§2] EFFECT ON STRUCTURE AND FUNCTIONS 129 



§ 2. The Effect op Electricity upon the Structttee 

 AND General Functions of Protoplasm 



The fundamental phenomenon of the action of an electric 

 current upon protoplasm may be seen while watching a helio- 

 zoan (Actinospheerium), lying in a drop of water, through 

 which a weak, constant current is "made." We find that the 

 filamentous pseudopodia begin quickly to retract at the two 

 poles lying in the axis of the current ; and as the current 

 continues, this contraction continues likewise. The primary 

 effect of a weak constant current is thus a centripetal flowing 

 of the protoplasm. The current stimulates to contraction. 



If, now, the current be increased, or be longer continued, 

 further changes occur. The pseudopodia lying in the current 

 become varicose, and break up into a chain of drops; the 

 vacuoles on the periphery begin to burst, emptying out their 

 fluids; and in these regions the protoplasm collapses. Thus, 

 the stronger current produces continued contraction, accom- 

 panied by collapse of the protoplasmic foam-work. 



Finally, the plasma itself begins, upon the anode side, to dis- 

 integrate, and the loose particles to move towards the positive 

 electrode. As the plasma of this side is gradually eaten away, 

 the outline of the Actinosphserium passes through phases like 

 those of the waning moon, untU, finally, the last thin crescent 

 fades away. The particles of the mass have wholly lost their 

 cohesion (Fig. 28). 



The facts just given concerning the behavior of Actino- 

 sphserium to the constant current are gathered frOm the observa- 

 tions of KtJHNE ('64, p. 59) and Verworn ('89', pp. 8, 9). 

 Fundamentally similar observations have been made by KiJHNE 

 ('64, p. 79) and Verworn ('89^ p. 274) on Myxomycetes, 

 and by Verworn ('89% pp. 13, 17) on the rhizopods, Poly- 

 stomella and Pelomyxa. So these data may be considered as 

 of general worth for naked protoplasm. 



Also upon ciliated epithelium, the constant current acts 

 as a very strong excitant, producing an active movement in 

 cilia which had previously nearly ceased to beat. This excita- 

 tion occurs, especially about the two poles, immediately upon 

 "making" the current. (Kraft, '90, pp. 234, 235.) 



