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Fig. 2.—No Two Leaves are Alike.
If the pupil extends his observation to animals, he will still find the same truth; for probably no two living objects are exact duplicates. If any person finds two objects that he thinks to be exactly alike, let him set to work to discover the differences, remembering that nothing in nature is so small or apparently trivial as to be overlooked.
Variation, or differences between organs and also between organisms, is one of the most significant facts in nature.
Suggestions.—The first fact that the pupil should acquire
about plants is that no two are alike. The way to apprehend this
great fact is to see a plant accurately and then to compare it with
