Omzettingen van koolhydraten in het blad van Nicotiana tabacum L.

Nicotiana tabacum L. was chosen as an experimental plant for several practical reasons. The plants were grown in large pots in a glasshouse at 22 °C and great humidity in February-March and September-October until 4 normal leaves were present. Each day at 16.00 h the plants were brought into darkness at 28 °C which made them completely free of starch at 10.00 h next morning. At this moment assimilation and other experiments were started.These experiments studied: formation of starch by assimilation at 28 °C; formation of starch from sugar solutions at 28 °C or at 1.5 °C; the significance of carbohydrates for transport of substances in the leaf; the conversion of starch at different temperatures; the accelerated starch breakdown with drying and other related phenomena; the small starch conversion in tobacco with leaf mosaic and in other virus-diseased plants; the changes occurring with drying and fermentation, particularly in carbohydrate content.To kill the enzymes before drying, the plucked leaves after weighing were first treated with boiling ethanol. The further treatment of the leaf extract and the methods of estimating sugars and starch were extensively described. The results of the analyses were thoroughly considered