202 MICROSCOPY FOR BEGINNERS. 



out a carapace, the lorica being a sufficient protection. 

 In the other kinds the carapace is colorless and trans- 

 parent as a glass box, all the creature's organs being 

 plainly visible through its walls. The front part of the 

 body, which bears the cilia or the ciliary disks, and often 

 the long tail-like prolongation of the posterior part, can 

 be drawn within the carapace, and the Eotifer thus shut 

 in and protected from harm. The soft-bodied forms 

 have a similar habit of drawing in the two ends, taking 

 advantage of the hardened skin. This is one of the 

 Rotifer's characteristics. 



The long tail-like part at the posterior end of the 

 body is called the foot, and the two or more short divis- 

 ions at the free end of the foot are, of course, the toes. 

 The true tail of the Rotifer is usually a small affair, 

 which the beginner must not mistake for the more im- 

 portant foot, although it is placed on the foot, some- 

 times quite near the body. It may be represented by a 

 single short point, it may be in two parts and more con- 

 spicuous, or it may be entirely absent. The uses of the 

 foot seem to be to act as a rudder to guide the Rotifers 

 when swimming, as they do in a hurried, headlong way, 

 and also to anchor them when they desire to fish for 

 food. The toes then adhere to the surface of the slide 

 or of any other object, anchoring and holding the ani- 

 mal against the propelling power of the ciliary disks. 

 In some of the group, especially in the commonest of 

 all Rotifer vulgaris the whole foot is arranged with 

 joints that slide on each other like the joints of a spy- 



