386 



COMPARATIVE ELECTRO-PHYSIOLOGY 



of which shows the curve of over-balance. Stimulus of hah 

 a minute's duration was now applied, and it will be noticed 



that on account of the re- 

 sponsive acceleration the 

 slope becomes increasingly 

 diminished, till, after an 

 interval of one minute and 

 a half, the curve becomes 

 horizontal. After this it is 

 reversed to the upward direc- 

 tion. It will thus be seen 

 that the responsive accelera- 

 tion has here, induced a rate 

 of suction which is not merely 

 sufficient to compensate the 

 over-balance, but greatly ex- 

 ceeds it. In the next photo- 

 graphic record (fig. 231) I have been successful in showing 

 the immediate and persistent after-effects. In order to do 



|Fic. 230. Suctional Response 

 under Over-balance 



Stimulus of 30 seconds neutralises 

 over-balance and reverses curve. 



FlG. 231. Photographic Record of Effect of Stimulus on Over-balance 



First stimulus for 2 seconds, represented by first vertical line, neutralises 

 and reverses over-balance. Horizontal record after reversal represents 

 persistent after-effect. Second stimulus for 2 seconds, represented 

 by second vertical line, gives rise|to up-record, the persistent after- 

 effect being represented by a curve_of diminished slope. 



this within the limited range of a photographic plate, I 

 employed stimulus of the short duration of two seconds. 



