SIXTEEN FIGUEESThe denervated limb of the adult newt cannot regenerate when amputated whereas the innervated one can, provided that the number of fibers at the amputation surface exceed one-third to one-half of the normal nerve supply (Singer, '42-'52). These threshold needs may be satisfied by various combine tions of mixed motor and sensory fibers. The present work shows that the neuronal dependence of the regenerative process does not require a normal relation between the regenerate and the peripheral nerve processes ; and that all parts of the neuron and not just the peripheral process are effective as agents of growth. Moreover the study shows that a pool of neurons embedded in the regenerate itself can sustain the growth in the absence of other nerve connections. To demonstrate this the spinal nerves supplying the regenerating limb were interrupted and then the spinal ganglia removed and implanted directly into the growth itself (Ashbaugh and Singer, '57, preliminary report).