vi CONTENTS. 
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fluence of Spring.—Flow of Sap.—Direction of the Currentsx— 
Force of Circulation-—Experiments of Dr. Hales.—Endosmose. 
—Value of Sap.—Toddy.—The spring of the Desert—Milk-sap. 
—Caoutchouc.—W oorari poison.—Vegetable milk.—Cow-tree. 
—Structure or a Leaf.— Singular leaves in Australia.— The 
heap of Onions.—Green colour of Plants. —Influence of Light.— 
Curious effects of Light on some Plants.—Experiments of Mr. 
R. Hunt.— Influence of Coloured Light.—Source of wood: ex- 
periments on it.— From Air.—Composition of Air.—Carbonic 
Acid.— Experiment on a sprig of mint.—Function of Leaves.— 
Sleep of Plants.—Carbonic Acid in the Air.—Purifying influence 
of Plants.—Mushroom tribe.—Singular properties of.—Change 
and Fall of the Leaf. . . : : A . 43 
CHAPTER III. 
THE ADULT TREE. 
Section of the Stem.—Exogenous and Endogenous Trees. — 
Rings represent years.—The Food of Plants.—Source of Nitro- 
gen. —Ammonia.— Rain.—Alkalis.— Fern-balls.— Manures.— 
Liebig’s discoveries.—Geography of Plants. —Visit to a Salt-dis- 
trict.—Curious anecdote of a Hay-stack.—Silex in Plants.— 
Tabasheer.— Flowering-time of the Tree.—Effects of Light 
on colour of Flowers. —The Chameleon-flower.— Odour of 
Flowers.—Flowers expanding at Night.—The Sleep of Plants.— 
—Linneus and his gardener.— Flower-clock.—Irritability of 
