90 T. H. BuRLEND, Tlie pronephros of Chryserriys marginata. 



Fig. 50. (Section 5,26.) Notice a mesonephric tubule cut across 

 on the right side of the figure. It is in connection with both duct and 

 nephrotome. 



Fig. 51. (Section 5,27.) In this section (the succeeding one to 

 that shown in Fig. 50 a nephrotome and nephrostome are shown on each 

 side : the nephrotome on the left side is imperfectly closed. 



Fig. 52. (Section 5,28.) This section succeeds the one shown in 

 Fig. 51. 



Fig. 53. (Section 8,27.) A section through the region of segment 

 XXIV in Embryo M. The relations of protovertebra, nephrotome, lateral 

 plate mesoderm and pronephric duct to one another are shown ; also the 

 absence of any close relation between ectoderm and duct in this region 

 of the body. 



