The cirri or tentacles, of which three or four pairs are present, are capable of being protruded, and the minute larva swims by means of the ciliary action they produce.
In a few genera the place of the chitinoid coat is taken by a ciliary investment and in most families the structure of the layers is characteristic.
During this time the illusion of a wheel or wheels produced by the ciliary action of the disk had puzzled all observers.
Besides the sphincter pupillae, the fibres of the ciliary muscle are stimulated.
Its stimulant action on the iris and ciliary muscle is employed when they are weak or paralysed.
Such ciliary motion is known in the adult condition of the cells of Volvocaceae, but where this is not the case the reproductive cells are endowed with motility for a brief period.
Together with currents of water induced by the action of the vibratile cilia which are abundant along special tracts on the sides and roof of the vestibule of the mouth and in the walls of the perforated pharynx ("ciliary ingestion").
Ciliary movements, which undoubtedly contribute in bringing the surface into contact with larger supplies of oxygen and other fluids in unity of time, are not so rapid or so extensive when compared with other standards than the apparent dimensions of the microscopic field.
2r, highly magnified, showing the kinds of changes brought about in a few minutes, from A to B, and B to C, by the growth and ciliary movements of the filaments.
This thread gives rise to a spiral ciliated band lying in a depression on the body of each spermatozoid; the large spermatozoids eventually escape from the pollen-tube, and are able to perform ciliary movements in the watery liquid which occurs between the thin papery remnant of nucellar tissue and the archegonial necks.
This appearance puzzled the older observers, who were led thereby to give the name" wheel-bearers "to the group, until the true character of ciliary motion was recognized; for a wheel cannot be i i organic continuity with the support on which it rotates..