I20 PLANT RESPIRATION 



cally after a temporary immersion in sugar solutions, where 

 they absorb considerable quantities of the dissolved sugar. 

 An increase in the oxygen respiration after a dose of sugar was 

 also observed by Kostychev^ in the case of wheat seedlings. 

 An enormous consumption of sugar may be observed in some 

 very energetically respiring plant organs. For example, this 

 is the case in the respiration of the spadix of Arum which devel- 

 ops a large amount of heat.- The number of cases which 

 exhibit an energetic oxidation of sugar could be further aug- 

 mented but it is sufficient to refer to the literature just cited. 

 Nevertheless Detmer^ years ago proposed a theory which 

 supposes that the "hving" protein substance of the protoplasm 

 functions as the immediate material for respiration. According 

 to Detmer, the sugars are said to be used only to regenerate the 

 proteins which are used in respiration. This assumption con- 

 tradicts an abundance of facts recently established beyond 

 question. At present it offers only historical interest and an 

 illustration of the over-emphasis of the role of proteins in phys- 

 iological metabohsm, which was very general at the end of the 

 iQth century. It was generally assumed (without reasons 

 founded on fact) that proteins constitute the most important 

 component of the protoplasm and therefore take part in all 

 material transformations. Life was regarded as a continuous 

 breaking down and rebuilding of the protoplasmic framework 

 and especially of the "living" protein material."^ On this 

 point Pfefifer^ writes very decisively in his text book of plant 

 physiology: "It is of course essential that the specific structures 

 of the protoplasm to which it owes its hereditary character 

 must not be irreparably disorganized by respiration. In all 

 these considerations it is unjustifiable to content oneself with 

 the hypothetical notion that the destruction of protein and 

 the protoplasmic elements is essential for the operating 

 metabolism." 



' Kostytschew, S. Biochem. Z. 15: 164. 1908; Physiol.-chem. Untersuch. iiber Pflan- 

 zenatmuiiK. 1910. Russian. 



- Kraus, G. Ann. jard. hot. Buitenzorg. 13: 217. 1896; and others. 



'Detmer. Jahrb. f. wiss. Hot. 12: 287. 1879; Ber. d. bot. Ges. 10: 2or, 442. 1892; 

 Lehrb. d. Pflanzenphysiol. 1883. P- iS3- 



■• Pfliiger. Arch. ges. Physiol. 10: 251, 641. 1875; and others. 



' Pfeffer, W. Pflanzenphysiol. 2nd. ed. \'o]. i, p. 553- 1897. 



