[The peptide nature of the factor inhibiting cephalic regeneration in Eisenia foetida Sav. f. typica (Annelida, Oligocheta)].

The active material incubated with trypsin, or pronase lost its activity but not with pepsin. The peptide nature of the inhibitory factor is thus determined. Dialysis and gel filtration chromatography of this substance suggest that the inhibitory factor is a small molecule.