STRUCTURE OF THE KIDNEY. 447 



although exceedingly thin, is present, and has delineated 

 the appearance in the accompanying diagram (fig. 118). 



Besides the small afferent arteries of the Malpighian 

 bodies, there are, of course, Fig. 118.* 



others which are distri- 

 buted in the ordinary 

 manner, for nutrition's 

 sake, to the different parts 

 of the organ ; and in the 

 pyramids, between the 

 tubes, there are numerous 

 straight vessels, the vasa 

 recta, the origin of which 

 is somewhat uncertain, 

 some observers supposing 

 them to be branches of 

 vasa efferentia from Mal- 

 pighian bodies, and therefore comparable to the venous 

 plexus around the tubules in the cortical portion, while 

 others think that they arise directly from small branches 

 of the renal arteries. 



Between the tubes, vessels, etc., which make up the 

 main substance of the kidney, there exists in small quantity 

 a fine matrix of areolar tissue. 



The nerves of the kidney are derived from the renal 

 plexus, f 



* Fig. 1 1 8. Semidiagrammatic representation of a Malpighian body 

 in its relation to the iiriniferous tube (from Kolliker) ~. a, capsule 

 of the Malpighian body ; d, epithelium of the uriniferous tube ; e, de- 

 tached epithelium ; /, afferent vessel ; g, efferent vessel ; h, convoluted 

 vessels of the glomerulus. 



f For a more detailed account of the structure of the kidney and a 

 summary of the various opinions on the subject, the student may be 

 referred especially to Quain's Anatomy, 7th ed., and to a paper by Dr. 

 Reginald Southey in vol. i. of the St. Bartholomew's Hospital Reports. 



