Absorption of Stimulus Energy 89 



were made, the intact remains of non-myelinated terminal in 

 connection with the myeUnated axon were always capable of giving 

 detectable generator potentials upon mechanical stimulation. 

 This suggests that the generator potential arises at membrane 

 parts which are able to function independently of each other; and 

 that these parts are scattered all over the non-myelinated nerve- 

 ending.' 



Fig. 39. Records illustrating the independent nature of different regions 

 of the receptive membrane in a Pacinian corpuscle. The integrity of the 

 entire nerve-ending is not necessary for a receptor potential to be evoked; 

 destruction (b-e) of varying amounts of receptive membrane abolishes 

 only proportional percentages of receptor potential amplitude. Arrows 

 indicate regions of application of the mechanical stimulus in each case. 

 (From Loewenstein and Rathkamp.'^) 



The concept of independent multiple receptor sites has also 

 been applied to the chemoreceptor membrane and is implicit 

 in a theoretical treatment of this phenomenon developed by 

 Beidler^^ in 1954. In attempting to explain some data obtained 

 from mammalian taste cells, Beidler assumed that these cells, like 

 proteins, bind salts at specific loci on their membrane structure. 

 He further assumed that the binding reaction obeys the mass 

 law, and that, being in thermodynamic equilibrium, it is in- 

 dependent of time. From these assumptions, the reaction of a 

 S.O.— G 



