USE OF THE MICROSCOPE IN ZOOLOGY. 47 



By continuing to gaze on this marvel of creative skill, 

 you will notice that it every now and then bends its 

 corolla-shaped head down upon the tube, holding it 

 there a second or two, and then raising it up again. 

 What is the meaning of this ? Melicerta is adding a 

 brick to its house ; sometimes you will see the bricks 

 roll off after deposition, in consequence of the material 

 not being sufficiently tenacious. The bricks are 

 made of the same substance so generally used by 

 human architects namely, of clay, the only difference 

 being that the bricks of the rotifer are round and soft. 

 Under a power of about 200 diameters you will 

 observe a singular cavity below the large discs of the 

 head ; this cavity gradually becomes filled with 

 particles of clay ; a number of cilia line the cavity, 

 and by their action cause the particles of clay to 

 rotate rapidly and to be consolidated. When the 

 brick is formed the animal bends down its head and 

 fixes it to the tube, and then begins to form another 

 pellet. The particles of clay, or other adhesive 

 material, are drawn into the cavity where the bricks 

 are formed, by the ciliary action of the discs, a small 

 channel conducting them from the upper portion of 

 the disc to the cavity in question. If portions of 

 indigo or carmine be mixed with the water in which 

 the Melicerta lies, the animal will make use of them, 

 and add rings of red or blue to its dwelling-place. It 

 is impossible, I think, to imagine a more interesting 

 instance of animal architecture than that exhibited by 

 this little creature. 



The Rotifera, from their great transparency, are 

 excellent objects for study ; many, forms, moreover 

 are readily obtained the scum attached to aquatic 

 plants, the dirt in your pipes on the roof of your 

 house, the soil on the roots of the moss of your slated 

 roof, the mud at the bottom of ponds and ditches, will 



