510 



I hope to show in my next paper how important has been the 

 influence of the process of segmentation and the dorsal shifting of 

 the tubule openings, in modifying the anterior kidney tubules and 

 glomus: it is more than probable that many workers on the develop- 



Fig. XV. 



Fig. XIV. Transverse section through a Chrysemys embryo with 18 proto- 

 vertebrae. On the left side of the figure is segment XI right side, middle region ; 

 on the right side of figure is segment XI left side posterior region. Lettering as 

 in Fig. XI. 



Fig. XV. Transverse section of Chrysemys embryo with 18 protoveitebrae. 

 On left side of figure is shown segment XVIII right side, posterior region ; on right 

 side of figure the section passes immediately behind segment XVIII left side. Lettering 

 as iu Fig. XI. 



ment of the kidney have been misled in their observations by not 

 paying enough attention to these factors in the early ontogeny of 

 the urinary organs of Vertebrates. 

 Cardiff, May 20th, 1912. 



