284 



J. B. Haycraft, 



and collecting tubules, as in the case of the Wolffian tubules 

 and Wolffian duct, a communication between them being- only subse- 

 quently established." 



The Balfour and Sedgwick vie^w is questioned. 



When however we turn to the original paper of Sedgwick we 

 shall see that his facts and the statements given by him do not tally 



with Balfour's own writings on the subject. 

 It appears that Sedgwick undertook the 

 investigation at Balfour's suggestion and 

 that Balfour himself verified Sedgwick's 

 conclusions by a study of Sedgwick's spe- 

 cimens, and based his conclusions on Sedg- 

 wick's work. In his paper i) "we find that 

 the walls of the tubules arise from the 

 cells of the blastema; the lumen, however, 

 not as in the anterior part (mesonephros) 

 first appearing as an independent cavity, 

 which opens later into the duct, but being 

 from the first continuous with the lumen 

 of the ureter." The growing tubules are 

 carefully figiu-ed by Sedgwick (PI. I. Fig. 1) 

 and one can see the cavity of the bran- 

 ched ureter lined by epithelium surrounded 

 at its extremity and continuous with cells 

 of the blastema disposed around it in a somewhat radiating fashion. 

 There is nothing in the text of Sedgwick's paper nor in the figures 

 that would lead a careful reader to imagine that the collecting tubules 

 push their way towards isolated masses of blastema cells already 

 differentiating themselves into the epithelium of the convoluted tubules. 

 The cells of the blastema supposed to be differentiating tliemselves 

 into epithelium are described and figured as being fi-om the first con- 

 tinuous with the ends of the tubules. Far from intending to attach 



Fig. 1. 



This is a copy of Sedgwick's 

 figure representing what he 

 believed to be the formation of 

 a tubule from blastema cells. 

 The outside cells, really young 

 connective tissue cells, are sup- 

 posed to be passing by inter- 

 mediate stages into the epithe- 

 lium of the tubule. Really 

 the section is not a section 

 through the end of a tubule 

 at all, but an oblique section 

 in its course. 



') A. Sedgwick, Development of the Kidney in its relation to the Wolffian 

 lîody. (^ J. M. Sc. 1880. p. 10.3. 



