442 THE KIDXEYS AND THEIR SECRETIOX. 



larger than this immediately before they open through the 

 Fig. 122* papilla. On tracing these tu- 



bules upwards from the papillae, 

 they are found to divide dicho- 

 tomotisly 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 Malpighian capsules. 

 Until recently, it was believed 

 that the straight tubules in the 

 pyramids branch out and be- 

 come convoluted immediately on 

 reaching the bases of the pyra- 

 mids ; but between the straight 

 tubes in the pyramids and the 

 convoluted tubes in the cortical 

 portion, there has been shown to 

 be a system of tubules of smaller diameter than either, 

 which form intercommunications between the two varieties 

 formerly recognised. These intervening tubules, called the 

 looped tubes of Henle, arising from the straight tubes in 



* Fig. 122. Diagram of the looped uriniferous tubes and their con- 

 nection with the capsules of the glomeruli (from Sou they, 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 an ilated 

 in the capsules of glomeruli. 



