=Experiment.=--(See Fig. 60). Fill a common quart fruit jar or can with soil and plant in it a kernel of corn, a bean, a cotton seed or seed of some other plant. After the plant has grown to be twelve or fifteen inches high, cut a piece of pasteboard a little larger than the top of the jar, cut a hole in the centre as large as the stem of the plant and make a slit from edge to centre. Soak the pasteboard in melted wax or paraffine candle. Cool it and then place it over the jar, slipping it around the plant stem. Now solder the pasteboard to the jar with melted candle making the joints tight all the way around. Then close up the slit and the hole about the stem. The jar is now completely sealed and there is no way for water to escape except through the plant. The plant should be well watered before the jar is closed. Now weigh the jar and set in the sunlight. Weigh again the next day. The difference in the two weights will represent the amount of water transpired by the plant. The weighings may be repeated until moisture gives out. If it is desired to continue this experiment some time, a small hole should be cut in the pasteboard before it is fastened to the jar. This hole is for adding water to the jar from time to time. The hole should be kept closed with a cork. The amount of water added should always be weighed and account taken of it in the following weighings. While this plant is growing it will be well to wrap the jar with paper to protect the roots from the light. It has been found that the amount of water necessary to grow a plant to maturity is equal to from 300 to 500 times the weight of the plant when dry. This gives us an idea of the very great importance of water to plants. =Experiment.=--Take a few leaves from a plant of cotton, bean, clover or other plant that has been growing in the sunlight; boil them for a few minutes to soften the tissues, then place them in alcohol for a day or until the green coloring matter is extracted by the alcohol. Wash the leaves by taking them from the alcohol and putting them in a tumbler of water. Then put them in saucers in a weak solution of iodine. The leaf will be seen to gradually darken; this will continue until it becomes dark purple or almost black (Fig. 61). We have already learned that iodine turns starch this color, so we conclude that leaves must contain starch. (Five or ten cents worth of tincture of iodine from a drug store diluted to about the color of weak tea will be sufficient for these leaf experiments.)