Russel Wallace : Alfred Russell Wallace (sic)
At the recent meeting of the scientists at Cambridge Alfred Russell Wallace, the English naturalist, read a paper on "The Winds as a Seed Carrier in Relation to the Difficult Problems in Geographical Distribution." Some species of plants common in northern climates, many of them being in the Arctic flora, have a wide distribution in the southern hemisphere. There are five prominent causes of seed distribution: First, sea currents; second, birds; third, seeds of marsh plants adhering to the feet of birds; fourth, sticky seeds which attach themselves to the feathers of birds; fifth, wind. The power of the wind in transporting seeds is not yet determined, but there is evidence that it can transport light seeds to a great distance. Dust from the Java eruption a few years ago was found on the decks of vessels at 1,000 miles distant. Most of the northern plants introduced into the south are very light seeded ones, lighter than the dust. Whether or not wind is the agency for transporting these seeds, these evidences go to show that it at least has the power.
Alfred Russell Wallace read a paper on 'The wind as a seed-carrier,' in which he stated that he would by request submit some ideas and ask for data in relation to the ability of the winds, to explain the known distribution of plants. He stated that a large number of arctic plants are now widely distributed throughout the southern and northern hemispheres, so that plants living in New Zealand, Australia, and extreme southern America, are nearly identical with those in high northern latitudes, as also with those found on the high mountains of temperate zones. These occurrences might be explained by the glacial epoch, as Darwin suggested, but that no such glacial epoch is known to have occurred in the torrid zone. His own studies on the fauna of the islands of the ocean had shown that a single occurrence, under favourable auspices, could explain the introduction of a new species in any out-of-the-way place, as illustrated by transfers of seed by sea-currents, by birds in various ways, by human agencies, and especially by the wind. Strong winds carry the heavier seeds short distances, and drop them, to be lifted up and carried again on some future occasion; but the lighter seeds, when once elevated, fall so slowly that even a moderate wind will carry them to great distances. In this way the arctic fauna may be easily transferred toward the torrid zone, and possibly an occasional storm (even one in a century will suffice) may transfer the seeds across the equator, so as to initiate the spread of the same species in the southern hemisphere.