G. Carl Hnber 



53 



deeper clown in the jjarenchyma of the kidney, as this increases in size ; 

 the tubules showing the greatest development are therefore formed nearest 

 the pelvis of the developing kidney. To show the relative size and the 

 shapes of uriniferous tubules and tubular anlagen developing from differ- 

 ent generations of renal vesicles as also the relative size, shape and extent 

 of branching of collecting tubules and their relation to the former, for a 

 developing kidney of which the most fully developed tubules present 

 about the size and shape of those shown in J of Fig. -i, and H of Fig. 6, 



rv 



Fig. 9. A model of a large or primary collecting tubule, cut just above its 

 origin from the pelvis of the kidney with the collecting tubules resulting 

 from four successive dichotomous divisions, with three renal vesicles, five 

 tubular anlagen in the S-shaped stage and two uriniferous tubules in early 

 stages of development; from the kidney of a human embryo (No. 7), measur- 

 ing o cm. in length. X 133. rv, renal vesicles. 



these representing the oldest stages thus far discussed, I have inserted 

 Figs. 9 and 10. In each of these figures is reproduced a model of a 

 primary collecting duct, beginning with a region a little above its place 

 of origin from the pelvis of the kidney and showing the successive divisions 

 of the same to the ampullar enlargements of the end branches, together 

 with the renal vesicles, tubular anlagen and uriniferous tubules which had 

 developed therewith. Fig. 9 represents these structures as observed in a 

 human embryo 3 cm. in length (embryo No. 7). In this figure, for the 

 sake of clearness, only a part of the .model is reproduced. The cut 



