THE LYMPHATIC VESSELS OF THE SEROUS MEMBRANES. 41 



to be met with. Most generally it is the case where a lymphatic 

 vessel accompanying a vein gives off a short side-branch, which ends 

 blindly in the form of a sac. Into this terminal lymph-sac there 

 exists an imagination of a system of blood capillaries belonging to 

 that venous trunk. There may occur a growth of the endothelium 

 of the one wall of the lymph-sac towards the wall of the opposite side 

 in the form of a cellular network, from which, on the one hand, young 

 cells become separated, and which, on the other hand, gradually comes 

 to resemble an adenoid reticulum. In this manner an endo-lymph- 

 angial nodule is consequently produced. The other form of develop- 

 ment of endo-lymphangial nodules and cords is also tolerably frequent, 

 the form, namely, where a lymphatic vessel accompanying a large 

 blood-vessel possesses a sacciform dilatation in which a number of 

 capillary blood-vessels lie. By the outgrowth of the endothelial wall 

 of the lymphatic, in form of a cell network, towards the lumen of the 

 sac, an endo-lymphangial nodule or cord is formed. 



(b.) The Lymphatic System of the Centrum Tendineum of the 



Diaphragm. 



Eecklinghausen was the first to assign to the lymphatic vascular 

 system of the centrum tendineum an adequate importance, having 

 there previously demonstrated the lymphatics by silver and by natural 

 filling of these from the peritoneal cavity. Ludwig and Schweigger- 

 Seidel have amplified the results of Recklinghausen. My re- 

 searches do not only confirm those of the authors just mentioned, but 

 complete them to a considerable extent. 



I will first describe the methods by which the lymphatic vessels 

 of the diaphragm may be demonstrated. First, the method employed 

 by Eecklinghausen, that is, pencilling the pleural surface of the 

 centrum tendineum with a fine camel's-hair brush dipped into serum, 

 and subsequent staining the centrum tendineum with half per cent, 

 of silver-solution. By this method the lymphatic vessels of the 

 pleura serosa are shown. 



To obtain perfect preparations of these lymphatics, the following 



