132 



ELECTRICITY AND PROTOPLASM 



[Cn. VI 



tion takes place at both poles, since both are, alternately, 

 anodes (Fig. 30). 



Similar effects have been observed in other cases. Thus, 

 when an amoeba is subjected to an alternating current, it be- 

 comes spherical ; the protoplasmic streaming of the plasmodia 



of a myxomycete ceases, and, 

 with stronger currents, the 

 whole mass contracts, water 

 being forced out.^ Finally, 

 an attempt at a similar re- 

 sult is seen in the stamen- 

 hair cells of Tradescantia, in 

 which, under stimulation, the 

 protoplasmic threads segre- 

 gate into irregular or sphe- 

 roidal clumps. (KtiHNE, '64, 

 pp. 30, 31, 75, 99.) In all 

 these cases we see that the 

 action of a violent current, 

 like repeated contact, leads 

 (as ENGELMANN, '69, p. 321, 

 has suggested) to results 

 which can be accounted for 

 on the ground of reduced 

 cohesion, first, tendency to 

 spherical aggregation, and, 

 finally, disintegration (Fig. 

 31). 



After having studied the 

 effect of the electric current 

 upon Protista and simple 

 cells, it remains to consider, 



very briefly, its effect upon muscle and upon nerve. Since 

 CALDANI discovered, in 1756, that frogs, shortly after death, 

 could be stimulated to movement by frictional electricity, and 

 GALVANI and VOLTA, towards the end of the last century, 

 discovered, by the same response, the phenomenon of galvan- 

 ism-, these tissues have frequently been made the subject of 

 careful experimentation. It has been shown, not merely that 



FIG. 31. One of the cells of a stamen hair 

 of Tradescantia virginica. A, unstimu- 

 lated; B, stimulated by an induction 

 current. At a, b, c, d, the protoplasm 

 has aggregated into drops and clumps. 

 (From VERWORN, '89, after KUHNE, 

 '64.) 



