458 ANATOMY OF VEBTEBRATES. 



column, which combine with the lacteal plexiform trunks con- 

 tinued forward along each side of the stomach and oesophagus, 

 to form a large, short, common lacteo-lymphatic trunk on each 

 side, which terminates in the jugular vein near its junction with 

 the short precaval vein. Fohman ' describes other and minor com- 

 munications between the absorbent and venous systems of Fishes, 

 as, e. g., in the gastric and intestinal plexuses in the Sheat-fish 

 and Turbot. The lymphatic system of the caudal portion of the 

 body is chiefly received by two caudal sinuses, intercommunicating 

 by a transverse canal, which sometimes perforates the base of the 

 anchylosed compressed terminal tail-vertebra. 



The lymphatics of Fishes consist generally of a single tunic : 

 a most delicate epithelial lining may be distinguished in the 

 larger trunks. The only situations where valves have been seen 

 in these vessels are at the terminations of the trunks in the 

 caudal and the jugular veins. There are no lymphatic glands : 

 these are represented by the large and numerous plexuses, and 

 possibly by the gland-like layers or substances above-mentioned. 

 The chyle as well as the lymph of Fishes is colourless and 

 transparent : the plasmic corpuscles or lymph-cells are few in 

 number.^ The analysis of the lymph in Fishes is still a 

 desideratum. 



§ 80. Absorbents of Reptiles. — In the intestines of the Frog 

 and Salamander the lacteals form a network of large canals, 

 with minute or close meshes coextensive with the mucous 

 membrane ; the vessels continued therefrom accompany the 

 mesenteric arteries, sometimes forming a pair, running along 

 ojjpositc sides, with occasional connecting cross-branches ; more 

 commonly having these so numerous as to constitute a continuous 

 reticulate sheath about the artery, the cavity of which sheath 

 seems, in some parts, to be only partially divided by cross 

 threads.^ These lacteals, or intestinal lymphatics, open into a 

 receptacle at the dorsal line of reflection of the mesentery, of 

 large size in the Frog, but contracted and assuming rather the 



cv. 



man 



'- In CXLV. these lymph-corpuscles are descrihed as ' centres of assimilative force, 

 lanifesting inherent power of developcment and change, some being granular, others 

 ith a capsule and in the condition of nucleated cells,' p. 249 (1846'). Prof. KoUiker 

 testifies to the fissiparous multiplication of the lymph-corpuscles in the lacteals of the 

 dog, cat, and rabbit. The corpuscle, in the condition of the nucleated cell, elongates, 

 the nucleus divides into two ; between which the cell contracts and tinally divides 

 (ccLxii. p. C3I)). In Fishes the nucleus undergoes further subdivision before the 

 fission of the cells takes ])lacc. 

 " CCLVI. p. 249. 



