CHANGES OF FORM IN CELLS. 21 



Positive pole, or Negative pole, or 



electrode electrode 



entrance of current. exit of current. 



Closure - - Contraction 



Current passing - Tetanus 



Opening Contraction. 



After being exposed to the action of moderately strong in- 

 duction currents, protoplasm assumes a spheroidal form. This 

 observation was first made by Kiihne in the amoeba, and has 

 since been corroborated by Neumann, in regard to the colour- 

 less corpuscles of human blood, and by Golubew in those 

 of the frog. Kiihne states that amoebae which have become 

 spherical from the action of induction currents, after a short 

 time recommence their ordinary movements. Golubew makes 

 the same remark, but observes that the movements of the 

 colourless corpuscles of the frog are of a more undulatory cha- 

 racter, though they send out, as usual, pointed processes. 



According to Neumann and Golubew, when strongly irri- 

 tated, the granules in the spherical cells exhibit vibratory or 

 so-called molecular movements. 



Briicke* saw salivary corpuscles burst under the influence of 

 strong induction currents. Kiihne witnessed a similar pheno- 

 menon in an amoeba. 



Kiihne describes the spheroidal condition of the amosba, produced 

 by stimuli, as a kind of tetanus, and considers that, in the state of 

 maximum contraction, these animals assume a spherical form. 



Hermann, however, suggests an essentially different explanation. 

 It is possible, he remarks, that the excitation diminishes certain re- 

 sisting forces which have previously prevented the cell from assuming 

 a spherical form. The spherical form therefore, he thinks, may corre- 

 spond either to the state of rest, or to the state of tetanus. 



Kistiakowsky f has observed an acceleration of ciliary move- 

 ment to be produced by the constant current. 



EngelmannJ gives the following series of laws of this 

 action : 



* Ueber die sogenannte Molecular-beweguny, loc. cit. 

 t Wiener Sitzungsberichte, 1865. 

 t CentralUatL 1868. 



