PHYSIOLOGY 



129 



progressing ciliate bends throughout its length and strikes the water 

 so that the organism tends to move in a direction opposite to that of 

 the effective beat, while the water moves in the direction of the beat 

 (Fig. 49, a-d). In the Protociliata and the majority of holotrichous 

 and heterotrichous ciliates, the cilia are arranged in longitudinal, or 

 oblique rows and it is clearly noticeable that the cilia are not beating 

 in the same phase, although they are moving at the same rate. A 



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Fig. 49. Diagrams illustrating ciliary movements (Verworn). a-d, 

 movement of a marginal cilium of Urostyla grandis (a, preparatory and 

 b, effective stroke, resulting in rapid movement; c, preparatory, and d, 

 effective stroke, bringing about moderate speed) ; e, metachronous move- 

 ments of cilia in a longitudinal row. 



cilium (Fig. 49, e) in a single row is slightly in advance of the cilium 

 behind it and slightly behind the one just in front of it, thus the cilia 

 on the same longitudinal row beat metachronously. On the other 

 hand, the cilia on the same transverse row beat synchronously, the 

 condition clearly being recognizable on Opalina among others, 

 which is much like the waves passing over a wheat field on a windy 

 day. The organized movements of cilia, cirri, membranellae and un- 

 dulating membranes are probably controlled by the neuromotor 

 system (p. 63) which appears to be conductile as judged by the 

 results of micro-dissection experiments of Taylor (p. 65). Ciliary 

 movement (Gray, 1928) ; spiral movement of ciliates (Bullington, 

 1925, 1930); movement of Paramecium (Dembowski, 1923, 1929a) 

 and of Spirostomum (Blattner, 1926). 



The Protozoa which possess myonemes are able to move by con- 



