STRUCTURAL DIFFERENTIATIONS 



145 



as in generalized Hypotrichida (Fig. 79). In all cases they are 

 arranged in longer or shorter rows running straight or spirally, and 

 giving the striped appearance characteristic of the ciliates. Waves 

 of contraction pass from the anterior end posteriorly, cilia of the 

 same transverse rows beating synchronously, those of the same 

 longitudinal rows metachronous! v. 



I 



1 



% 



I. 



^%#^ 



Iff 



Fig. 74. — Types of Ciliata. .-1, Uroleptus pisces (after Stein); B, Cydotrichium 

 gigas (after Faure-Fremiet) ; C, Stcritor polymorpha (after Biitschli) ; D, N ijctothcrus 

 ovalis. (Original.) 



The periplast is variously sculptured in different species, giving 

 the appearance superficially of a different mode of origin of the 

 cilia. In some cases they appear to come from the centers of 

 minute cups or dimples as in Paramecium aurelia; in other cases 

 from longitudinal grooves or furrows between ridges of periplast 

 10 



