CHAPTER IV 
RELATION OF PLANTS TO WATER 
LESSON X 
To approximate the amount of water in plants 
Materials——A good supply of several species of Alga. 
Some higher forms of water-plants. Fresh leaves of land 
plants. Pieces of green wood, and dry oak or pine. 
Observation and study.—F rom the water-plants allow the 
water to drip until the surplus has been removed, and lay 
them upon pieces of tin or glass of known weight, and 
weigh, tabulating the exact weight of the plants. Place the 
plants where the water from them may readily evaporate. 
Weigh after intervals of a few hours or a day until they cease 
to lose weight, and show from your results the percentage of 
water in the plants. Treat the green leaves and the pieces 
of green wood in the same way. Split the wodd into small 
pieces in order that the water may evaporate more readily. 
Weigh the piece of dry wood, then place it in an oven or 
upon a furnace or radiator. Does it lose in weight? Can 
you prove that the decrease is due to loss of water? Test 
various kinds of wood to see which contain least water. Do 
you think there is any relation between the strength of the 
wood and the amount of water it contains? 
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