144 DR. E. KLEIN AND PROFESSOR J3URD0N SANDERSON. 



vessels of tlie fissures form the only channels of communi- 

 cation between the anterior and posterior lymphatic systems. 

 Each of these systems communicates Avitli the corresponding 

 one of the other half by means of larger vessels, furnished 

 with valves aj;id lined with spindle-shaped endothelium, which 

 run between the serous covering on the pleural side and the 

 tendinous tissue. 



In the neighbourhood of the median line of the anterior 

 quadrant, and in the neighbourhood of the large vessels 

 which pierce the diaphragm, some of the vessels of the fis- 

 sures unite with some sinuous capillaries forming a net- 

 work, which like those of the pleural side are dilated into 

 sinuses. These lie more particularly between the serous 

 covering of the abdominal side and the tendinous tissue. 

 In the neighbourhood of the spot just mentioned two of the 

 superficial vessels of the fissures may be seen to be united by 

 a transverse branch belonging to the abdominal serous covering, 

 and this branch is also dilated into sinuses. 



All the fissures between the tendinous fasciculi do not 

 contain lymphatic vessels ; some, on the other hand, contain 

 only blood-vessels, and others a network of cells, of which 

 more will be said presently. The vessels of the fissures 

 communicate "with the free abdominal surface by means of 

 " perpendicular lymph-canals." These are short, for the 

 superficial vessels, longer for those Avhich are situated deeper 

 down. A canal of this kind sometimes passes directly through 

 one of the superficial vessels of the fissures and only opens 

 into a deeper one. The canals are lined at their free orifices, 

 which are true stomata, by an endothelium which looks 

 younger than that of the surface, is evidently granular, and 

 nearly cubical. This endothelium is continuous on the one 

 side with the flat endothelium of the vessels of the fissures, 

 on the other side with that of the serous surface. Each of the 

 vessels of the fissures possesses a number of such perpen- 

 dicular canals, which are arranged in rows one behind the 

 other. Moreover, perpendicular canals of this kind with a 

 free orifice are found not only in connection with the vessels 

 of the fissures, but Avith the serous lymph-capillaries of the 

 abdominal side as well. 



The arrangement of the lymphatic vessels of the centrum 

 tendineum might thus be compared to a pump with two 

 cylinders ; the one cylinder corresponding to the pleural 

 vessels of the anterior system, the other to those of the 

 posterior system ; Avhile the pipes connecting the two cy- 

 linders are represented by the vessels of the fissures, and the 

 piston tube by the perpendicular lymph-canals. 



