204 CILIATE FIBRILLAR SYSTEMS 



more branches (Fig. 73) to its adjacent myoneme, with which it 

 apparently united (cf. von Gelei, 1929b). 



He observed also the knob-hke endings of these neuroids, as described 

 by Neresheimer for his neurophanes, but Dierks apparently could ac- 

 count for such knobs as being merely the cross sections of fibrils that 

 happened to be bent near the plane of section. 



The cross striations of the myonemes, described by Biitschli and 

 Schewiakoff (1889), were observed by Dierks in the living organism 

 as well as in his preparations. Johnson (1893) had regarded these as 

 artifacts due possibly to wrinkling of the myonemes, but the regularity 

 of their recurrence and spatial relations seemed to preclude this. The 

 myonemes were usually elliptical in cross section, with the longer axis 

 of the ellipse directed toward the center of the body. This cross section 

 revealed definitely an outer cortex (Plasmahiille) and a medulla (Plas- 

 mamark) (cf. Roskin, 1918). 



Dierks' analysis of Stentor's membranelle apparatus differs in several 

 points from most earlier descriptions. The membranelle platelet, sup- 

 porting each membranelle, represented essentially the aggregate of basal 

 granules of the component cilia. ContinuinV from these granules into 

 the cytoplasm was a basal lamella, the outline of which was clearly 

 rectangular and not triangular as Schuberg (1890) had claimed for 

 his "Basallamelle." Dierks' rectangular lamella could appear as a tri- 

 angle, whose apex might be directed either toward or away from the 

 basal granules, depending upon their position when viewed. For these 

 lamellae were as ribbons, each about three times as long as broad, and 

 each alike was slightly twisted on its long axis. This, according to Dierks, 

 accounted for the erroneous interpretation of Schuberg ( 1890) , Schroder 

 (1906), and others. Not only might the lamellae appear as triangles, 

 but also their inwardly directed "apexes" might then seem to be con- 

 tinued as a fibril ("Endfadchen"). To account for the basal fibril, which 

 Schuberg thought united all of the end fibrils ("Endfadchen"), Dierks 

 observed that his basal lamellae overlapped in such a way that their 

 ends could give the impression of a continuous fiber, comparable in 

 appearance, direction, and extent to Schuberg's described "Basalfibrille." 



3. Euplotes. — As a major group of ciliates, the hypotrichs probably 

 mark the acme of highly differentiated motor organelles (undulating 

 membranes, membranelles, and cirri) the related fibrillar system of 



