It has been previously established that a fraction of the homogenate of cephalic regions of Eisenia foetida Sav. (fraction A) is responsible for the maintenance of the turgidity of the clitellum and for the inhibition of cephalic regeneration. This fraction was tested on associations of testes and ovaries maintained in organ culture and was shown to have an action comparable to that of cerebroid ganglia in that it stimulates the secretion of testicular androgen. This preliminary result suggests that development of the clitellum, inhibition of cephalic regeneration, and secretion of testicular androgen are controlled by a single substance.