156 Proceedings of the Royal Physical Society. 



consists of a moving protoplasm, branching and coalescing 

 like the pseudopodia of the animal now under consideration. 

 Now we cannot suppose that the protoplasm of the Ana- 

 eharis, the Coryne, or the pigment corpuscle is composed of 

 cohering fibres. 



It is true we are at a loss to understand the phenomena 

 of the movements of the sarcode ; indeed, we can scarcely 

 form any conception of a power capable of producing such 

 movements, or of its mode of action ; but we are equally at 

 fault with regard to the movements of muscular fibre, or 

 those of cilia. It is probable that in all these cases the 

 movements are due to modifications of the molecular attrac- 

 tion of the tissue, caused by a corresponding modification of 

 the vital force, and analogous to the modification in the 

 cohesive and molecular forces effected in organic matter by 

 alterations of electro-polarity. Thus, if a globule of mercury 

 be rendered positive by contact with the anode of a voltaic 

 arrangement in a solution of hydrocloric acid, its coerced 

 affinity for this solution will overcome the attraction of co- 

 hesion between its own molecules, and it may be drawn out 

 in threads, which will remain permanent while connected 

 with the battery ; the moment, however, the mercury is re- 

 leased from its forced polarity, by touching it with the 

 kathode of the battery, all the threads of the metal are 

 drawn in with convulsive violence, and it assumes its 

 globular state, being repelled by the acid which before 

 attracted it, and resuming its cohesive form. Another very 

 beautiful instance of movements produced by the modifica- 

 tion of cohesive or capillary attraction is shown in an ex- 

 periment which I have lately perfected. A sheet of mica 

 is laid on a moistened plate of brass ; a drop of sulphuric 

 acid is gently deposited on the mica, and the brass and the 

 drop connected with the extremities of a weak induction 

 coil ; as long as the machine is at rest the drop remains 

 globular and quiet, but the moment the electric current is 

 set in motion, the drop begins to put forth pseudopodia, as 

 it were, and spreads itself over the mica in a beautifully 

 branched figure, exactly resembling the pigment corpuscle 

 of the fish and the movements of its protoplasm. 



