428 I' nii'frxili/ of California 1'ti/ilications in Zoology [ VOL. 19 



throughout their extent but also the motorium and from its outer end 

 the membranelle fiber passing to the oral lip and membranelles. After 

 they are once clearly identified with the aid of vital dyes, the motorium 

 and its connecting fibers may be recognized usually with little difficulty 

 in unstained animals. 



The several fibers associated with the base of the frontal, ventral, 

 and marginal cirri are much less distinctly visible. Very careful 

 focussing and regulation of light are necessary, and even then it is 

 usually impossible to make sure of these fibers without the aid of vital 

 dyes. This may be said also of the membranelle fiber along the base 

 of the membranelles. Here the presence of the basal corpuscles of the 

 cilia composing the membranelles and of a compact row of large ecto- 

 plasmic granules (fig. 17) renders this fiber so obscure that a distinct 

 and satisfactory view of it may be had only after dissecting off the 

 membranelles and oral lip and allowing the ectoplasm to disintegrate. 

 Most of the lattice-work complex within the oral lip may be distinctly 

 seen in ventral view. The basal attachments of this to the mem- 

 branelle fiber are indistinct if at all visible, due to the basal corpuscles 

 and large granules of the ectoplasm. 



MOVEMENTS 



So far as I have been able to ascertain, the creeping and swimming 

 movements of the genus Euplotes have not been described. In this 

 species, Euplotes pa-tella, there are evident three specific creeping and 

 six swimming movements. Of the latter, two are much less common 

 than are the other four. 



Being typically of creeping habit, this animal is usually found 

 moving about on the bottom of an aquarium or over various debris and 

 vegetation or on the under-surface of scum or of the surface film of 

 the water. Its creeping movements, therefore, are readily observable. 

 This method of locomotion is effected by means of all the cirri on the 

 ventral surface, aided more or less by the ever active membranelles. 

 The three kinds of creeping movements are: (1) locomotion straight 

 ahead or slightly to the left (orally), (2) a quick, backward movement, 

 usually for a distance about equivalent to the length of the body, or less, 

 and (3) a turn to the right (aborally) through an angle of thirty to sixty 

 degrees. Movements 2 and 3 are comparable with Jennings' "avoid- 

 ing reaction." The accomplishment of movement 2 probably involves 



