64 STUDIES IN ANIMAL LIFE. 



The Eotifera (also, and more correctly, called 

 JRotatoria) form an interesting study. Let us glance 

 at their organization : 



There are many different kinds of Eotifers, vary- 

 ing very materially in size and shape, the males, as 

 was stated in the last chapter, being more imper- 

 fectly organized than the females. They may be 

 seen either swimming rapidly through the water 

 by means of the vibratile cilia called " wheels," be- 

 cause the optical effect is very much that of a 

 toothed wheel, or crawling along the side of the 

 glass, fastening to it by the head, and then curving 

 the body till the tail is brought up to the spot, 

 which is then fastened on by the tail, and the head 

 is set free. They may also be seen fastened to a 

 weed, or the glass, by the tail, the body waving to 

 and fro, or thrusting itself straight out, and setting 

 the wheels in active motion. In this attitude the 

 aspect of the jaws is very striking. Leuwenhoek 

 mistook it for the pulsation of a heart, which its in- 

 cessant rhythm much resembles. The tail and the 

 upper part of the body have a singular power of 

 being drawn out or drawn in, like the tube of a 

 telescope. There is sometimes a shell or carapace, 

 but often the body is covered only with a smooth 

 firm skin, which, however, presents decided indica- 

 tions of being segmented. 



The first person who described these Eotifers was 

 the excellent old Leuwenhoek,* and his animals 



* LEUWENHOEK: Select Works, ii., p. 210. His figures, how- 

 ever, are very incorrect. 



