. Comparative animal physiology. Physiology, Comparative; Physiology, Comparative. Cilic 643 garded as composite bodies comprising numerous cilia arising from a num- ber of basal granules in a circular or ovoid field/"'"' The ciliary elements ad- here closely to one another in a viscous matrix. The cilia of such a cirrus beat in unison. Membranelles of the adoral region of manv pcritrichs are small platelets of fused cilia beating synchronously. The undulating mem- branes of ciliates such as Blepharisma are long rows of cilia, each adhering to its neighbors. The compound character of
. Comparative animal physiology. Physiology, Comparative; Physiology, Comparative. Cilic 643 garded as composite bodies comprising numerous cilia arising from a num- ber of basal granules in a circular or ovoid field/"'"' The ciliary elements ad- here closely to one another in a viscous matrix. The cilia of such a cirrus beat in unison. Membranelles of the adoral region of manv pcritrichs are small platelets of fused cilia beating synchronously. The undulating mem- branes of ciliates such as Blepharisma are long rows of cilia, each adhering to its neighbors. The compound character of the membrane mav often be demonstrated by its fragmentation by appropriate manipulation with a microdissecting needle.'^ The component cilia, when separated from one an- other, beat quite independently; when they have reunited, the characteristic coordinated activity giving rise to the undulatory movement is restored. Such an activity is the result of the metachronic wave of ciliary activity pro cceding at right angles to the effective and recoverv Fig. 242. Electron micrograph of a cilium from Paramecium, shadow-cast with chromium. From Jakus and Hall.™ Characteristics of Ciliary Movement. The activity of any cilium may be resolved into one or another, or some combination, of three fundamentally different types of *' One of these is pendular movement in which the cilium bends back and forth, flexing only at its base. No differ- ence in the form of the cilium is observed between the effective and the recovery phases of its stroke, the former simply occurring more rapidly than the latter. 1 his type of movement is seen in the cirri of hypotrichs. A second type of movement is a flexural one. Bending begins first at the tip of the cilium and passes toward its base; in recovery, the cilium progressively straightens from base to tip. Such hooklike bending is observed in the latero-frontal cilia of lamellibranch gills. The third fundamental type of ciliary acti
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