Morphometric study of Lemna gibba in relation to the use of compartmental analysis and the flux-ratio equation in higher plant cells

Morphometric characteristics of Lemna gibba L. cells have been estimated. The mean relative volumes of the wall, of the cytoplasm and of the vacuoles were 0.03, 0.32 and 0.65, respectively. The distribution of the individual values has been studied: for instance 29% of the cells had a mean relative volume of the vacuoles close to 0.73, 39% to 0.68, 19% to 0.61 and 13% to 0.51. The mean value and distribution of the surface areas of the tonoplast and plasmalemma were also determined. This allows us to discuss the active or passive character of the transport of various substances at the plasmalemma and at the tonoplast, according to the usual flux-ratio approach. The feasibility of such an approach in ordinary (non-giant) living cells is discussed with regard to the degree of reliability of the measurements which can be performed with such cells.