Respiratory Metabolism in Detached Rhododendron Leaves.

Somiie of the measturemiienits (descrile(l l)elow were first made nmanly years ago (21; see 26, 27. 28) as part of an investigationi of the occturrence of the Pasteur effect in plant organis. Mlore recenitly, with the de\veIoIlloent of initerest in factors conitrollinig resp)iratory mietabolismn, our attenitionl was re(lirected to 2 of the plant imiaterials originally sttudie(l. namely rhodlodenidroni leaves for \Nvhich there xx-as evidence of a mlarkedl Pasteureffect and votung seedlings of buckwheat, the one material uisedl for which nio evidence of a Pasteur effect emerged. This paper (lescribes 1 lpart of this work anid is restricte(d to resuilts obtained with detache(d whole leaves of rhodo(lendron. MNany invrestigationis miia(le for conivenience with leaf discs or slices w\ill be (lescribed elsewhere later, for their relevance to mietabolism in the intact leaf is still in some doulbt. T'he experiments described here are largely conicernied with l)ro(lllction alnd consutimptiotl of imietabolites in the leaves in air, in pure niitrogenl, and( on retuirn to air aftera )erio(l in nitrogeii. Particular attention hias been (lirectetl towar(l transitory chaniges in concentrations of glycolytic illtermiie(liates and(l keto-acids as guides to chaniges of rates of glycolysis and of oxidative reactions of the tricarl)oxylic acid cycle. 'I'lTese (lata hlav,e the limitationi of all suclh measuremiients ini that theyrepresenlt average coliceiitratioiis for w hole cells wbiich inay bear little relationi to changcs inl specific metabolic pools associated with glvcolvsis and cycle oxidationis but are nevertheless a necessary p)reinlinary to fturtherwork. Also, because of renewe(l ilnterest elsewhere in the origin of the anaerobic CO., output (24) and of the piossible constumiiption of ethaniol (9Q 10, 29), some attetntioni is given here to these aspects of metabolism. 'I'l'ere is anl extenlsive amiount of literature oni resl)iratorv mietabolismi in p)lant organls, but this is now well (locillmeitedl in text books (4, 16. 25. 26) ani(l chapters in encyclopedic works ( 14, 23) and n1o fuirthierreview will be attemnpted here.