1918] Yocum: The Neuromotor Apparatus of Euplotcs Patella 353 



in a spiral manner distinctly different from the back-and-forth move- 

 ments of the anal cirri. The smallest cirri are the four marginal cirri, 

 which have a movement similar to the nine cirri described in the pre- 

 ceding sentence. All of these cirri of the living Euplotes are styliform 

 and exhibit a delicate longitudinal striation. By the action of the 

 killing agents or by any change in density of the medium the cirri are 

 broken up into hundreds of component cilia (pi. 14, fig. 3). Such 

 phenomena at once show that cirri are made up of a group of cilia 

 bound together bj' a thin protoplasmic membrane, very much as the 

 hairs of a Avet camel 's hair brush are bound together by the film of the 

 liquid. By a change in the medium the binding substance is broken 

 down or dissolved and the cirri become as a dry brush with the hairs 

 spread apart. 



In a microscopic examination of the cirri it is seen that their com- 

 ponent parts are imbedded in the ectoplasm just beneath the pellicle, 

 for at the base of each cirrus is a dense granular plate the granules of 

 which are the basal granules of the component cilia. Griffin (1910) 

 claimed that the basal granules of each cirrus of E. worcesteri were 

 arranged in several parallel rows indicating that in the evolution of 

 the Hypotricha the cirri had arisen from several rows of cilia. This 

 linear arrangement of the basal granules of the cirri I have been 

 unable to find in E. patella, but rather have found that the granules 

 are arranged in an irregular fashion in the dense, almost opaque, basal 

 plate such as Maupas (1883) described for an unnamed species of 

 Euplotes in which he saw the longitudinal fibers in connection with 

 the anal cirri. When stained with ]\Iallory's stain the granules of this 

 plate color red with the acid fuchsin the same as the fibers and 

 motorium of the neuromotor apparatus, indicating a relation at least 

 of a chemical sort between the two structures. Connecting with each 

 basal granule is the central contractile axis of one of the component 

 cilia of the cirrus. These granules are imbedded in the dense plate 

 which acts .as a firm support or means of attachment for the cirrus. 

 This is in agreement wath Maier (1903), who considers the basal plate 

 as the means of support for the cirrus, but it is to be remembered that 

 in Euplotes patella the function of support is to be attributed only to 

 the dense opaque protoplasmic plate in which the basal granules are 

 imbedded, and that the basal granules themselves are given an entirely 

 different function, which will be fully discussed in a later paragraph. 



Structure of Membranelles. — The membranelles while of a very 

 different shape, upon careful examination are seen to have a structure 



