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HANS-JURG MARTHY 



5. The kidneys develop in close relationship to the right and left vena cava. By 

 peripheral accumulation of cell-material the development of the lumina is 

 already foreshadowed. The separated paired kidney-sacs extend widely into 

 the posterior part of the viscéral complex and anterior to the heart. They 

 replace the pericardial cavity as this becomes reduced. The left kidney-sac is 

 better developed than the right. 



6. The reno-pericardial canal of the Decapods is represented by the reno-peri- 

 cardial connection. This differentiates late during the development into an 

 open connection in that the ureter breaks through into the pericardial funnel 

 The pericardial funnel forms the common exit, while the ureter represents a 

 short process of the kidney, which opens into the pericardial funnel across 

 the branchial vein. 



7. Gonad and pericardial glands become recognizable through the development 

 of the pericardial cavity and through the development of the bloodsystem. 

 The first lies on the dorsal side of the ventricle, the latter on the dorsal side 

 of the branchial hearts where they project into the pericardium and finally 

 the pericardial glands develop splits on the side opposit to the point of attach- 

 ment. 



8. The gonoducts appear as ingrowths of ectoderm into the pericardium and 

 unité with a prolifération of coelomic epithelium, grow towards the gonad 

 and develop a lumen. 



9. The " coelom-mesoderm " differentiates specifically in the différent parts of 

 the coelom: 



a) — In the pericardium, as an epithelium poor in nuclei. 



— In the pericardial funnel, as cubic ciliated cells. 



— The coelomic part of secondarily developed gonoducts (stage XVI) re- 

 presents a new differentiation of coelomic epithelium. 



b) In the kidneys, as kidney-sac-epithelium and cells of the venous appendages 



of the kidney, a tall cylindrical epithelium. 



c) In the gonad, as cells with large nuclei poor in chromatine and smaller 



more peripheral nuclei. The first are apparently germ-cells, the second 

 stroma-cells. 



d) In the pericardial glands it remains almost undifferentiated. The tissue is 



loosened by pénétration of the lumina of the branchial hearts. 



