200 EPITHELIAL GLOBULES. 



lium), but also in the different kinds of connective tissue, 

 which constitute the interstitial tissue of the various or- 

 gans. 



It has been also discovered that in several parts, even in 

 the lymphatics of the surfaces, the connection between the 

 original spaces and the epithelium is not so close as former 

 methods of investigation had led us to suppose: "in all these 

 parts examination of the transparent section of the lymphatic 

 vessels, after injection of nitrate of silver, shows plainly that 

 they are not absolutely situated on the surface of the dermis ; 

 as injection of them, and the exaggerated distention caused 

 by the mercury, seemed to show. Teichmann and Belajeff 

 have proved that the entire capillary blood network is always 

 placed above the origin of the lymphatics which, taken to- 

 gether, also form the upper network of the integuments." 

 (Ch. Robin.) Belajeff meanwhile notes that some lymphatic 

 vessels of the urethral mucous membrane advance even to its 

 surface, so as to touch the epithelial polyhedral cells between 

 the papilla?, at their base (!) ; this appears to be the case, 

 also, in portions of the skin of rabbits, the dermis of which is 

 very thin. 



At all events, the perivascular spaces of the lymphatic 

 vessels are closely connected with the capillary system of 

 bloods-vessels ; in some parts the relation between them is 

 still closer, and the lymphatic and blood capillaries are placed 

 so near each other that, in a section of one of these meshes, 

 we find the lymphatic space surrounding half or two-thirds 

 of the circumference of the blood-vessel : " the lymphatic 

 space has a genuine coat only on one side, being bounded 

 on the others by the blood capillary " (Onimus). 



The most signal instance of this arrangement is found in the 

 perivascular spaces which Ch. Robin (1858) and His (18G3) 

 have described as existing around the vessels of the enceph- 

 alon. (Lymphatic sheaths of Robin and His.) These are 

 tubes, with thin coats and well defined hyaline boundaries, 

 surrounding even the finest capillary vessels, in the white and 

 gray matter of the cerebro-spinal centres, and in the pia 

 mater : this sheath is not, however, found around all these 

 vessels. Their appearance and contents, which consist of a 

 fluid, containing several spherical nuclei (globulines) lead us 

 to believe that these sheaths must belong to the system of 

 lymph spaces, " as they would otherwise form, in addition to 

 the lymphatic, arterial, and venous systems, a fourth vascu- 

 lar system whose terminations and nature would remain 



