I. THE RESPIRATORY METABOLISM

John R. Murlin ¹ and With the Assistance of William R. Murlin and Jean D. Watkeys

¹ From the Department of Vital Economics, University of Rochester, Rochester, N. Y.

1. Respiration studies on single castor beans, made by means of the Brodie-Warburg method, at various times after the start of germination, as well as studies on groups of germinating beans over periods of 3 to 8 days, made by a simple procedure involving analysis of the respired air by the Haldane method, consistently give respiratory quotients from 0.30 to 0.58, indicating the conversion of the oil to carbohydrate.

2. The R.Q. varies with the stage of germination, the lowest point occurring when the new growth (hypocotyl) measures from 20 to 35 mm. in length.

3. The R.Q. of the young plant (cotyledons and hypocotyl), separated from the endosperm and studied in the same apparatus, varies from 0.78 to 1.00. It is invariably high enough to indicate considerable combustion of sugar. The R.Q. of the endosperm alone is low, but usually somewhat higher than that of the entire germinating structure.

4. On the same unit of moist weight the young plant (cotyledons and hypocotyl) produces about 2.6 times as much CO₂ as the endosperm, whereas it absorbs only 1.3 times as much O₂.

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