. Elementary botany. Botany. RESPIRA TION. 57 8, and the roots measured 20-25/nm. At 3 on the following day, 29 hours after the experiment was started, the roots were examined. Those in the C02 gas had not grown perceptibly, while those in the jar containing air had increased in length lo-iomm. In fig. 48 are represented two of the peas, drawn at the close of the experiment, a represents the one from the C02 jar which had the longest root, b represents one of the longer ones from the jar with air. Here we have also a good comparison with the peas grown in the mercury tubes, since those in
. Elementary botany. Botany. RESPIRA TION. 57 8, and the roots measured 20-25/nm. At 3 on the following day, 29 hours after the experiment was started, the roots were examined. Those in the C02 gas had not grown perceptibly, while those in the jar containing air had increased in length lo-iomm. In fig. 48 are represented two of the peas, drawn at the close of the experiment, a represents the one from the C02 jar which had the longest root, b represents one of the longer ones from the jar with air. Here we have also a good comparison with the peas grown in the mercury tubes, since those in the tube which contained some air were checked in growth to a considerable extent, by the accumulation of carbon dioxide in the small space in the tube, and did not represent a fair comparison of root growth in air and in CO.,. 138. Another way of performing the experiment.âIf we wish we may use the following experiment instead of the simple one indicated above. Soak a handful of peas in water for 12-24 hours, and germinate so that twelve with the radicles 20-2$m»i long may be selected. Fill a test tube with mercury and carefully invert it in â â < vessel of mercury so that there will be no air in the upper end (there may be a small vacuum). Now nearly fill another tube and invert in the same way. In the latter there will be some air. Re- move the outer coats from the peas so that no air will be introduced in the tube filled with the mercury, them one at a time under the edge of the tube beneath the mercury, six in each tube, having first measured the length of the radicles. Place in a warm room. In 24 hours measure the roots. Those in the air will have grown considerably, while those in the other tube will have grown but little or none. The apparatus to demonstrate this was set up at 10 on July 8, 1897. The tube filled with mercury was supported by a clamp, while the tube which was only partly filled was stable enough to support itself until by the ac
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