G. Carl Huber 63 



the beginning segment of the tubulus contortus of the second order." 

 The descending or proximal arm of Henle's loop to near its end is there- 

 fore, according to Stoerk, lined by an epithelium which is like the epithe- 

 lium which lines the proximal convoluted portion and presents a diameter 

 of tubule and lumen, which is also like the proximal convoluted portion, 

 while the ascending limb, which is of smaller diameter, is lined by cells 

 having a darker protoplasm and this not only in earlier stages of 

 development, but also in later stages and in post-foetal life, as is apparent 

 from his description and also his diagram given in Fig. 27 of his article. 

 To state clearly Stoerk's position, I shall quote from his summary as 

 follows : 



" Das Protoplasma des Kaniilchenepithels. von der Insertionsstelle am aiisseren 

 Blatt der Bowmanschen Kapsel angefacgen bis zur Umbiegungstelle dei- Henleschen 

 Schleife. wird ziemlich gleichzeitig mit dem Auswachsen dei- Schleife hell, das Inmen 

 dieses Kanalchenabschnittes erweitert. Der helle und weitere Schenkel der Henleschen 

 Schleife ist der absteigende und nicht, wie bisher angenommen wurde, der Aufstei- 

 gende." Stoerk also states in discussing his obserTations on this point that " Dieser 

 vollig einwandsfreie und ausnahmslos konstante Befund steht in direktem Gegensatze 

 zu der Darstellung im Schweiger-Seidelschen Schema und, dem seinerzeit Gesagten 

 gemitss, auch im Gegensatze zu dem, was seither zur allgemein giiltigen Anschauung 

 liber das Verhalten der Henleschen Schleife geworden ist. Dass die falsche Lehre 

 bisher keine Richtigstellung erfahren hat, ist um so verwunderlicher, als eine Reihe von 

 allgemein bekannten Beobachtungen so whol der normalen wie der patliologischen His- 

 tologie auf das Wiedersinnige in der Sache hiitten hinweisen konnen." 



I have quoted thus fully from Stoerk, as his observations (based on 

 reconstructions) on the development and structure of the loop of Henle 

 have led him to conclusions which are so at variance with the generally 

 accepted views concerning the structure of the different parts of this 

 portion of the uriniferous tubule that a clear statement of his position 

 seemed necessary and this could best be given by making free use of his 

 own words. That the older and generally accepted view of the size and 

 structure of the descending or proximal limb of Henle's loop — namely 

 that it represents that part of the uriniferous tubule which shows the 

 smallest diameter, as generally given in the diagrams of uriniferous 

 tubules, beginning with the well-known one of Schweiger-Seidel, and that 

 it is lined by a flattened epithelium— is the correct one and that Stoerk is 

 in error when he states that this portion of the uriniferous tubule presents 

 essentially the same diameter as the proximal convoluted tubule and is 

 lined by a similar epithelium, is shown by those of my models whicli 

 show advanced stages in the development of the uriniferous tubules. 

 The source of his error can, I believe, be readily shown. If one may be 

 allowed to judge from his figures, he has reconstructed only relatively 

 early stages in the development of the uriniferous tubules. The tubule 

 shown as model L, as found in his plates, presents the most advanced 

 stage figured by him. Figure 18 shows in very favorable section a tubule 

 of about the stage of development as that shown in model L. Tn the 



