THE KIDNEY. 133 



(c) Ascending limbs of Henle's loop. (These are small tubes 

 and have already beeu described.) 



(d) The intertubular capillaries. (Inasmuch as, in the speci- 

 imen under consideration, the vessels of the pyramids are mostly in 

 transverse section, they are not readily made out. Especially is this 

 true if the blood-corpuscles have their color discharged.) 



7. Elements of the medullary portion. Fig. 90. 

 (a) Collecting tubes. (These tubes constitute a large proportion 

 of the medulla of the organ. They have been already described. As 



PIG. 91. TRANSVERSE SECTION OF PYRAMID OF MALPIGHII. SAME TISSUE AS SHOWN IN FIG. 88. 

 Stainad with Haema. and Eosin . x 400. 



A. Group of intertubular blood-vessels. 



B. Collecting straight tubules. 



C. Descending limb of Henle's loop. 



D. Ascending limb of Henle's loop. 



E. Principal collecting tubule. 



F. Principal tubule. Lower portion near the papillary duct. 



The ring of cells will be seen detached from the membrana propria in some instances. This is 

 due to contraction of the tissue during the hardening. 



the apex of the Malpighian pyramid is approached, and the straight 

 unite to form the principal collecting tubes, these again uniting to 



