A total of 146 species of angiosperms belonging to 35 taxonomically diverse families were screened for the isolation of living mesophyll cells from the leaves. Seventy-three species belonging to 22 families, on mild maceration in mortar with the isolation medium (pH 5·8) containing 0·7 M mannitoJ, 2 mM EDTA, 5 mM MgCl₂, 5 mM K₂HPO₄ and 1 mM NaNO₃, followed by fractional centrifugation, yielded intact mesophyll cells as seen under a research microscope. The high frequency of cell release, associated with the high percentage recovery of chlorophyll in cells was a common feature of most of the plant species examined by us. Nearly 87% of the chlorophyll present in the leaf could be recovered from the isolated cells inDolichos lablab. The isolated cells retained active photosynthetic carbon metabolism as evidenced by high rates of ferricyanide reduction as well as carbon assimilation.

The relationship of leaf nitrate reductase (nr) and proteinase activities to the grain protein level and grain yield was investigated in four species of grain amaranth (Amaranthus hypochondriacus, A. caudatus, A. cruentus andA. edulis). A strikingly positive correlation between the leaf proteinase activity and the grain protein content was found.A. edulis with higher grain protein level possessed high leaf proteinase activity, whileA. hypochondriacus, with relatively lower grain protein content had lower leaf proteinase levels. Although there was no definite correlation between the leaf proteinase levels and the grain yield, the integrated leafnr activity was positively correlated with the grain yield. The total nitrogen content per plant seems to be dependent on the extent of root growth and the levels ofnr activity in leaves.

Gas chromatography of essential oils ofCymbopogon showed striking interspecific differences in their major constituents. The two species of lemongrass,C. flexuosus andC. pendulus contained large amounts of citral while the citronella grass species,C. nardus andC. winterianus showed comparable amounts of geraniol, citronellal and citronellol. The essential oil ofC. martini was composed only of geraniol and citronellol and was therefore quite different to the other species. The gas chromatography profiles enable the identification of various species yielding essential oils characterised by their specific constituents.

Photoacoustic spectroscopy was applied to determine the distribution of chlorophylla in the abaxial and adaxial sides of the leaf in 27 species of angiospermous plants. Two distinct patterns were observed in the ratio of the level of chlorophylla in the abaxial to adaxial side of the leaf in the monocotyledons and in dicotyledons plants. The ratio was not correlated with the C₃ or C₄ type of photosynthetic pathways.