48 



INVERTEBRATE ANIMALS. 



their liberation from the body of the parent, are developed 

 into fresh individuals. ■. t- j, 



Epistylis, which is a good example of the fixed Infusoria, 

 may be regarded as essentially similar to Parammcium in its 

 anatomical structure. In place, however, of a single free- 

 swimming organism, we have now a colony of more or less 

 closely related beings, the whole assuming a plant-like form, 

 and being rooted to some solid object. The colonies of 

 Epistylis may not uncommonly be found adhering to the 

 stems of water-plants or to the backs of our common water- 

 beetles, and the trained eye readily recognizes them as a 

 grayish-white down or nap. On placing a portion of this 

 under the microscope, we see a number of little oval cups or 

 " calyces " supported upon a branched stem. Each cup con- 

 tains a sarcode-body, essentially the same as Paramcedum 

 in structure, consisting of granular sarcode, with vacuoles, a 

 nucleus, and a contractile vesicle. The end of the cup farthest 

 from the stalk terminates in a rounded aperture, through 

 which there can be protruded a ciliated disk. On one side 

 of this disk is the aperture of the mouth, leading into a kind 

 of gullet, which is also furnished with large vibrating cUia. 

 This, in turn, opens directly into the soft, granular sarcode 

 of the abdominal cavity, which exhibits a constant though 

 slow rotation. 



Fig. 11. — Ciliated InftiBoria. a Va(iinicola ; h i<5?<^<orJ/7///<'r/. the Trumpet Animalcule; 

 c Group of VorticelltB ; d Detaclied bud of Voriic^lta. 



A still commoner and equally beautiful example of the 

 Stalked Infusoria is the so-called Bell-auimalcule ( Vorticella 

 Fig. 11, c), which may be found in any stagnant pool attached 



