INFUSORIANS. 



565 



lobster, is an elongated worm-like organism about two-thirds of an inch in length ; it 



multiplies by becoming a spherical cyst, the contents of which break up into minute 



spore-like bodies with spindle-shaped cases, 



which are set free on the bursting of the 



cyst. Each of the spore - bodies also 



ruptures and liberates an amoeba - like 



organism, which ultimately develops into 



an adult gregarina. Another species of 



gregarina lives in the intestines of the 



earth - worm. The Sporozoa are oval or 



spherical monad - like bodies, but without 



flagella, and live as parasites in the cells 



of plants and animals. Cancer and certain 



forms of malaria have been attributed to 



the presence of organisms of this nature in 



the fluids and tissues of the body. 



Ciliated Infusoria, — Order Ciliata. 



The organisms of this 

 group are provided with 

 cilia, limited either to the 

 under side of the body, or 

 forming a circle or spiral 

 at one end, or arranged 

 uniformly over the sur- 

 face. Cilia are slender 

 hair-like processes of the 

 body, which move by 

 bending and straighten- 

 ing themselves in unison ; 

 flagella are larger whip- 

 like organs, and act more 



BELL-ANIMALCULE ( Yovtkclla). 



Slightly magnified ; b, Magnified 600 diameters ; 



n, Nucleus; //;, Muscle-band. 



independently, the range 

 of motion is not so re- 

 stricted, and there are usually only one or two present on a 

 cell. A few typical and common species are described. 



The mussel-animalcule (Stylonychia), common in stagnant 

 water, has the flattened oval body one-hundredth of an inch in 

 length; on the under side is a ring of cilia, and atone end a 

 funnel-shaped depression or mouth {</) with ciliated margin, 

 leading through the dense outer protoplasm into the more 

 fluid inner mass. The two dark oval bodies (c) are nuclei, 

 and the clear spot (h) is the contractile vacuole which contracts 

 rhythmically once in about every ten seconds. The creature can stalk along on 

 the large bristle-like processes, in addition to swimming by means of its cilia; the 



NODDING BELL-ANIMAL- 

 CULE, I'Jpistylis 

 (uat. size — ■^} 1! 

 inch). 



