170 



PARAMECIUM AND PLEURONEMA. 



midst of the body, about as far from one side as the other, and 

 extends from one half to two thirds of the length of the animal. 

 According to Balbiani's observations upon a closely allied species, 

 when the eggs are laid they pass out from the ovary through an 

 aperture near the mouth. 



The organs of locomotion of Paramecium are mostly very 

 short, closely-set, vibrating cilia, which completely cover the 

 body, and are arranged in numerous longitudinal lines. At the 

 tail (T) there are quite a number which are much larger and 

 longer than the others ; and in the vestibule (v] of the mouth 

 (//?.) they have more of the character of lashes, on account of their 

 large size and frequent flexions toward the latter as they assist 

 to throw off an unwelcome morsel of food, or enforce the entrance 

 of some vagrant bit which may happen to be too large for the 

 efforts of the smaller cilia in the throat. The apparent intelli- 

 gence with which one, two, or three of these lashes are used like 

 so many fingers to turn over, or lift up and rearrange some dif- 

 ficult, more than mouthful of food, is very striking, when we 

 consider the low grade in which the Infusorians stand among 

 living beings. How often have 1 observed one of these creat- 

 ures trying to get a great globule of food into the throat, and 

 seen it whirl it first one way then another, and finally, after 

 several efforts, the attempt being given up with a sudden, petu- 

 lant rejection of the desired mor- 

 s:-l, throw it away with a toss far 

 from the influence of the ciliary 

 vortex! 



The next Infusorian which I 

 shall make mention of is Pleu- 

 ronema; one which I have already 

 described (p. 148) pretty fully, and 

 will therefore introduce here (fig. 

 99) merely to draw your atten- 

 tion to the fact that its vestibular 

 disc (fig. 99, m) has a greater ob- 

 Fi g . 99. liquity than that of Paramecium ; 



me 



