Tlie pronephros of Chryseinys margiiiata. 



41 



Embryo 0. 



Chrijsemijs marginata removed from blastoderm. Stained with 

 Ehelich's Haematoxylin for 72 hours and mounted on 8 slides 

 having respectively 58, 60, 60, 75, 65, 52, 52 and 48 sections. Owing- 

 to the flexure of the body it is practically impossible to determine 

 the body-seg'ments in which the individual pronephric tubules occur, 

 but I have attempted to do this by reference to the position of the 

 pronephric tubules in younger embrj^'os. 



I made a diagrammatic representation of the front end of the 

 kidney on each side, although in this there was no attempt made to 

 show the relative length and breadth of the tubules, but merely to 

 determine their relations to each other: since the region of each 



tubules 



nephro- 

 stomes 



pro- 



uephric 



duct 



Textfig. A. 



Diagram of the anterior end of the left kidney 

 (pronephric portion) in Embryo 0. 



Textfig. B. 



Diagram of the anterior end of 

 the right kidney in Embryo 0. 



