SECT. II. 



INFUSORIA. 



69 



50 oth to the is^ooth part of an inch in length, move 

 simultaneously or consecutively in the same direction 

 and back again, as when a fitful breeze passes over a 

 field of corn. These animalcules seize their prey with 

 their cilia, and swim in the infusions or stagnant pools, 

 in which they abound, in the most varied and fantastic 

 manner; darting like an arrow in a straight line, 

 making curious leaps and gyrations, or fixing them- 

 selves to an object by one of their cilia and spinning 

 round it with great velocity, while some only creep. 



Fig. 104. Paramoecinm caudatmn. 

 a a, contractile vesicles ; 6, mouth. 



Fig. 105. Kerona silnrns. a, contractile 

 vesicle ; 6, mouth ; c c, animalcules which 

 have been swallowed by the Kerona. 



These motions, which bring the animalcules into fresh 

 portions of the liquid, are probably excited by the 

 desire for food and respiration. 



None of the Infusoria have regular jointed limbs, but 

 certain families of the higher genera have peculiar and 

 powerful organs of locomotion partly consisting of 

 strong ciliary bristles placed on the anterior in rows, 

 used for crawling or climbing, and partly consisting of 

 groups of strong processes which serve as traction feet, 

 generally trailing behind the animal while swimming, 



