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« the mefenteric artery. Thefe laft mentioned laAeals, 

 " before they join thofe from the duodenum, receive froti 

 *' the reftum a lymphatic, which runs with the blood-vtfTcIs 

 •* of that gut. Into this lymphatic fome finali branches 

 *' from the kidneys feem to enter, which, coming from 

 ♦' thofe glands upon the mefentery of the reftim, at Ia!l 

 " open into its lymphatic?. At the root of the cot-liac 

 «' artery, the lymphatics of the lower extremities probably 

 •' join thofe from the inteftines. The former," he fays, " I 

 *' have not yet traced to their termination, though I have 

 «' dillinclly feen them on the blood-veifc's of the thigh ; 

 «' and in one fubjecl which I injeftcd, fome veflels were 

 *' filled, contrary to the courfe of the lymph, from the net- 

 " work neir the root of tlie cocliac artery. Tliefc vcfTcls 

 " ran behind the cava, and down upon the aorta, near 

 ♦' to the origin of the crural arteries ; and I prefume they 

 " were the trunks of thofe branches which I had fcen in the 

 " thigh. At the root of the coeliac artery, and upon the 

 «' contiguous part of the aorta, a net-work is formed by 

 " the lafteals and lymphatics above-defcribcd. This net- 

 " work confifts of three or four tranfverfe branches, which 

 •' make a communication between thofe which are lateral. 

 " In the fubjeft from which this defcription was taken 

 «' there were four. From this net-work arife the two 

 " thoracic dufls, of which one lies on each fide of the fpine, 

 " and runs upon the lungs obhquely up towards the jugular 

 «• vein, into which it opens, not indeed into the angle be- 

 " tween the jugular and fubclavian vein, as in the human 

 •' fubjeft, but into the infide of the jugular vein, nearly 

 •' oppofite to the angle. The thoracic dutl of the left fide 

 «' is joined bv a large lymphatic which runs upon 'he oefo- 

 '' phagus, and can be traced as far as the lower or glan- 

 '• dular part of that canal, from which part, or from the 

 " gizzard, it feems to iffue. The thoracic duiSts are joined 

 " bv the Ivmphatica of the neck (and probably by thofe of 

 " the wings), Jul where they opea into the jugular vein?. 



" The lymphatics of the neck generally confift of two 

 " pretty large branches on each fide of the neck, accom- 

 " panymg the blood-veff.ls. Thofe two branches join near 

 " the lower part of the neck ; and the trunk is in general 

 " as fmall, if not fmaller, than either of the branches. 

 " This trunk runs clofe to the jugular vein, gets on its in- 

 " fide, and then opens into a lymphatic gland. From the 

 " oppofite fide of this gland a lymphatic comes out, which 

 " pours the lymph into the jugular vein. On the left fide, 

 •* the whole of this lymphatic joins the thoracic du&. of the 

 " fame fide ; but, on the right, one part of it goes into 

 " the infide of the jugular vein a little above the angle, 

 " whilft another joins the thoracic duel, and, with that 

 " dudl, forms a common trunk, which opens into the in- 

 " fide of the jugular vein, a little below the angle which 

 •' that vein makes with the fubclavian. 



" To th's defcription it may be neceflar)' to add, that 

 •' though it be taken from one fubjecl, yet in three others 

 " of the fame fpecics, which I examined carefully, I faw 

 •' nothing which difagreed with it. I particularly atlenaed 

 " to the number of the thoracic du<£ls, fufpefting that 

 " poflibly in this fubject the two that I had feen might be 

 " only a variety, which is a clrcumftance that, as we are 

 " told, has occurred even in the human body. But in 

 " three others of this fpecies, which I likewife fuccefsfuUy 

 " injeded, I ftill faw two duAs ; and therefore I am in- 

 " clined to believe, that this is the conilant number. I 

 " likewife carefully attended to the veffels coming from the 

 " gland on the right fide ; and in the only two fubjefts in 

 " which the lymphatics of the neck were properly filled, 

 Vol. IV. 



B I R 



" I obfetT^ed that one part of it opened immediately into 

 " the vein, and the other joined the thoracic duft. In all 

 " the four fnbjeels I evidently faw that the thoracic duAi 

 " opened into the infide of t'>e jugular veins. 



" This fyilcm in birds differs moH from that of quad- 

 " rupeds, id. In the chyle being tranfparciit and colour- 

 " lefs ; idly. In t'-'ere being no vifible lymphatic glands, 

 " neither in the courfe of the lafteals, nor in that of the 

 " lymphatics of the abdomen, nor near the thoracc du&s ; 

 " ^^h'' I'l 'hir fevc-ral parts of this fyftem in birds being 

 " more frequently enlarged, or varicofe, than in quadrupeds. 

 '' In particular, this appears to be the cafe of the vefTcU 

 " which conftitute the net-work at the root of the coe'iac 

 " artery, in that fubjeft from which the drawing was 

 " taken. The lacteaU are frequently enlarged in fome 

 " places ; fo are the thoracic duels ; and the lymphatics on 

 " each fide of the neck are commonly, when taken to- 

 " gether, larger than their trunk, which opens into the 

 " lymphatic gland. In one fubjeft, when, inftcad of two 

 " lymphatics on the left fide, 1 found only one, that vcflel 

 " was as large as a crow quill, whilft the lower part of it, 

 " which entered the gland, was much fmaller." 



The figures which rxp'am the foregoing defci'ption are 

 to be found in Plate V. of the /Inatomy of birdr. Fig. l . 

 fliews the abforbents in their natural fituation, with rcfpeft 

 to the other parts of the body ; A, the neck ; B, B, the 

 clavicle divided near its middle j C, the left fubclavian 

 artery' ; D, D, the jugular veins ; E, E, the pulmonary- 

 arteries ; F, F, the two branches of the trachea ; G, G, 

 the lungs ; H, the aorta ; I, the cce'iac artery ; L, the 

 cefophagus turned to one fide ; M, M, the renal capfules ; 

 N, a fmall part of the liver fixed to a rib by a thread ; 

 O, O, O, inteftines ; P, the duodenum ; Q, the pancreas 

 fixed to a rib by a thread ; R, the gizzard. Fig. 2. ex- 

 hibits the abforbents, and their more immediate connexions 

 with the Veflels, in outlines : a, the laAeals or more pro- 

 perly lyrrphatics, which come from the duodenum ; b, the 

 lymphatics of the liver, N ; c, c, z plexus formed by the 

 above-mentioned laft.als and lymphatics, which furrounds 

 the coehac arter)', I ; </, a lymphatic from the gizzard ; e, 

 a lymphatic from, the lower part of the afophagui ; f,f, a 

 net-work formed by the lymphatics upon the aorta, H ; 

 g, g, the two thoracic dufts ; /, », the trur.ks of the lym- 

 phatics of the neck ; t, i, the glands through which the 

 lymphatic veflels of the neck pafs : that of the left fide is 

 oblong, and could not well be reprefented in a Figure ; /, the 

 thoracic duSt of the left fide, and the lymphatic veflrl of 

 the neck, opening together into the infide of the jugular 

 vein ; m, a part of the lymphatic of the right fide of the 

 neck, opening into the jugular vein, D ; n. the thoracic 

 duft of the right fide, joined by a part of the lymphatic 

 veflel of the right fide, and then opening into the infide of 

 the j\igular vein. 



ffeat-t. 



This organ occupies the centre of the fuperior portion of 

 the common cavity of birds. It is placed ufuallv in the line 

 of the body, as in quadrupeds ; the heart, however, is inclined 

 in the flighteft degree to the left fide in fome iuftances, and in 

 others a little to the right fide. The apex of the heart is com- 

 monly received between the two chief lobes of the liver, 

 which are hollowed out for its accommodation. 



The membranous bag, which contains the heart, is formed 

 like the pericardium of other animals, and is reflcAed in the 

 common manner upon the ongin of the great veflels, and the 

 heart. The pericardium of birds is generally confijerably 

 larger than the heart, and efpecially at the lower part, 

 3 F which 



