150 Miscellaneous, 



4, the oviducts, the deferent canals, and the cloaca, but the ovarv 

 and testicle have none ; 5, the peritoneum, which passes in front of 

 the kidney, is furnished with them, and they cease upon the outer 

 sides of this organ, but its proper substance is destitute of them ; 

 6, the heart, the intrapericardial portion of the branchial artery, 

 and the pericardium possess lymphatics, which unite with those of 

 the end of the oesophagus by trunks existing on the inner surface 

 of the pericardio-peritoneal duct. The surface of the suprahepatic 

 venous sinuses, that of the vena cava and its dilatations and sinuses, 

 and that of the branches of the vena porta and the corresponding 

 arteries are also provided with them. 



The lymphatics of the different regions of the body above enu- 

 merated discharge themselves, in the Torpedos, by one or several 

 orifices into two prismatic triangular reservoirs, with their inner sur- 

 face smooth and of serous aspect, and their cavity often traversed by 

 delicate fibrous bundles. These reservoirs open into the dilatations 

 which the vence cavce present in all the Plagiostomi before their 

 arrival in Monro's sinuses. 



The precise point of this opening cannot be absolutely ascertained, 

 as it varies a little, not only in different species, but even in different 

 individuals. In Torpedo and Acanthias it is in the posterior third 

 of the venous dilatation that the lymphatic reservoirs open, by one 

 or two apertures, of which the anterior is almost always smaller than 

 the other. There is no valve at these orifices, nor above them ; but 

 they are oval, elongated, narrower in front than behind, and cut 

 obliquely in the thickness of the venous wall, like that of the ureter 

 in the mucous membrane of the bladder. Hence the posterior part 

 of the orifice represents a sort of fold with a delicate, concave, trans- 

 parent margin, which, under the pressure of the blood distending 

 the vena cava, applies itself against the opposite wall, and prevents 

 reflux into the lymphatic reservoirs. 



In the species of Plagiostomi in which the dilatations of the two 

 vencB cavce communicate with each other by numerous orifices of 

 their common partition {Torpedo, Squatina, Galeus), it is at the 

 lower margin of the common perforated partition that this opening 

 of the lymphatic reservoirs takes place. In Torpedos of ordinary 

 dimensions the orifices are from one to three millimetres in diameter. 



The networks forming the origin of the lymphatics in the Plagio- 

 stomi are directly applied against the capillary blood-vessels. If 

 we imagine the section of a capillary, the primary lymphatic always 

 forms upon the sides of this vessel a canal which embraces one-half, 

 two-thirds, or sometimes three-quarters of the circumference of the 

 vessel. The lymphatic represents a canal which has a proper wall 

 only on one side ; for the rest of its extent it is bounded by the 

 capillary ; or at least, to be more exact, the proper coat of the lym- 

 phatic adheres intimately at this point to the outer coat of the capil- 

 lary, on a part of the circumference of the latter, without losing its 

 continuity with the other portion. The lymphatic vessels are thus 

 applied to the sides of the capillaries. But this arrangement is also 

 observed in voluminous vessels, especially arterial ones. 



