ORGANS OF THE BODY. 



529 



form these vasa recta gives rise in many instances to vascular tassels or 

 bundles. 



The confluence of the returning, straight 

 venous vessels (fig. 522, ?w), takes place in a 

 manner precisely similar. They commence 

 partly as loops and partly as capillaries of the 

 medulla. Others, too, spring from a special 

 capillary network of larger tubes, situated at 

 the apices of the papillae (o). They empty 

 themselves finally into the arching veins, 

 already mentioned above, as lying at the 

 boundary between cortex and medulla. 



All earlier efforts to inject the lymphatic* 

 of the kidnev, by the method of puncture, 

 were unattended with success, and it was not 

 until Ludwig and Zawarykin had invented 

 a peculiar mode of procedure that it was 

 effected. The kidney chosen to be operated 

 on was that of the dog. 



The lymphatic canals of the parenchyma 

 occupy the interstices of that areolar tissue 

 which we know to exist immediately under 

 the capsule of the organ (fig. 512,^). Here 

 they communicate externally with other ves- 

 sels of the fibrous envelope, and penetrate 

 internally through interstices in the connec- 

 tive-tissue strom a, passing between the urini- 

 ferous tubes and around the capsules of Bow- 

 man and finer blood-vessels towards the 

 deeper portion of the organ. But though in- 

 tercommunication between the lymphatics of 

 the cortex exists very freely, the fine absorbent 

 vessels of the medullary processes can only 

 be filled with some difficulty, and still later 

 those of the medulla itself. The whole arrangement, indeed, resembles, 

 to a great extent, that of the lymphatics of 

 the male generative glands, the testes, to be 

 referred to again below. The canals collect- 

 ing the lymph in the cortex take precisely 

 the same course as the blood-vessels towards 

 the hilus. They only commence to present 

 valves in the vicinity of the latter, where 

 several very large trunks may be seen. 



The nerves of the kidney belonging to the 

 sympathetic system, and springing from the 

 plexus rehalis, enter with the arteries of the 

 organ. Their course and mode of termina- 

 tion, as well as their relations to the pro- 

 cesses of secretion, are however entirely un- 

 known. 



The development of the organs, as investi- 

 gated by Remak, takes place from the lowest part of the intestinal 

 tube, in the form of hollow buds, composed of a portion of the intes- 





Fig. 527. A deepiy-seated 

 rulus, TH, m, from the kidney of 

 the horse, a, arterial twig ; a /, 

 vas afferent; m, glomerulus; e f, 

 vas efferent ol the latter, dividing 

 at b into branches for the urini- 

 ferous tubuli of the medullary sub- 

 stance. 



Fig. 528. From the boundary layer 

 of the human kidney, a, arterial 

 twig; c, branches of the same 

 bearing at c and rf, as vasa affe- 

 rentia, two glomeruli ; /, another 

 branch (arteriola recta) breaking 

 up into long capillary meshes of 

 the medullary substance. 



