444 THE KIDNEYS AND THEIR SECRETION, 

 larger than this immediately before they open through the 



On tracing these tu- 

 bules upwards from the papillae, 

 they are found to divide dicho- 

 tomously as they ascend through 

 the pyramids, and on reaching 

 the bases of the latter, they 

 begin to branch and diverge 

 more widely, and to form by 

 their branches and convolutions 

 the essential part of the cortical 

 portion of the organ. At their 

 extremities they become dilated 

 into the MalpigJiian capsules. 

 Until very recently, it has been 

 believed that the straight tu- 

 bules in the pyramids branch 

 out and become convoluted im- 

 mediately on reaching the bases 

 of the pyramids ; but it is now 

 commonly believed that between 

 the straight tubes in the pyra- 

 mids and the convoluted tubes 

 in the cortical portion, "there is 

 a system of tubules of smaller diameter than either, which 

 form inter- communications between the two varieties for- 

 merly recognised. These intervening tubules, called the 

 looped tubes of Henle, arising from the straight tubes in 



* Fig. 115. Diagram of the looped uriniferous tubes and their con- 

 nection with the capsules of the glomeruli (from Southey, after Ludwig). 

 In the lower part of the figure one of the large branching tubes is shown 

 opening on a papilla ; in the middle part two of the looped small tubes 

 are seen descending to form their loops, and re-ascending in the medul- 

 lary substance ; while in the upper or cortical part, these tubes, after 

 some enlargement, are represented as becoming convoluted and dilated 

 in the capsules of glomeruli. 



