428 COMPARATIVE ELECTRO-PHYSIOLOGY 



followed by an after-oscillation. The essential similarities 

 between these and corresponding records obtained on a fast- 

 moving drum, of the response of the petiole of Bryophyllum 

 under light (fig. 253), are sufficiently obvious. 



When the excitability of the tissue is not so high, we 

 may obtain after-effects of Type II., in which the formula is 



( | ) or ( ). This was exemplified in vegetable 



tissues (cf. fig. 245 d}. In Ophiocephalus, I was able to obtain 

 this result also, when the specimen was slightly fatigued 

 (fig. 256). With the eye of the frog, Kuhne and Steiner 

 obtained the record given in fig. 257, which is seen to be 

 parallel to that given in fig. 256, its true significance being 



shown in the formula ( I ). 



FIG. 256. FIG. 257. 



FlGS. 256, 257. Parallel Records given by Plant and Eye, during and 

 after Illumination, as illustrative of Intermediate Type II. ( h ) 



Fig. 256. Response of retina of Ophiocephalns when slightly 



fatigued. 

 Fig. 257. Response of frog's eye (Kiihne and Steiner). 



A sub-case of Type II. is represented again, by ( ), 



where on the sudden cessation of light, there is a transient 

 increase of excitatory response. This, as we saw, was due to 

 the abrupt withdrawal of the antagonistic influence of a 

 reversing force. I may state here that I have been able to 

 demonstrate an exactly parallel effect with nerve of frog, 

 where the excitatory negative effect during stimulus under- 

 goes a brief and sudden augmentation on its cessation (p. 536). 

 This sudden augmentation on the stoppage of stimulus has 

 been taken as a proof of the existence of antagonistic pro- 

 cesses of assimilation and dissimilation, rather than as due to 

 molecular derangement by external stimulus and its after-effect. 



