PEOTOPLASMIO MOVEMENT. 401 



into itself. After as much as ten seconds' stimulation Amoebee 

 will recover their original appearance and movement. Myxo- 

 raycetes appears to behave in essentially the same way. The 

 phenomena are, however, somewhat altered here, as the size of 

 the object admits, as a rule, of partial excitation only.^ 



Rhizopods (Miliola, Actinosphserium) draw their pseu- 

 dopodia in when electrically excited, and these as a rule shortly 

 become varicose.^ 



A stronger excitation is required to excite the pseudopodia 

 which lie at right angles to the direction of the current than 

 for those which lie parallel to it. The protoplasmic threads of 

 vegetable cells which exhibit circulation behave in a similar 

 manner (Tradescantia type).^ 



So long as the excitation is weak, as with amoeboid proto- 

 plasm, slowing and stopping of the movements generally occurs 

 at first, then varicosities, lumps, &c. are formed. Especially 

 instructive are the phenomena in the case of partial excitation. 

 Kiihne^ observed (cp. fig. 2, p. 402) with Tradescantia, "that 

 at one portion of the cell the stronger threads drew together, 

 forming lumps and spheres, in which, after a resting period, 

 movement of the granules commenced, which might have beoi 

 mistaken for molecular movement if it had not been evident 

 that the granules obeyed another impulse, owing to the very 

 altered condition of the ground substance. As soon as the 

 lumps and spheres became flattened again they moved onwards 

 one by one with the streams in the neighbourhood which had 



' Kiihne, ' Unters. lib. d. Protoplasma, &c.,' p. 75, et seq. 



2 M. Schultze, ' Das Protoplasma, &c.,' p. 3S ; Kiihne, ' Uuters., &c.,' p. 56. 



^ M. Schultze, 'Das Protoplasma, &e.,' p. 43, et seq. Heideuhain, "Noti- 

 zen iiber die Bewegungserscheinungen, welehe das Protoplasma in den Pflan- 

 zenzellen zeigt.," ' Stud. d. physiol. Instit. zu Breslau,' 2 Heft, p. 66, 1S63. 



•* Kiihne, ' Uuters. iiber das Protoplasma, &c.,' p. 99 (Tradescantia). 

 W. Velten, " Einwirkung stromender Elektricitat auf die Bewegung des 

 Protoplasma, &c.," 'Sitzsber. d. Wieuer-Mathem. Naturw.,' CI. Ixxiii, p. 351, 

 et seq., 1876. The phenomena of swelliug described by Velten have not 

 been observed by other observers, nor by myself. I must state that, at any 

 rate, when the current is not over maximal, they do not take place in any 

 marked manner. 



