228 EVENINGS AT THE MICROSCOPE. 



great elongation, 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 performed, you may easily discern in several pairs 

 of muscular 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 separ- 

 ated or brought into contact, at jDleasure. 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 shaking itself to and fro with sudden vio- 

 lence, as if irritated, yet without letting go its foot-hold. 



While thus anchored, the action of the ciliarv 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 



