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Analysis of particle motion in sieve tubes of Heracleum
Author(s) -
BARCLAY GREGOR F.,
JOHNSON RICHARD P. C.
Publication year - 1982
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/1365-3040.ep11571598
Subject(s) - sieve (category theory) , brownian motion , particle (ecology) , viscosity , motion (physics) , mechanics , physics , classical mechanics , materials science , composite material , mathematics , biology , quantum mechanics , combinatorics , ecology
. We have cine‐filmed the random motion of microscopic particles, mostly starch grains from ruptured plastids, in sieve tubes of Heracleum mantegazzianum L. and H. sphohdylium Somm. and Lev. Our frame‐by‐frame analysis of the positions of the particles shows that they move much less than calculated when generally accepted estimates for the viscosity of sieve‐lube sap are inserted in the Stokes‐Einstein and other equations for Brownian motion. Our analysis of a film, of similar particles, made by previous workers leads us to disagree with their conclusion that particle movement in sieve tubes was greater than should be expected for ordinary Brownian motion. Particles in their film and in ours moved less than expected even when we allow for the possibility that the particles are restricted by cell walls and by each other. We suggest that the particles move less than expected because the viscosity of sieve‐lube sap may be higher than has been assumed by physiologists.