44 ANATOMY OF THE LYMPHATIC SYSTEM. 



rally completely injected after the natural injection with five per cent. 

 Berlin blue, as described above. 



The efferent trunk of the posterior system is single on each side ; 

 it mounts obliquely towards the middle line, and opens into the 

 thoracic duct near .the point where the latter emerges from the dia- 

 phragm. Each system communicates with the corresponding one of 

 the other side by a few larger vessels. The vessels of each system 

 have the following characters : the large vessels possess valves and a 

 wall consisting of spindle-shaped endothelium ; they are situated 

 chiefly between the pleural serosa and the tendons, or in the depth of 

 that serosa. The capillaries that run into those vessels have no 

 valves, are provided with irregular excavations, and their wall consists 

 of sinuous endothelium. There are two kinds of capillaries : a, such 

 ones that chiefly lie in the pleural serosa, and are of a variable breadth ; 

 6, capillaries that lie only between the tendinous tissue. They run, 

 consequently, in a straight course, in two directions, so that we may 

 distinguish deep straight capillaries running in a circular direction 

 and superficial straight capillaries running in a radial direction. 

 These two kinds of straight lymphatic capillaries communicate with 

 each other generally at those points where they cross each other in 

 such a way that an extremely short commu.iication-branch exists 

 where their walls come in contact ; or it is not seldom seen that a 

 superficial straight capillary bends under a right angle, so as to con- 

 tinue its course as a deep straight capillary. The deep straight 

 capillaries represent the vessels of communication between the super- 

 ficial straight capillaries and the lymphatic vessels that lie in the 

 pleural serosa. As a rule, the deep straight capillaries, before they 

 join a lymphatic trunk, run a short distance, in a more or less wavy 

 course, between the tendon and the pleural serosa. 



The relation between the straight lymphatic capillaries and those 

 that lie between the tendon and the pleural serosa, or in the latter, 

 can also be very clearly demonstrated in preparations prepared in the 

 following way : the abdominal surface of the centrum tendineum of a 

 rabbit just killed, after having been exposed, is pencilled and covered 

 with water for a few seconds ; after that, the concavity of the centrum 

 tendineum is covered with a quarter or half per cent, solution of 



