GLANDS. 433 



between this and the framework of elastic tissue already de- 

 scribed. Analogy, therefore, is entirely opposed to the de- 

 scription of the author of the paper in the Philosophical 

 Transactions to which reference has been made more than 

 once. 



In the second place, Mr. Bowman describes the renal artery 

 as being spent upon the Malpighian bodies, with the excep- 

 tion of a few branches given off to the coats of the excretory 

 ducts and of the larger vessels; while, according to the 

 Author's observations, only a proportion of the branches of 

 the renal artery are thus disposed of. 



The accuracy of the foregoing account of the distribution 

 of the blood-vessels of the kidney is borne out, to a very great 

 extent, by the results furnished by injection. 



1st. The Malpighian plexus can be injected with great 

 facility by the artery, but not by the vein : the reason of this 

 will be obvious on a little reflection ; the branches of the 

 renal artery pass directly to the Malpighian plexus ; those of 

 the renal vein, commencing from the larger or terminal trunks, 

 end either in the plexus surrounding the tubes of the kidney, 

 or in that which lies on its surface between the convolutions 

 of those tubes ; and it is in one or other plexus that the 

 efferent or portal vein of the Malpighian tuft terminates ; so 

 that between the terminal branches of the renal vein and the 

 origin of the efferent vessel, a complicated plexus is inter- 

 posed that surrounding the uriniferous tubes ; the injection, 

 therefore, before reaching the Malpighian tuft, would have to 

 traverse the plexus already spoken of; and it is this which 

 accounts for its being so difficult, if not impossible, to inject 

 the Malpighian plexus from the renal vein. 



2nd. The plexus surrounding the tubes may be injected 

 with care, from both the artery and vein ; but especially from 

 the latter. 



3rd. The plexus, ramifying between the loops of the tubes 

 on the surface of the kidney, may also be readily injected 

 from either artery or vein. 



Occasionally, the injection will pass from the blood-vessels, 

 and escape into the tubes, or their Malpighian extremities. 



M !M 2 



