CHEMO-TROPISM AND GALVANO-TROPISM 



555 



present case, however, no complicating differential action 

 being involved, and the magnification being considerable, we 

 are able to detect a make-effect, which is contrary to the 

 break-effect at anode — that is to say, it induces an expan- 

 sion and consequent convexity. This anode-make expan- 

 sion is quick, and soon reaches its maximum. At break the 

 usual contractile effect is induced, 

 but this is not here very clearly dis- 

 tinguishable from the movement of 

 a natural recovery (fig. 230). 



The current was now reversed, 

 making the upper half of the pulvinus 

 kathode. This induced a contraction 

 and concavity which, unlike the 

 quickly exhausted effect of the 

 anode-make, went on increasing for 

 some time. At kathode-break we 

 see not only the cessation of the 

 contractile effect, but probably also 

 an expansion, aided by the natural 

 process of recovery. Other experi- 

 ments will be described presently, 

 which will clearly show that not 

 only do anode and kathode induce 

 opposite effects, but that each at its 

 own make and break exhibits re- 

 actions, which, though not of equal 

 intensity, are of contrary signs. 

 These interesting opposite effects, 

 at make and break respectively, 

 are not easily observed in muscle under ordinary condi- 

 tions, inasmuch as muscle which is in the usual state 

 of expansion cannot be further expanded ; but Bieder- 

 mann has found that smooth or cross-striated muscles, 

 which are partially contracted, exhibit local expansion at the 

 anode-make. Again, he found in the case of cardiac muscle 

 that the kathode-break also gave rise to local expansion. 



Fig. 230. Polar Effects 01 

 Currents due to Localised 

 Application on Upper Half 

 of Pulvinus of Erytkrina 

 indica 



Up curve, in this and in fig. 

 232, represents expansion 

 and convexity. Down 

 curve represents contrac- 

 tion and concavity. Con- 

 tinuous curve represents 

 the action at make. The 

 dotted curve shows the 

 effect at break. Am - con- 

 vexity induced at anode- 

 make. a/> = responsive con- 

 cavity at anode-break. 

 k/ji = induced concavity at 

 kathode-make. K.6 = ex- 

 pansion induced at kathode- 

 break. The time-marks in 

 this and following curves 

 represent minutes. 



