During investigations of their metabolism fragments of plant tissue are most commonly incubated in watery solutions in order to replace ihe conditions within the intact organ approximately. -This paper reports experiments performed to investigate; tbe inftuence of a bypotonic medium on several parameters of importance in cell me-i tabolism (protein syntbesis, enzymatic activity, concentrations of metabolic intermedi-| ates, respiration and cell division). -It could be shown tbat protein synthesis is severely inhibited in hypotonicalty exposed potato tuber discs. As a consequence the activities of two debydrogenases of the pentose pliospbate sbunt (glncose-6-phospliate-and 6-phospliogluconate-debydrogenase) are very low as compared with; tissue in air. Since the activated pentose shunt evidently contributes to tbe respira-l tory reaction after derepression of tbe tissue, lowered activities of tbese debydro-| genases must consequently result in lower respiratory activity. This is actually' realized in washed tissne. Likewise tbe mitotic activity is inhibited to a considerable:: extent. -Tbe destruction of permeability barriers witbin tbe cell as a conseqvience I of slicing causes leakage of a variety of metabolites sucb as glucose, glucose-6-phos-| phate, fructose-6-pbosphalc and pyruvate. Thus leaching of metabolic active sul)-| stances is certainly one of the causal factors in Ibe complex reaction of tissue, stices exposed to a hypotonic medium, attbough sucb important parameters as? changed gas conditions and the various effects of altered hydi'ation of cell cytoplasm] must be considered..