276 



ABSORPTION. 



[CHAP. xxvi. 



and Panizza, that in birds, as well as in reptiles and fishes, there 

 are communications with the small veins at many points of the 

 pelvis and abdomen. Nevertheless, the evidence for such a com- 

 munication in the lymphatic glands is very unsatisfactory. The 

 more probable explanation of the fact above noticed seems to be, 

 that the brittle texture of the interior of the glands readily gives 

 way before mercury, and that then the minute veins, which are 

 more numerous than the arteries and less resisting, are the first to 

 receive the extravasated metal. 



Origin of the Lymphatics. We have before spoken of the origin 

 of the lacteals in the villi of the small intestines. The lymphatics 

 in other regions have been usually considered to arise in the 

 substance of the skin and mucous membranes, and on the surface 

 of the viscera by a plexus of somewhat variable character. In 

 the skin and elsewhere the meshes are very close and small, 

 while on the lungs they are much more open and the vessels 

 larger. The surface of the liver and spleen is overrun with 



Fig 171. 



Part of a ramification of a lymphatic of the under part of the tail of a tadpole, a. Simple 

 membrane, forming the wall of the vessel. 6. Prolongation or processes of this membrane. 

 c, d. Fatty granules attached to the inner surface of the membrane, and surrounding the nuclei. 

 e. A closed extremity of the vessel. /. Branched cell, just united to a corresponding extremity 

 g. Branched cell, on the point of coalescing with a capillary lymphatic vessel already formed. 

 Magnified 400 diameters. After Kolliker. 



a network of lymphatics of remarkable luxuriance. So far as 

 mercurial injection can inform us, these plexuses are the com- 

 mencement of the lymphatic system ; but we have been recently 

 made acquainted with a system of lymphatic vessels discovered 

 by Kolliker in the tail of the larvaB of batrachian reptiles, which 

 renders it probable that a still finer series exists in the higher 



