Quarterly Journal of Microscopical Science, Vol s3-105, 405-414, Copyright © 1964 by Company of Biologists

Flagellar movement of the Sessile Flagellates Actinomonas, Codonosiga, Monas, and Poteriodendron

¹ Department of Zoology, The University, Bristol 8

Water currents set up by flagellar activity are used to bring food particles to the body in each of the sessile flagellates Actinomonas, Codonosiga, Monas, and Poteriodendron. The water currents produced by the 4 organisms are all somewhat different, and, while that set up by Codonosiga is in the expected direction with water flow from the flagellar base towards the tip, the currents set up by the other 3 forms flow from the tip towards the base. In all 4 types the flagellar movements take the form of plane sinusoidal undulations propagated from the base of the flagellum towards its tip, but the different types show adaptive modifications according to the pattern of water currents required. The rates of beat of the flagellum (range 30 to 50 cycles/ sec) and the speeds of propagation of the contraction wave (range 100 to 600 µ/sec) did not differ sufficiently to explain different current patterns. It is suggested that the ‘unexpected’ direction of current flow in 3 of the types may be the result of the presence of flagellar mastigonemes; these are known to be present in the chrysomonad phytoflagellates, to which group Monas and probably also Actinomonas and Poteriodendron belong. Attention is also drawn to the peculiar mode of coiling and unrolling of the flagellum of the bicoecid Poteriodendron.