the body. Occasionally, the duct consists of several trunks, which unite into one before reaching the subclavian Lymphatic Vessels and Glands of the Groin of the Right Side. 1. Saphena magna vein. 2. Veins on the surface of abdomen. 3. External pudic vein. 4. Lymphatic vessels collected in fasciculi and accompanying the saphena vein on its inner side. 5. External trunks of the same set of vessels. 6. Lymphatic gland which receives all these vessels. It ferent trunks from this gland; they become deep-seated external lymphatic glands of the groin. 9. A chain of four the genitals, abdomen, and external portion of the thigh. or five inguinal glands, which receive the lymphatics from is placed on the termination of the saphena vein. 7. Ef and accompany the femoral artery. 8. One of the more vein; but more frequently it is double. In addition to the lymphatics of the lower half of the body, the thoracic duct receives a great part of those of the thorax, and all those from the left half of the upper part of the body. At its termination in the subclavian, there is a valve so disposed as to allow the lymph to pass into the blood; and to prevent the reflux of the blood into the duct. We shall see, however, that its mode of termination in the venous system possesses other advantages. The great lymphatic trunk of the right side is formed by the absorbents from that side of the head and neck, and from the right arm. It is very short, being little more than an inch, and sometimes not a quarter of an inch, in length,--but of a diameter nearly as great as the thoracic duct. A valve also exists at the mouth of this trunk, which has a similar arrangement and office with that of the left side. The lymphatics have been asserted to be more numerous than the veins; by some, indeed, the proportion has been estimated at fourteen superficial lymphatics to one superficial vein; whence it has been deduced, that the capacity of the lymphatic is greater than that of the venous system. This must be mere matter of conjecture. The same may be said of the speculations that have been indulged regarding the mode in which the lymphatic radicles arise,-whether by open mouths or by some spongy mediate body. The remarks made regarding the chylous radicles apply with equal force to the lymphatic. It has been a matter of some interest to determine, whether the lymphatic vessels have other communications with the venous system than by the two trunks just described; or, whether, soon after their origin, they do not open into the neighbouring veins,-an opinion held by many of those, who believe in the doctrine of absorption by the lymphatics exclusively, to explain why absorbed matters are found in the veins. Several of the older, as well as more modern, anatomists, have professed this opinion; whilst it has been strenuously combated by Sommering, Rudolphi,' and others. Vieussens affirmed, that, by means of injections, lymphatic vessels were distinctly seen originating from the minute arteries, and terminating in small veins. Sir William Blizard' asserts, that he twice observed lymphatics terminating directly in the iliac veins. Mr. Bracy Clarke' found, that the trunk of the lymphatic system of the horse had several openings into the lumbar veins. M. Ribes, by injecting the supra-hepatic veins, saw the substance of the injection enter the superficial lymphatics of the liver. M. Alard' considers that the lymphatic and venous systems communicate at their origins. Vincent Fohmann' thinks, that the lymphatic vessels communicate directly with the veins, not only in the capillaries, but in the interior of the lymphatic glands. Lauth,' of Strasburg,who went to Heidelberg to learn from Fohmann his plan of injecting,announced the same facts in 1824. By this anatomical arrangement, 1 Grundriss der Physiologie, u. s. w., 2ter Band, 2te Abtheilung, S. 247, Berlin, 1828. 2 Physiological Observations on the Absorbent System of Vessels, Lond., 1787. Rees's Cyclopedia, art. Anatomy, Veterinary. Magendie, Précis, etc., ii. 238. 5 Du Siége et de la Nature des Maladies, ou Nouvelles Considérations touchant la Véritable Action du Système Absorbant, etc., Paris, 1821. 6 Ueber die Verbindung der Saugadern mit den Venen, Heidelb., 1821; and Das Saugadersystem der Wirbelthiere, Heft 1, Heidelb., 1824; and Mém. sur les Communications des Vaisseaux Lymphatiques avec les Veines, Liége, 1832. 7 Essai sur les Vaisseaux Lymphatiques, Strasbourg, 1824. Lauth explains how an injection, sent into the arteries, reaches the lymphatics, without being effused into the areolar tissue; the injection passing from the arteries into the veins, and thence, by a retrograde route, into the lymphatics. M. Béclard believed, that this communication exists at least in the interior of the lymphatic glands; and he supported his opinion by the fact, that in birds, in which these glands are wanting, and are replaced by plexuses, the lymphatic vessels in the plexuses are distinctly seen opening into the veins. Lippi' has made these communications the subject of an express work. According to him, the most numerous exist between the lymphatic vessels of the abdomen, and the yena cava inferior and its branches. So numerous are they, that every vein receives a lymphatic vessel, and the sum of all would be sufficient to form several thoracic ducts. Opposite the second and third lumbar vertebræ, the lymphatic vessels are manifestly divided into two orders:-some ascending, and emptying themselves into the thoracic duct; others descending, and opening into the renal vessels and pelves of the kidneys. Lippi admits the same arrangement, as regards the chyliferous vessels; and he adopts it to explain the promptitude with which drinks are evacuated by the urine. Subsequent researches have not, in general, confirmed the statements of Lippi. G. Rossi, indeed, maintains, that the vessels, which Lippi took for lymphatics, were veins. It would appear, however, that when Rossi was in Paris, he was unable to demonstrate, when requested to do so by M. Breschet, the very things, that he had previously figured and described. Panizza, too, affirms, that no direct union or continuity between the venous capillaries and lymphatics has ever been made manifest to the eye, either in the human subject or the lower animals:3 and, on the whole, the observations of Lippi as to the alleged termination of lymphatics in various veins of the abdomen have generally been either rejected as erroneous or held to refer to deviations from the normal condition. It is proper to remark, however, that, recently, Dr. A. Nuhn, Prosector at Heidelberg, has maintained, that there is a regular communication between the abdominal lymphatics and veins, and describes three cases of the kind which fell under his own observation. In two of these, the lymphatics opened into the renal veins; in the third into the vena cava. The article contains a good history of the views of different observers on the communication between the absorbents and veins. We are perhaps justified in concluding with Panizza, that anatomy has not hitherto succeeded in determining, with physical certainty, in what relation the sanguiferous and lymphatic systems stand to each other, at their extreme ramifications. M. Magendie' conceives the 1 Illustrazioni Fisiologiche, etc., Firenz., 1825. 2 Omodei's Annali Universali, Jan., 1826. Osservazioni Antropo-zootomico-fisiologiche, Pavia, 1833; and Breschet, Système Quain's Human Anatomy, by Quain and Sharpey, Amer. edit., by Dr. Leidy, ii. 43, 5 Müller's Archiv. für Anatomie, u. s. w., Heft 2, S. 173, Berlin, 1848. See on both sides of this subject, Müller's Handbuch, u. s. w., Baly's translation, 7 VOL. I.-16 |