THE KIDNEYS. 



389 



of the kidney, except the straight tubes of Bellini in the 

 pyramids. 



The curved or collecting tubule terminates in the 

 distal convoluted tubule, this in the irregular tubule 

 which leads into the loop of Henle, a contracted portion 

 of the tubule, and which terminates in the spiral tubule. 

 The spiral tubule terminates in the proximal convoluted 

 tubule, which becomes contracted and then expands, form- 

 ing the capsule of the Malpighian corpuscle. The 



FIG. 170. THE SECRETING PORTIONS OF THE KIDNEY. 



II, Bowman's capsule and glomerulns ; a, vas afferens : e. vas efferens : c. capillary net- 

 work of the cortex : k, endothelium of the capsule : h. origin of a convoluted tubule : III, 

 "rodded" cells from a convoluted tubule: 2, seen from the side, with. K, inner granular 

 lone : 1, from the surface ; IV, cells lining Henle's loop ; V, cells of a collecting tube ; VI, 

 section of an excretory tube. 



straight tubuli are lined with columnar epithelium 

 throughout ; the convoluted tubuli, up to the corpuscle, 

 present a varied epithelium ; in general, it may be said 

 to be of the glandular type. The epithelium rests on a 

 basement membrane, which is supported by a delicate 

 fibrous coat. 



The cortical substance dips down between the pyra- 

 mids, forming the columns of Bertin. A single tubule 

 becomes so multiplied by repeated divisions as to form a 

 cone or pyramid, and the pyramids of Malpighi may be 



