The Respiration of Acer Buds in Relation to the Inception and Termination of the Winter Rest.

1. The oxygen uptake and carbon dioxide production of intact and dissected buds has been measured, and the effect of oxygen percentage and seasonal changes on these determined. 2. Oxygen partial pressure curves show the oxygen uptake of intact buds to be normally limited by the rate of oxygen diffusion to the respiring cells. 3. The oxygen uptake of dissected bud parts has been found to be limited at much lower oxygen percentages than in the case of intact buds. 4. Although lowering the temperature lowers the rate of oxygen uptake at any given oxygen percentage, it does not greatly change the overall shape of the oxygen partial pressure curve. 5. Observations on seasonal changes in the respiratory behavior of intact buds show that the oxygen limitation is most severe during late summer, is lessened during the autumn when the respiratory capacity of the buds is depressed, and then is largely removed in late winter and early spring as the respiratory capacity of the buds increases.. (6). Dissected bud parts show a strong »Pasteur» effect; the^N₂>_Qco2/Qo₂ air ratio for the bud scales is near 1.0, and for the growing region near 1.4. 7. The limitation of oxygen uptake is reflected by a high aerobic carbon dioxide production resulting in a respiratory quotient greater than unity. 8. The high respiratory quotients have been observed during the months of August and September when the limitation of oxygen uptake is most severe; the H.Q. differs very little from unity when the limitation is not so severe. 9. Lowering the temperature lowers aerobic carbon dioxide production more rapidly than oxygen uptake. 10. These observations are discussed with reference to a growth inhibitor in buds, and a working hypothesis of the nature of rest in these structures is presented. [ABSTRACT FROM AUTHOR]