STIMULI AND THEIR ACTIONS 



417 



continues as long as the current remains. This latter is expressed in a 

 constant advance of the phenomena of contraction. The protoplasm 

 constantly draws back from the anode toward the body, and soon 

 the pseudopodia are wholly drawn in. Then the contraction is 

 noticed upon the body itself: the protoplasm of the walls of the 

 vacuoles retracts more and more toward the interior, the vacuoles 

 collapse, and the protoplasm itself disintegrates partly into its 

 granules. This process of amalgamation and disintegration con- 

 tinues as long as the current flows, but gradually decreases in m- 

 tensity. Hence there can be no doubt that the constant current 

 stimulates throughout its duration. At the moment whenUhe 





Fig. 198. — AcUnoapluiirmui Eichhomil in four successive stages of polar excitation by tlie constant 

 current. The protoplasm is disintegrating from the side of the anode. 



current is broken the amalgamation-process at the anode ceases at 

 once. A few phenomena of stimulation are noticeable at the kathode, 

 the pseudopodia again showing contraction-phenomena and their 

 protoplasm flowing together into globules and spindles. But this 

 effect gradually ceases and there is no complete retraction of the 

 kathodic pseudopodia. If the current be not broken, the body of 

 the Adinosphceriutn disintegrates from the anode constantly, but 

 in the course of time more slowly, until finally, if the current is 

 feeble, the process wholly ceases. If, however, the current is 

 stronger, the disintegration proceeds rapidly until the whole body 

 has fallen into a lifeless mass of granules. Hence, Actinosphcerium 

 is stimulated to crmtradion hy the im thing of the constant current at 

 both the anode and the kcdhcdc, ly the hrcahiroy only cd the kathode. 



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