RELATIONS OF PROTOPLASM TO ELECTRICITY. 207 



movement as distinctly in hairs which had been developed in 

 darkness, and had remained without light for thirty hours, as in 

 any which had grown in the open daylight. According to Du- 

 trochet, it requires a withdrawal of the light for about twenty 

 days to cause an entire cessation of the movement in Chara. 



The effect of very intense light, and the influence exerted by 

 it upon protoplasm containing chlorophyll, will be examined 

 under " Assimilation." 



572. Relations of protoplasm to electricity. Chemical changes 

 within the plant result in the production of electrical currents in 

 protoplasm ; at this point it is proper to examine briefly the 

 effect produced upon protoplasm by continued and induced 

 currents. 



When the plasmodium of a myxomycete is placed between 

 platinum electrodes on a glass slide under the microscope, and 

 a current sent through the mass from one small Grove element, 

 very little if any effect is observable ; but if the current from a 

 few elements is employed, there is at once more or less rounding 

 of the branched mass, and there may also be a reversal of the 

 course of the circulation. When more elements are used, the 

 protoplasm may be killed. If the protoplasm in cells be experi- 

 mented upon, nearly similar phenomena are noticed. Protoplasm 

 is not a good conductor of electricity. JUrgenseu made some 

 experiments on the action of a current from small Grove ele- 

 ments upon the leaf-cells of Vallisneria spiralis. A continued 

 current from one element did not cause any appi'eciable change 

 in the protoplasmic movement ; but when two, three, or four 

 were employed, the current retarded the movement, and after 

 a while completely arrested it. In those cases where the move- 

 ment had been simply checked, it was re-established in full in- 

 tensity shortly after cutting oh" the current of electricity ; but in 

 those where it had been entirely stopped, it did not begin again. 



573. The effect of an interrupted current of electricity is 

 essentially the same as that produced by mechanical shock. 

 The protoplasm generally contracts at certain points forming 

 small roundish masses in the lines of the slender threads, and 

 the movements are arrested. 



574. Hofmeister states that a constant current is practically 

 without any influence upon the circulatory movement in the cells 

 of Chara, but that the interruption of the current produces 

 nearly the same effect as a sudden mechanical shock or a sharp 

 change of temperature. He observed essentially the same phe- 

 nomena in the hairs of the nettle, although in these there was 



