“…An early system-analytic study of the crayfish stretch-receptor by Borsellino, Poppele, and Terzuolo [7] has led to a comparative study by Fohlmeister, Poppele and Purple [16,17] of nerve-impulse generating transducers. The linear frequency response of the lateral eye of the horseshoe crab Limulus was given early investigation by Pinter [40], by Biederman-Thorson and Thorson [5,52], and by Dodge, Knight and Toyoda [14,26,43], Over the past decade a very detailed and predictively accurate linear system-analytic model has evolved for the visual neurophysiology of Limulus [8,9,44], There now have been a substantial number of experimental forays unto applying methods of nonlinear system identification, in the general spirit of Wiener's proposal, to biological transducers [15, 19, 20, 28, 30, 32, 33, 35-37, 45, 46, 53, 55, 57], Concurrently, the theoretical state of the subject has continued to advance. It was recognized before 1963 by Barrett [2] that Wiener's white-noise approach is just one member of a wide class of analytic procedures, each based on its own particular ensemble of input test signals.…”