. Carnegie Institution of Washington publication. RESPIRATION AND OXYGEN. 13 TABLE 1.—Respiration of roots and leaves. Species. Root-length (equal volume). Oxygen used in 24 hours per 1 gin. dry weight. Per cent of nitrogen in dry weight. Roots. Seedling Triticum vulgare mm. Do 35 0 82 8 Oryza sativa Do Mature. Lamium album Mentha aquatica Ranunculus bulbosus 39 0 Caltha palustris Do 37 0 Leaves. Phleum pratense Do 29 4 Lolium italicum Do . 24 7 Do 24 8 Phragmites communis
. Carnegie Institution of Washington publication. RESPIRATION AND OXYGEN. 13 TABLE 1.—Respiration of roots and leaves. Species. Root-length (equal volume). Oxygen used in 24 hours per 1 gin. dry weight. Per cent of nitrogen in dry weight. Roots. Seedling Triticum vulgare mm. Do 35 0 82 8 Oryza sativa Do Mature. Lamium album Mentha aquatica Ranunculus bulbosus 39 0 Caltha palustris Do 37 0 Leaves. Phleum pratense Do 29 4 Lolium italicum Do . 24 7 Do 24 8 Phragmites communis Do. ... .... 12 8 Glyceria Sultans Do 11 2 Ranunculus bulbosus Ranunculus Sultans Do 19 2 Cauvet (1880 :113) demonstrated that roots constantly excrete C02 and that this excretion is weaker at night than during the day. He also determined that the root does not absorb C02 from the soil, and that the C02 excreted has for its immediate effect the solution of the solid matter of the soil for the use of the root. Schwarz (1883 :135) at first assumed that the production of root- hairs was suppressed in many plants because of lack of oxygen. The addition of abundant oxygen to the water-cultures failed to cause the production of hairs and he concluded that the absence of hairs could not be ascribed to its lack. It seems probable, however, that the amount of oxygen used was too great for growth. Van Tieghem and Bonnier (1882) found that gm. of peas, sealed in air, yielded per cent of carbon dioxid and reduced the oxygen to per cent in the course of 2 years. Bonnier and Mangin (1884 : 215, 220) pointed out that, in pro- longing the sojourn of plants in containers, the respiration was no longer normal. At the end of a certain time, when nearly all the oxygen was consumed, fermentation proper entered and carbon dioxide was released in great quantity without oxygen being ab- sorbed. They were also (1885) the first to show that respiration i
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