232 ELEMENTARY PHYSIOLOGY. [XXII. 



the individual cells may or may not 

 be distinct, they have each a spherical 

 nucleus and are striated in their outer 

 portions. Sometimes the lumen is large, 

 sometimes it can scarcely be made out. 



e. The continuation outwards in the me- 

 dullary rays of the ascending loop of 

 Henle. 



f. In the outer half of the cortex are deeply 

 stained short tubules running out from 

 the rays and sometimes seen to be con- 

 tinuous with the ascending loops of 

 Henle ; their cells resemble those of the 

 ascending loop except that they are of 

 unequal size, thus giving a very zigzag 

 outline to the tubule ; this is the ' ir- 

 regular ' portion of the urinary tubule. 



f). In the medullary rays will also be seen 

 one or two rather large tubes with con- 

 spicuous spherical nuclei, these are the 

 so-called spiral tubules. Note also in 

 the rays the smaller straight (collecting) 

 tubes. 



A basement membrane may be made out in 

 all portions of the urinary tubule. 



4. Cut sections at right angles to the medullary 

 rays through the lower part of the cortex and 

 observe the medullary rays surrounded by con- 

 voluted tubes. 



