22 T. H. BURLEND, 



a groove to 3,16, and as a solid outgrowth from 3,16 to 3,50. The 

 duct continues from this point backwards until 4,44, when it is no 

 longer visible. 



Thus the region over which the kidney extends on the right 

 side includes: a few post, sections in V, VI, VII, VIII, IX (ant. 

 half) and the duct is present in the post, half of IX, X, XI, XII 

 and 4 sections more posterior. 



Embryo H. 



3^2 luTO- long. Stained in Grenacher's Boraxcarmine for 44^2 

 hours. 



The sections were mounted on 6 slides which had respectively 

 47, 45, 45, 48, 44, 47 sections. 



Body begins 1,8. 

 Left side of embryo Right side of embrj^o 



Heart 2,17—2,42. Neurenteric canal 6,9—6,15. 



Traces of a groove occur on the left side in the somatic laj'er 

 of the mesoderm between 3,20 and 3,30 ; after this the kidney rudi- 

 ment is well marked, and the solid outgrowth extends back to 4,21 ; 

 the duct extends from 4,21 to 5,20. 



(See Plate 1 and 2 Figs. 16, 17, 18, 19 and 20.) 



