CH. XXX VI.] 



THE KIDNEY TUBULES 



537 



functional tubule, which joins a straight or collecting tubule. This 

 passes straight through the medulla, where it joins with others to 



FIG. 414. A diagram of the uriniferous tubes. A, cortex limited externally by the capsule ; 

 a, subcapsular layer not containing Malpighian corpuscles ; a', inner stratum of cortex, also without 

 Malpighian capsules ; B, boundary layer; C, medullary part next the boundary layer; 1, Bowman's 

 capsule of Malpighian corpuscle ; 2, neck of capsule; 3, first convoluted tubule; 4, spiral tubule; 

 5, descending limb of Henle's loop ; 6, the loop proper ; 7, thick part of the ascending limb ; 8, spiral 

 part of ascending limb ; 9, narrow ascending limb in the medullary ray ; 10, the zigzag tubule ; 11, 

 the second convoluted tubule ; 12, the junctional tubule ; 13, the collecting tubule of the medullary 

 ray ; 14, the collecting tube of the boundary layer ; 15, duct of Bellini. (Klein.) 



form one of the ducts of Bellini that open at the apex of the pyramid. 

 These parts are all shown in fig. 414. 



