This volume is made up from the writings of naturalists who have told
us of the behavior of animals as they have seen it at first hand and
of the beginnings and the growth of life so far as they know about it.
In selecting these from the wealth of available material the editor
has been guided by this rule: The subject matter must be interesting
to young people; it must be told in a clear and attractive style; and
most important of all, it must deal with actualities.