which are still unexplained; in fact, it is because this is so that I was anxious to direct attention to the subject. Still I believe the general explanations which have been given by botanists will stand any test.
Let us take, for instance, seeds formed on the same type as that of the ash—heavy fruits, with a long wing, known to botanists as a samara.
Fig. 15.—a. Harpagophyton procumbens (natural size); b, Martynia proboscidea (natural size).
Now, such a fruit would be of little use to low herbs, which, however, are so numerous. If the wing was accidental, if it was not developed to serve as a means of dispersion, it would be as likely to occur on low plants and shrubs as on trees. Let us, then, consider on what kind of plants these fruits are found. They occur on the ash, maple, sycamore, hornbeam, pines, firs, and elm; while the lime, as
