375 



vatory, Ross-Bank, Van Diemen's Land, for April, May and June 

 1841." (Forms 1 & 2.) 



5. The reading of a paper, entitled, " On the Structure and Use of 

 the Malpighian bodies of the Kidney, with Observations on the Cir- 

 culation through that Gland." By William Bowman, Esq., F.R.S., 

 Demonstrator of Anatomy in King's College, London, and Assistant 

 Surgeon to the King's College Hospital, was resumed and con- 

 cluded. 



The author describes the results of his examination of the struc- 

 ture and connexions of the Malpighian bodies of the kidney in dif- 

 ferent tribes of Vertebrata, and shows that they consist essentially of 

 a small mass of vessels, contained within dilated extremities of the 

 convoluted uriniferous tubes. The tubes themselves consist of an 

 outer transparent membrane (termed by the author the basement 

 membrane) lined by epithelium. This basement membrane, where 

 it is expanded over the tuft of vessels, constitutes the capsule de- 

 scribed by Miiller. The epithelium lining the uriniferous tube is 

 altered in its character where the tube is continuous with the cap- 

 sule, being there more transparent, and furnished with cilia, which, 

 in the frog, may be seen, for many hours after death, in very active 

 motion, directing a current down the tube. Farther within the cap- 

 sule the epithelium is excessively delicate, and even, in many cases, 

 absent. The renal artery, with the exception of a few branches given 

 off to the capsule, surrounding fat, and coats of the larger blood- 

 vessels, divides itself into minute twigs, which are the afferent ves- 

 sels of the Malpighian tufts. After it has pierced the capsule, the 

 twig dilates, and suddenly divides and subdivides itself into several 

 minute branches, terminating in convoluted capillaries, which are 

 collected in the form of a ball ; and from the interior of the ball the 

 solitary efferent vessel emerges, passing out of the capsule by the 

 side of the single afferent vessel. This ball lies loose and bare in 

 the capsule, being attached to it only by its afferent and efferent ves- 

 sel ; and is divided into as many lobes as there are primary subdivi- 

 sions of the afferent vessel ; and every vessel composing it is bare and 

 uncovered, an arrangement of which the economy presents no other 

 example. The efferent vessels, on leaving the Malpighian bodies, 

 enter separately the plexus of capillaries surrounding the uriniferous 

 tubes, and supply that plexus with blood. The blood of the vasa 

 vasorum also probably enters this plexus. The plexus itself lies on 

 the outside of the tubes, on the deep surface of the membrane which 

 furnishes the secretion ; and from it the renal vein arises by nume- 

 rous radicles. 



Thus the blood, in its course through the kidney, passes through 

 two distinct systems of capillary vessels ; first, through that within 

 the extremities of the uriniferous tubes ; and secondly, through that 

 on the exterior of these tubes. The author points out striking dif- 

 ferences between these two systems. He also describes collectively 



