XXII.] STRUCTURE OF THE KIDNEY. 231 



sometimes imbricated, with striated outer 

 portions and containing oval nuclei ; the 

 lumen is small. 



. The descending limbs of the loops; 

 these are much narrower, with trans- 

 parent flattened epithelium the nuclei 

 of which project into the lumen, some- 

 times alternately on the two sides, and 

 thus the tube, except for its basement 

 membrane, simulates a blood capillary. 



The change in character of the epithelium 

 may take place either in the ascending or in 

 the descending limb of the loop. 



e. The numerous blood-vessels between the 

 medullary rays (cp. 8, b) ; in the outer 

 part of the layer rather large arteries 

 and veins cut transversely or obliquely 

 will be seen (cp. 1, c). 



c. In the cortex 



a. The end- capsules, with the nuclei of 

 their epithelium. 



/9. The glomerulus in each end-capsule 

 (cp. 8, c) and the nuclei of its capillaries. 



7. The narrow neck of the capsule, this 

 will be obvious in those capsules only 

 in which the section has passed longi- 

 tudinally through the neck. 



8. The coiled course of the convoluted 

 tubes (tubuli contorti); the outlines of 



