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- 
charis, 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. 
