The respiratory changes wvhich take place in slices of tubers and tuberous roots have long been of interest to plant physiologists. As early as 1887, the wound respiration of white potato tubers was described (3), and since then many of the factors affecting this phenomenon have been analyzed (17). In recent years, the fact that the developed respiration is resistant to cyanide andl carbon monoxide has attracte(d special attention (18,25 The potato tuber slices, in which there is a striking change within one day, seemii ideally suited for further investigations on the problem of inhibitorresistant respiration. The plan of the present study has been to compare the respiratory mechanisms in freshly-cut and day-old slices, and to ascertain the conditions necessary for the development of the wound respiration. The w\ork has been carried on at two levels: with tissue slices and with isolated cell fractions. Oxygen uptake h1as been used as a measure of respiratory activity, and its coupling to phosphorylation estimated by following phosphate uptake. The respiratory components involved in hydrogen and electron transport have been exanmined by both enzymatic and spectrophotometric techniques. The evidence indicates that during the aerobic incubation of potato slices there is a metabolism-dependent moidification of the mitochondrial respiratory chain, prob-1

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