440 



])r. A. l>. Wall,-.-. 



OO3 volt). Their magnitude and duration increase with increased 

 strength of excitation. 



Summation of stimuli, summation of effects, staircase increase, and 

 fatigue decline are manifested by Maze currents. Stimulation of 

 excessive strength abolishes them completely, hut only temporarily. 



The energy of a blaze effect may considerably exceed the energy of 

 its exciting cause. The effects are observable for at least five day- 

 after excision of the eyeball ; they appear to be diminished under pro- 

 longed illumination, and increased under prolonged darkness. 



Fio. 1. 



o-oot 



voU. 



Excitation. 

 Polarisation. 



" Blaze." 



mm. 



Positive response to a single induction shock sent through the ejeball in the 

 positive (upward) direction. 



The influence of raised temperature and increased pressure is studied, 

 and under the influence of the latter four types of response are 

 recorded. 



Comparison is made between blaze currents and the responses of 

 electrical organs as described by du Bois Keymond. 



During and after maximal blaze the resistance diminishes: the 

 diminution is not irreciprocal. 



If single electrical currents are passed through a normal eyeball and 

 a galvanometer, in a " homodrome " and in a " heterodrome " direction 

 (i.e., with and against the direction of normal discharge), the homo- 

 drome (positive) deflection is greater than the heterodrome (negative) 

 deflection. This inequality is the result of positive blaze current, and 

 is abolished by death or strong totalisation. In the latter case the 

 al)olition is temporary. 



The normal electrical response to light persists undiminished at ;<. 

 time when blaze currents have been abolished by tetanisation. On the 

 other hand, blaze current may be present in an eyeball giving n<> 

 response to light. The altered state of the eyeball in relation to light 

 does not necessarily run pa-allel with its altered state in relation to 

 electrical stimuli. 



