[Regeneration of the reproductive system and differentiation of extra-gonadic germ cells inEisenia foetida Sav.].

The regeneration of the reproductive system from the body wall reduced to its parietal mesoderm covered with epidermis has been studied in adult worms. It has enabled us to show that each reproductive organ can normally become differentiated independently of the others, from determined territories in the older parietal mesoderm.An extra-gonadic germ line is liable to be formed in the coelomic layers, particularly in the ventral region of the genital segments. This line may become differentiated as male but not as female.The extra-gonadic germ elements appearing in the female territory are incapable of complete self-differentiation.