LYMPHATIC SYSTEM. 



cessfully injected preparations of the lymphatics in the che- 

 lonian reptiles, show almost every organ of their body, to be 

 permeated and covered over with a compact layer of these 

 wide absorbent vessels. They are remarkably crowded on 

 the surface and in the interior of the spleen in the chelonia, 

 as in the amphibia ; and Tiedemann supposed that all the 

 chyliferous vessels of the mesentery in these cold-blooded 

 classes, pass through the spleen before entering the thoracic 

 ducts. The thoracic ducts form generally two wide irregular 

 anastomosing canals, most dilated at the receptaculum, 

 which convey the lymph and chyle to the veins of the neck. 



The lymphatic glands or ganglia are not yet developed in the 

 reptiles, and their place is supplied by the tortuous windings 

 and subdivisions of parts of the vessels themselves, as in the 

 lower cold-blooded vertebrata, which indeed is but a less 

 concentrated or a more unravelled and simple condition of 

 the compact lymphatic ganglia of higher animals. Panizza 

 detected a small pulsating muscular sac on the lymphatics 

 proceeding from the posterior part of the trunk on each side, 

 in the coluber flavescens, like those discovered in the amphi- 

 bia, and they are found in many of the saurians ; they are 

 nearly an inch long in the python. He has not been able, 

 by all his injections, to discover a single direct entrance of a 

 lymphatic vessel, or of a lacteal into a vein, even in the 

 lymphatic and mesenteric glands of the higher vertebrata, 

 and he ascribes the communications pointed out by other ob- 

 servers, to the rupture of vessels, and the extravasation of 

 the injected matters, especially in the glands, where the 

 minute lymphatic capillaries twine round and interlace with 

 the veins. The more recent researches of Muller and other 

 anatomists have also tended to establish the isolated condi- 

 tion of the absorbents, in all the vertebrated classes, through- 

 out their entire course to the great normal trunks by which 

 they terminate in the venous system ; and Duvernoy sup- 

 poses that such free communications as have been presumed 

 between absorbents and veins, at least between the lacteals 

 and the branches of the vena portoe, would tend to dimmish 

 and deteriorate the chyle destined to nourish and replenish 

 the blood, by expending its principal constituents in the for- 

 mation of bile. 



The spleen of the tortoise, by successful injection, is made 



