. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. FORAMINIFERAN PROTOPLASMIC MOVEMENT 111 fl c> f2. A B FIGURE 5. Arrangement of actively moving filaments (fi and f2) of pseudopod. A, cross- section ; B, side view. Direction of movement shown by arrows. The moving material is assumed in the diagram to be in the form of a semi-cylindrical filament, turned back upon itself at the tip, with the flat surfaces opposed. The shearing force is assumed to be between the adjacent surfaces and is designated by the short curved lines. The small hook-like structures represent the act
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. FORAMINIFERAN PROTOPLASMIC MOVEMENT 111 fl c> f2. A B FIGURE 5. Arrangement of actively moving filaments (fi and f2) of pseudopod. A, cross- section ; B, side view. Direction of movement shown by arrows. The moving material is assumed in the diagram to be in the form of a semi-cylindrical filament, turned back upon itself at the tip, with the flat surfaces opposed. The shearing force is assumed to be between the adjacent surfaces and is designated by the short curved lines. The small hook-like structures represent the active shearing mechanism, which at present is completely unknown. It must act in the direction indicated by the small arrows, and it must be capable of acting against the same mechanism on the opposite semi-cylinder. All other properties of the mechanism remain undeter- mined. As diagrammed here one could imagine the gel filament with its active mechanism to be similar to a millipede of relatively enormous and indeterminate length, folded back upon itself at the tip and with the legs of one portion of the body pushing against those of another portion throughout the length of the pseudopodium. The basic idea is not new, but was proposed in somewhat different form by No- land (1957), in a general manner and without detailed application. In discussing the structure of protoplasm in Amoeba protcus Noland stated (p. 4), ". . the endo- plasmic molecules, some of them at least, must be quite linear in form. If one lets his imagination have free play he might compare the molecules of the plasmasol to a writhing mass of centipedes, each hanging on to his neighbors with a leg or two, but often losing hold and grasping any other one that comes with reach. Thus the whole mass, though moving, would maintain a certain coherence, so that a tug at one centipede would be communicated some distance into the ; Further- more, in expressing doubt that the pressure differential theory c
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
