. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. CYANOBACTERIAL CURRENTS 479 comparable to the lengths of the measured filaments. Since these filaments were the order of a millimeter or more in length, the tangential current densities should not have fallen off significantly from a filament's surface to the point of measurement; so tangential surface current densities of more than about 30 to 60 nA/cm2 should therefore have been detected. Perpendicular density components of a 'gliding current,' on the other hand, would be expected to fall off inversely to the distance from
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. CYANOBACTERIAL CURRENTS 479 comparable to the lengths of the measured filaments. Since these filaments were the order of a millimeter or more in length, the tangential current densities should not have fallen off significantly from a filament's surface to the point of measurement; so tangential surface current densities of more than about 30 to 60 nA/cm2 should therefore have been detected. Perpendicular density components of a 'gliding current,' on the other hand, would be expected to fall off inversely to the distance from a filament's mid line. Hence, perpendicular surface densities should have been 2 to 3 fold higher than at the measurement point, and ones more than about 100 nA/cm2 should have been detected. Figure 2 shows two sections of the original records, which illustrate these negative results with Oscillatoria princeps. Anabaena About ten filaments of A. cylindrica were explored in a similar way with similar negative results. However, they glided more slowly than O. princeps ( nm/s instead of 1-5 yum/s). As a result, it was possible to vibrate the probe closer to the filaments. Probe-to-filament gaps as small as about 5 /urn were often attained. Furthermore, A. cylindrica has heterocysts at about 100 yum intervals. Therefore, it was possible to search for special heterocyst currents in this species. These results A/c inward I m ^ •v A *wx. r^\ ^ REF ^ REF MOVING REF LEFT REF LEFT REF REF REF REF RIGHT REF DARK /cm upward. __-__. JL \ 1 ^ -JU-J ^TxA^. >/N-~«nA%*»~*r\«H UP /""S^V* DOWN UP ^/SA^^J DOWN REF FIGURE 2. Illustrative records of the unsuccessful search for currents near gliding Oscillatoria filaments, in full strength medium D. Top: probe vibrating perpendicular to filament 2 on 16 September 1984. The probe was to the side of the filament, about 5-10 away in its closest test positions (and 200 ^m away in the reference positions marked 'REF')
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
