. Chemical investigations of the rhubarb plant. Rhubarb; Plants. Part II. Water and Solids 65 end. The changes in the petiole were, however, of minor importance in all cases; those of the blades closely resemble the 1936 series. It was to be anticipated that the organic solids of the leaves would dif- fer markedly in behavior according as the leaves were cultured in darkness or in light. In our study of tobacco leaves (85) the organic solids were found to increase rapidly in light and to diminish in darkness; photosynthesis in the tobacco leaf was sufficiently extensive to overcome completely
. Chemical investigations of the rhubarb plant. Rhubarb; Plants. Part II. Water and Solids 65 end. The changes in the petiole were, however, of minor importance in all cases; those of the blades closely resemble the 1936 series. It was to be anticipated that the organic solids of the leaves would dif- fer markedly in behavior according as the leaves were cultured in darkness or in light. In our study of tobacco leaves (85) the organic solids were found to increase rapidly in light and to diminish in darkness; photosynthesis in the tobacco leaf was sufficiently extensive to overcome completely the loss due to respiration. Even in tobacco stalks photosynthesis approximately balanced the loss due to respiration (86) so that little significant change in weight took place. Partly owing to the possibility of transport from the blade to the petiole, the changes observed in the rhubarb leaf were, how- ever, different. Figure 21 shows the behavior; reference to the curves for the whole leaves shows that, during the first 25 hours, all leaves lost small quantities of organic solids; subsequently the LW leaves increased slightly in organic solids but, at the end of 165 hours, had diminished again to the level reach- ed in 25 hours. The DW leaves continued to lose organic solids for 93 hours, but the DG leaves, after the initial drop, increased in organic solids even above the initial weight and retained this increased amount to the end. It would seem that photosynthesis played a significant part during the culture of the leaves in light, while the leaves cultured upon glucose in darkness ob- viously acquired organic solids from the culture solution. FiK. 21 Organic Solids V/hole â¢^ Leaf 'DG "-^ ^ / ; / LW ^ \ ^W Blade Y\DW \\ DG ^.-\ ~*"- .-o ^ \r-^^^^« ~»-~. LW â â « Petiole ⢠⢠DG / -^ . // LW^~^ // ,⢠' â ^^ \ â _o DW 1 r° 1 - 0 Hours 100 200 Fif?. 22 Total N Whole Leaf ^DW ^^^ _c. Blade \ \dw \ ^^^ LW Peti ole ^ ⢠V' LW . / >
Size: 991px × 2523px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookpublishernewhavenconnect, booksubjectplants
