56 PROTOPLASM 



common salt, are pushed inwards from both sides some way 

 under the cover glass, and act perfectly well, besides being 

 relatively easy to manipulate. 



Since the negative stream did not make its appearance as 

 a rule until after the poles had been closed for two to five 

 minutes, this fact also pointed to its electrolytic origin. 

 This supposition seems to me to be proved with tolerable 

 certainty by further experiments, so that the idea of the 

 drops being influenced by the electric current, as was stated 

 at first, may be dismissed. 



If ordinary drops of oil, placed in glycerine containing 

 some NaCl, be exposed to a constant current between 

 platinum electrodes on the slide, there appears almost imme- 

 diately, provided the amount of NaCl contained in the 

 glycerine be considerable, a powerful centre of extension- 

 currents on the negative edge of the drop, with formation 

 of soap. If the amount of XaCl in the glycerine is slight, 

 it takes some time for a feeble system of extension-currents 

 to be developed on the negative margin of the drop. Next 

 there usually follows again a condition of rest lasting a 

 short time, and then the action of the alkali soon begins to 

 take effect very energetically at the negative margin of the 

 drop. The drop falls into very violent streaming move- 

 ments, becoming transformed into beautiful, perfectly opaque 

 froth, so that I . consider it possible to manufacture very 

 good foam in this way. 



In order to follow out this point still further, I brought 

 drops of oil into the semi-dilute glycerine, which I usually 

 employed, having coloured it slightly with some neutral 

 litmus solution. 1 Then, when the constant current was 

 passed through, employing a battery of five chromic acid 

 elements with platinum electrodes, there immediately ap- 

 peared a blue coloration at the negative electrode and 

 a red at the positive. The blue colour gradually spread 

 out in the form of a triangle, the base of which was at 

 the negative electrode, while its apex was directed towards 



1 This solution I owe to Dr. K. Mays, who has already described the mode 

 of preparing it by means of the dialytic method. See Verh. des medic.- 

 naturhist Vereins, Heidelberg, N". F. Bd. iii. p. 295. 



