This index will be found useful for statistical purposes. It will show at a glance, at least approximately, how often certain genera and species are affected with malformation, as contrasted with others. The nature of the malformation may of course be ascertained by referring to the particular page indicated by the number. The proportion of wild to cultivated plants may also be approximately ascertained, and the effects of cultivation estimated. The disproportionate frequency with which some species are affected, e.g., Trifolium repens, &c., as contrasted with other closely allied, and perhaps equally common species, under apparently identical conditions, is also made manifest.]

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