[Transcriber's note: Page numbers in this book are indicated by numbers enclosed in curly braces, e.g. {99}. They have been located where page breaks occurred in the original book, in accordance with Project Gutenberg's FAQ-V-99. In the HTML version of this book, page numbers are placed in the left margin.] The Syndics of the Cambridge University Press propose to issue a Nature Study Series of which this is the first volume.…
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