ORIGINS OF THE LYMPHATIC VESSELS. 321 



cal impregnation of the tissues with insoluble colouring or other par- 

 ticles, and subsequently to stain them with silver, in order to establish 

 the fact that the absorbed material passes from the serous canals into 

 the lymphatic capillaries ; the evidence would be perfectly satisfactory, 

 were it possible to propel the particles, whilst the preparation is under 

 observation with the microscope, directly from the serous canals into 

 the lymphatics. I, however, venture to hold that the theory as above 

 stated affords an explanation of all the facts at present known, whilst 

 others are not equally comprehensive. In order to render this evident, 

 let us consider the facts on which the supporters of other views rely. 

 Ludwig and Tomsa, for instance, regard the fissures they have dis- 

 covered between the canaliculi of the testis as the origins of the lym- 

 phatic vessels, and they undoubtedly lie so close between the paren- 

 chyma, not unfrequently investing the bloodvessels, and the con- 

 nective tissue is withal so small in quantity, that it is scarcely possible 

 to look in this organ for other roots of the lymphatic vessels, that is, 

 for a serous canal system. Ludwig and Zawarykin injected similar 

 lacunae in the kidneys surrounding the tubuli uriniferi. Tomsa made 

 inj ections of the nose of the dog, and saw plexuses suddenly proceed from 

 the injected capillaries, which he regarded as transverse sections of 

 lacunae intervening between the muscles, or fasciculi of connective 

 tissue. At the same time, their fissure-like form was not demonstrated 

 by him, and both his illustrations and descriptions agree equally well 

 with my explanation, especially as it appears from them that fusiform 

 cells (connective tissue corpuscles) are found at the borders of the 

 injected canals. In the case of the kidneys, I have not been able to 

 convince myself that the lacunae in the tissue, serving as origins for 

 the lymphatic vessels, are fissure-like in form. In regard to the 

 lymph lacunae of the testis, whether they exist to the extent described 

 by Ludwig and Tomsa, or are less developed, they can afford no 

 evidence on the mode of origin of lymphatics in other organs ; for 

 His and Tommasi have demonstrated that they are lined by the cha- 

 racteristic epithelium of the lymphatic capillaries, and hence are most 

 probably analogous to these rather than to serous canals. The other 

 theory, which refers the rootlets of the lymphatic system to the con- 

 nective tissue corpuscles, rests on a fact which is also in full accordance 

 with my view ; namely, on the connection of the cells of the tissue 

 with the dentated rootlets of the lymphatic vessels (K6 Hiker). I cer- 

 tainly do not participate in the doubts entertained by many respecting 

 the lymphatic nature of these rootlets. It is true, indeed, that we 

 cannot ordinarily perceive any current traversing them, since the 

 fluid is as clear as water ; but in one instance I was able, after pro- 



