1904.] the Cat's Foot studied by the Electrometer. 



98. 



5. A series to exhibit the relation between magnitude of stimulation 



and magnitude of response. 



6. A single response before and after tetanus to illustrate " facilita- 



tion " (Bahnung). 



7. A single response before and after tetanus to illustrate fatigue. 



8. A series to illustrate summation of stimuli. 



9. A series to show the difference between infrequent and frequent 



stimuli. . 



No special comment upon the records appears to be necessary, 

 beyond, perhaps, a remark to the effect that " summation of stimuli," 

 as distinguished from " summation of effects," is, by reason of the 

 great length of the latent period, a particularly evident phenomenon. 

 The latent period itself has its seat at the organ of intermediation 

 between nerve and secreting cell, as is shown by the absence of 

 demonstrable lost time to direct excitation and along the nerve itself. 

 The declining excitability of the secreto-motor nerve fibres is very 

 evidently in the centrifugal direction, stimulation of the nerve nearer 

 to the periphery being effective after stimulation further from the. 

 periphery has ceased to be effective. 



Similar effects are obtainable on nerve-skin preparations of the frog, 

 " summation of stimuli " and " staircase effect " being, as in the case of 

 the cat, particularly evident. 



O-OL- 



o 5 io 15 sees. 



Fig. 1. — Cat. Nerve-skin response to a single induction shock 40 minutes 

 post-mortem. 



