426 University of California Publications in Zoology [VOL. 19 



the animal, when the support was sufficient to carry the body along 

 with the needle. As to how this curious feat may be accomplished I 

 can only conjecture the possibility of a secretion present on the cirrus. 



MEMBRANELLES 



Projecting anteriorly from along the dorsal base of the oral lip, the 

 series of membranelles turn ventrad on the left in a gracefully twisting 

 curve and continue along the left side of the cytostome and pharynx 

 to end in a hooklike turn at the apex of the pharynx. Yocom (1918, 

 p. 4) has aptly likened the twisting and general shape of this con- 

 tinuous series to the collar and lapel of a coat. His splendid detailed 

 description may be referred to for the more minute structure of these 

 organelles. A further description concerning only their attachment 

 and their relation to the neuromotor apparatus will be given later 

 under the heading "Experimental." However, the considerable dis- 

 cussion on the actual relations of the cilia which compose the mem- 

 brancllcs described for various Euplotcs is here worthy of note. 

 Obviously, these relations condition the shape of the membranelles. 

 For E. harpa, Wallengren (1901) describes and figures the mem- 

 branelles as triangular in shape. Minkiewiez (1901) found those of 

 E. vannws to be of a similar shape. Yocom 's discussion of this point 

 would seem to favor the view of the above authors, although he does 

 not refer to the particular shape of a membranelle. Griffin (1910a), 

 on the other hand, states that after repeated examination of these 

 structures in E. worccsteri, he is inclined to believe that the mem- 

 branelles which are nearly rectangular in shape are composed of dis- 

 tinct cilia ' ' with movements so perfectly coordinated that they act and 

 ordinarily appear as a single and delicate band" (p. 299). Mobius 

 (1887) had come to the same conclusions regarding both the shape and 

 structure of the membranelles of E. harpa. 



Prom the present studies on E. patella, I am convinced that the 

 cilia composing a membranelle in this species are definitely fused and 

 that they are so arranged as to give each membranelle the shape of an 

 elongated triangle. Indeed, those extending over the oral lip (fig. 16) 

 approximate the form of a short cirrus with a very wide base. By 

 means of a dissecting needle, several of those dorsal to the oral lip 

 may be excised, together with a portion of that organ from which they 

 readily separate, and thus the features mentioned above may be 

 exhibited. They may very soon split into bundles of component cilia 



