198 



EXCRETION BY THE KIDNEYS AND SKIN 



FIG. 58. A diagram of the sections of uriniferous tubes. 



A, cortex limited externally by the capsule; a, subcapsular layer not containing 

 Malpighian corpuscles; a', inner stratum of cortex, also without Malpighian cap- 

 sules; B, boundary layer; C, medullary part next the boundary layer; i, Bow- 

 man's capsule of Malpighian corpuscle; 2, neck of capsule; 3, firsfl 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; g, narrow 

 ascending limb in the medullary ray; 10, the zigzag tubule; u, the second con- 

 voluted tubule; 12, the junctional tubule; 13, the collecting tubule of the medul- 

 lary ray; 14, the collecting tube of the boundary layer; 15, duct of Bellini. 

 (Kirkes after Klein.) 



