CILIATED INFUSORIA 



3543 



cilia, by means of which the animal swims about. The long cilia at the upper part 

 form a spiral, within the upper margin of which lies the mouth slit. The mouth 

 opens into a funnel, leading into the sarcode of the interior. The contractile vacuole 

 lies to the right of the mouth slit, and the nucleus forms an elongated beaded 

 band along the length of the body. The 

 ridge of cilia passing down vertically is 

 the mouth fringe of a new animalcule 

 about to be formed by division. A cleft 

 sinks in obliquely at one side of the 

 ridge which assumes a wavy outline and 

 later a spiral; the cleft sinks, till two 

 complete animalcules are formed, with 

 one-half of the nucleus, and a contrac- 

 tile vacuole in each. New individuals 

 may also arise by the budding off of 

 tiny ciliated embryos from the nucleus. 

 The species of trumpet animalcule most 

 commonly met with is of a brilliant 

 green color; frequently clusters of them 

 are found clinging by their pointed ends 

 to the stem of a waterweed. A specimen 

 has been cut into three parts, care being 

 taken to leave a fragment of nucleus 

 in each, with the result that each part 

 has repaired itself into a complete ani- 

 mal; the central part, for instance, de- 

 veloping a head and a tail end. 



The spiral-mouthed animalcules 

 (Spirostomum) are among the largest 



of the class, and visible to the naked eye, especially in sunlight, as slender golden 

 threads about one- tenth of an inch in length. The body is cylindrical, and 

 the surface covered with rows of cilia; the mouth slit extends along half the 

 length of the under side, and is bordered on its left side by a fringe of 

 long cilia. The animalcule is frequently twisted on its long axis, the mouth 

 cilia forming a spiral; multiplication takes place by transverse fission through the 

 middle. 



The curious marine animalcule Arineta is probably related to the ciliated in- 

 fusorians. The stalked club-shaped body is usually fixed on seaweeds or Bryozoa. 

 From the upper end a number of straight sucker-like tentacles proceed; a nucleus 

 and also clear vesicles are present in the body substance; and the embryos are 

 ciliated. 



The bud-bearing Hemiophrya is also a marine animalcule; it possesses a few 

 suckers and a large number of longer prehensile tentacles; on its margin several 

 buds are formed, each containing a process of the nucleus, and the young forms 

 -when liberated are ciliated on their lower surface. The long tentacles capture and 



BUD-BEARING ANIMALCULE, Hemiophrya. 

 (Highly magnified.) 



