18 THE MICROSCOPE. Feb., 



Put it on the stage of the Excelsior (or other) microscope, 

 add a drop of water, and place over it a cover-glass. 

 With the three lenses together, focus sharply. Exam- 

 ine the leaves very carefully and having found a little 

 brownish object that looks like Fig. 1. a, b, c, or d, watch 

 it attentively and see if in a few minutes the shape of 

 the head will not change, or it may move or disappear 

 with a jerky motion. At times Rotifers are seen sailing 

 in the water or crawling curiously. These animals are 

 so small and sometimes so hidden under the leaves that 

 they are difficult to find, but once seen they will be read- 

 ily recognized. 



Fig. 1. a, b, c and d, represent Rotifer vulgaris as it 

 is usually seen among the leaves. This species has a 

 soft, transparent body, a head (Fig. 2. e.), two ciliated 

 wreaths, f, two eyes, g, a mastax or apparatus for 

 grinding its food, h, an alimentary canal, and a foot, k. 

 The extremity of this foot is forked and secretes a gela- 

 tinous substance by which the animal is able to attach 

 itself. The foot is so arranged that one part can be 

 drawn inside the other like a ship's telescope. At Fig. 

 1. b, the animalcule is attached to the leaf by his foot, 

 and his antennae are extended in search of food. When 

 food is found he expands the ciliated wreathes and sets 

 them in motion. This makes a current in the water and 

 draws the food within reach. It is then sucked into the 

 mouth. This current can be seen and by it the Rotifier 

 can often be discovered. These ciliated wreathes are 

 two cup-like bodies surrounded by cilia or hairs, (Fig. 2. 

 f). The slapping of these hairs one against the other 

 gives the aj)pearance of a rotary motion, and from this 

 motion they receive their name. When not in use these 

 wheels can be drawn into the body, giving the head the 

 shape shown in Fig. 3. m. Some of the Rotifers can de- 

 tach themselves and swim, using these ciliated wreathes 

 as propellers. The Rotifer vulgaris has a peculiar way 



