LYMPHATIC SYSTEM 



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vessels make a current in the larger lymph trunks, and finally the 

 whole of the lymph is returned to the veins by the several connexions 

 already mentioned. In addition to the propelling force of the lymph 

 hearts and the pressure due to absorption and osmosis, the lymph is 

 also carried along by the motions of the parts in which the vessels 

 ramify, their pressure being supplemented by the action of the valves. 



In all fishes which have been accurately studied the lymph system is well 

 developed (fig. 356), consisting of numerous trunks running through the body 



Fig. 356. — Deeper anterior lymphatics (stippled) of Scorpenichihys, after .\llen. a, 

 auricle; abs, abdominal sinus; b, brachial sinus; br, brain; cs, cephalic sinus; d, dorsal 

 trunk; fm, facialis-mandibularis vein; hs, hyoid sinus; ij, inferior jugular vein; ips, 

 inner pectoral fin sinus; j, jugular vein; /, lateral trunk; on, orbito-nasal vein; />, peri 

 cardial sinus; pf, profundus facialis lateral trunk; pv, profundus ventral trunk; sf 

 superficial lateral trunk; ssl, superior spinal longitudinal trunk; v, ventricle; va, ventra 

 aorta; vfs, ventral fin sinus; vp, ventral pericardial sinus; vt, ventral abdominal trunk. 



and head, these connecting with unpaired sinuses in connexion with the dorsal 

 and anal fins and between the pectorals. The system opens into the veins in 

 both the cardiac and the caudal and cardiac regions. In the caudal region 

 (teleosts, myxinoids) are larger cavities which are usually regarded as lymph 

 hearts, but this interpretation has been doubted in the case of the teleosts. 

 The mechanism of the caudal heart may be understood from figure 355. 



In the urodeles there are two subvertebral trunks, united behind, but separate 

 in front, which empty into the corresponding subclavian veins. Into these 



