XI 



ELECTRICAL FISHES 



439 



length of intrapolar tract, and the latent period may, with 

 40-50 mm., be prolonged 0'0055-0'004 sec. With shorter 

 interpolar tracts there is usually an " introductory apex," its 

 latency of discharge with descending currents being sometimes 

 0, sometimes, however, of measurable proportions. This Schon- 

 lein refers to the diminution, not merely of rate of conductivity, 

 but also of intensity of excitation, due to anelectrotonic inhibition 

 at the anode during each single impact of current (O'OOl" dura- 



Fir,. 278. Excitation of one organ-preparation by discharge from another, through the nerve. 



(Gotch.) 



tion). We should anticipate that the discharge of an organ- 

 preparation provoked by excitation of the nerve would be sufficient 

 to excite directly a second preparation in the same circuit. 

 The accompanying schemata (Fig. 278) show that there must 

 then be either summation or subtraction of the galvanometer 

 effect. That this is actually the case has been proved by Gotch 

 with the spring -rheotorne. The alteration (augmentation or 

 diminution) of the galvanometer effect caused by the discharge 

 of the nerve-organ preparation appears regularly about O'Ol" 

 after the maximum of the discharge. One then asks whether 



