EXCITABILITY DETERMINED BY INTERFERENCE 14^7 



of potash was next applied on the right-hand point, and 

 from the record it is seen that the ' up ' part of the di-phasic 

 response, due to the excitation of the right-hand side, was 

 thus completely abolished, the * down ' response being at the 



same time increased by the 

 suppression of this opposing 

 response (fig. 102). 



In order to demonstrate the 

 use of the Diametric Balance 

 Method, I undertook to investi- 

 gate by its means the influence 

 of the lowering of tempera- 

 ture on excitability. For this 



FIG. 1 02. Photographic Records. 

 (a) Di-phasic response of petiole 

 of Bryophylhuii) the up compo- 

 nent being due to the excitation 

 of right side. Strong application 

 of KHO on the right abolished 

 this responsive component, giving 

 rise in (b) to enhanced down 

 response 



FIG. 103. Photographic Record of 

 Response of Petiole of Cauliflower 

 by the Diametric Method 



A contact was naturally more excitable, 

 hence resultant ' up '-response. Ex- 

 citability of A being depressed by 

 local application of ice, the re- 

 sultant response became converted 

 to ' down ' ; normal ' up '-response 

 was restored on allowing the tissue 

 to return to surrounding temperature. 



purpose, I took a petiole of cauliflower. In this instance, 

 the natural excitability of the upper contact, A, was greater 

 than that of the lower, B. Hence the resultant response was 

 not zero, but ' up.' The point A was now cooled locally by 

 ice. This process so lowered its excitability that that of B 

 was now relatively the greater, hence the resultant response 

 was found to be reversed or f down.' The point A was next 



L 2 



