Elementary botany . Then prick with a needle a smallhole through the paraffine or varnish. Immerse the plant in water andplace in sunlight as before. The gas now comes from the puncture throughthe coating of the cut end, and the number of bubbles given off during agiven period can be ascertained by counting. If we duplicate this experi-ment by placing one plant in weak light or diffused sunlight, and another inthe shade, we can easily compare the rapidity of the escape of the gas underthe different conditions, which represent varying intensities of light. Wesee then that not only is sunlight n
Elementary botany . Then prick with a needle a smallhole through the paraffine or varnish. Immerse the plant in water andplace in sunlight as before. The gas now comes from the puncture throughthe coating of the cut end, and the number of bubbles given off during agiven period can be ascertained by counting. If we duplicate this experi-ment by placing one plant in weak light or diffused sunlight, and another inthe shade, we can easily compare the rapidity of the escape of the gas underthe different conditions, which represent varying intensities of light. Wesee then that not only is sunlight necessary for the setting free of this gas, butthat in diffused light or in the shade the activity of the plant in this respectis less than in direct sunlight. 127. What this gas is.—If we take quite a quantity of theplants of elodea and place them under an inverted funnelwhich is immersed in water, the gas will be given off in quitelarge quantities and will rise into the narrow exit ot the funnel. 62 The funnel should be one with a short tube, or the vessel onewhich is quite deep so that a small test tube which is filled withwater may in this condition be inverted over theopening of the funnel tube. With this arrange-ment of the experiment the gas will rise in theinverted test tube, slowly displace a portion ofthe water, and become collected in a sufficientquantity to afford us a test. When a consider-able quantity has accumulated in the test tube, wemay close the end of the tube in the water withthe thumb, lift it from the water and invert. A Flg-65 Apparatus for col- The gas will rise against the thumb. A dry Acting quantity of ° J oxygen from elodea. soft pine splinter should be then lighted, and (Detmer.)after it has burned a short time, extinguish the flame by blowingupon it, when the still burning end of the splinter should bebrought to the mouth of the tube as the thumb is quickly movedto one side. The glowing of the splinter shows that the gas isoxygen.
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Keywords: ., bookauthoratk, bookcentury1900, bookdecade1900, booksubjectbotany
