SECRETION. 



435 



Fig. 163. Diagram of the Course of Two Uriniferous Tubules. 

 (LANDOIS.) 



1, Malpighian tuft surrounded by Bowman's capsule. 2, Constriction on 

 neck. 3, Proximal convoluted tubule. 4, Spiral tubule. 5, Descending limb 

 of Henle's loop-tube. 6, Henle's loop. 9, Wavy part of ascending limb. 10, 

 Irregular tubule. 11, Distal convoluted tubule. 12, First part of collecting 

 tube. 13, Straight part of collecting tube. A, Cortex. B t Boundary zone. C, 

 Papillary zone. 



of smaller size, and these immediately subdivide into from eight to 

 twelve infundibula, or calyces, from their resemblance to cups. Into 

 each calyx there projects the point or extremity of a renal pyramid. 

 The blood-vessels lie within the sinus, between its wall and the exte- 



