228 EVENINGS AT THE MICROSCOPE. 



ation, or, at the will of the animal, of entire retractation 

 within the abdomen ; and this in an instant : while, as 

 you observed, it is flung about, and dashed from side to 

 side, and bent hither and thither with a sort of insane 

 energy. The means by which these movements are per- 

 formed, you may easily discern in several pairs of muscu- 

 lar bands which run throughout its whole length, their 

 upper insertions being placed high up on the interior of 

 the shell, where, during contraction, you may see them 

 swollen into thick bulbs. 



The foot terminates in two short conical fingers or toes, 

 which can be drawn in or extended, widely separated or 

 brought into contact, at pleasure. By means of these the 

 animal has the power of mooring itself, even to the smooth 

 surface of glass ; and that so firmly that from them it can 

 stretch itself in all directions by turns, now and then shak- 

 ing itself to and fro with sudden violence, as if irritated, 

 yet without letting go its foot-hold. 



While thus anchored, the action of the ciliary wheels 

 produces considerable whirlpools in the surrounding water, 

 as you will see very distinctly when we have recourse to 

 a curious but simple expedient, first invented by Gleichen, 

 and since much used by Ehrenberg, of mixing some 

 colouring matter with the water in which the animal is. 

 I take a little carmine with a wetted hair-pencil, as if I 

 were going to colour a drawing, and allow a small portion 

 of the pigment to diffuse itself in the water which is in the 

 live-box, then, putting on the cover, I quickly replace the 

 whole on the stage, and re-find my little Brachion : and 

 now I again submit it to your observation. 



The whole field is now filled with scattered granules of 

 irregular form and size, of a dark red hue. These are the 

 particles of carmine floating in the water ; particles of 

 alumina, that is to say, stained with cochineal. They are 

 in motion, and their movement is more energetic the 

 nearer they are to the little animal, which is rotating 



