THE LYMPHATIC SYSTEM. 165 



that lie had discovered a system of canaliculi in connective tis- 

 sue, which he termed sap or juice canaliculi (saf tkanalchen). 

 His views, as modified somewhat later, are, that the connective 

 tissue is traversed by serous canaliculi or plasmatic channels 

 which are directly continuous with the lymphatic vessels. 

 "Not mere fissures in the connective tissue, but interstices of 

 the fibrous fasciculi and lamellae of connective tissue, cemented 

 to one another by a tenacious, homogeneous, firm material, in 

 which the serous canaliculi are buried." 



The lymphatics of the mesentery. A portion of the mesen- 

 tery between the trabeculse, taken fresh from a cat and stained 

 with nitrate of silver, exhibits on both surfaces an endothelial 

 layer, the cells of which possess an irregular outline, marked 

 by the deposit of silver, either in a supposed intercellular sub- 

 stance or in crevices between the cells. Sometimes this outline 

 is polygonal, sometimes sinuous, crenated, or even sharply den- 

 tated. It may be an even, fine line, or it may possess irregu- 

 larities as if beaded. At the union of these lines, that is, where 

 two or more cells terminate, a round, irregularly triangular, or 

 spindle-shaped spot may be often observed, which is stained 

 like the intercellular line, or in a lighter or darker shade. 

 There are other spots of larger size, presenting the appearance 

 of openings ; we shall refer to them again. The surface of the 

 cells may be clear, or granular, sometimes it is quite dark, vary- 

 ing with the degree of staining and the condition of the tissue ; 

 a nucleus can usually be seen at a slightly deeper level. This 

 is plainly visible in unstained or slightly stained specimens, or 

 where special reagents have been used to make the nuclei promi- 

 nent, as haematoxylin or picro-carminate of ammonia. The 

 granular appearance spoken of is sometimes confined to a series 

 of cells which surround a stoma, or the black spots mentioned, 

 while the neighboring cells may be clear ; in other cases, sev- 

 eral corpuscles in the form of an irregular tract may present 

 this appearance. 



Klein has observed cells which are club-shaped, undergoing a budding pro- 

 cess, i.e., giving off little bodies resembling lymphoid corpuscles. He has given 

 the term germinating endothelium to these cells. Other histologists have made 

 similar observations. 



Underneath and around the nuclei a delicate, intricate, re- 

 ticulum of elastic fibres may be seen plainly in unstained speci- 



