THIS paper is concerned with the rate of regeneration of sensory fibers, calculated on the basis of the rate of advance of Tinel's sign, during the recovery of injured peripheral nerves. Though it is generally accepted that the eliciting of Tinel's sign is evidence of the presence of "young axis-cylinders in the process of regeneration," there has been no histologic confirmation of the structure of the fiber at the site of percussion. The present account is not concerned either with the morphologic features of the recovering nerve fiber or with the prognostic significance of the sign, but is confined to a consideration of the rate at which it advances.
With the exception of Seddon, Medawar and Smith,1 those who have devoted attention to the estimation of rates of recovery on this basis have omitted to indicate whether, in any instance, this was obtained by a single calculation or from