In this country a search in the rubbish left by a spate or freshet along a riverside is sure to furnish many floating fruits or seeds. Most of these are small and rather difficult to see. Perhaps the most interesting are those of the Sedges. The real fruit is only about one-sixteenth of an inch in size, but it is enclosed in a little sack or bag a quarter of an inch long and with a narrow opening, so that it floats quite easily. Many willow branches, pondweeds, hornweeds, and the like, are also found in the rubbish left by floods, and these can often take root. It is, however, in the exquisite modifications of those fruits which are blown by the wind that we find the most beautiful contrivances of all. They are effective also. Seeds are often so small as to be like dust particles, and such may be carried in the air to almost incredible distances. That of _Goodyera repens_ weighs only 1/200,000,000 of a pound, that of _Monotropa_, ·000,000,006 lb. It is no doubt by the wind that the spores of lichens are carried from one mountain to another. On a map of the world the distance from the Arctic to the Antarctic, between the North and South Poles, seems enormous. Moreover, the amount of water, desert, tropical forest, and cultivated land in this extent of country is very great. There are but few rocks on which lichens could manage to grow. And yet of the Antarctic Lichens in the South Polar regions, and which are also European species, more than 73 per cent. are found in the Arctic or North Polar regions.[116] [116] Darbishire, _Trans. and Proc. of Bot. Soc. Edin._, vol. 23, part 1. An Arctic lichen spore probably travelled from Scandinavia to the German and Swiss Alps, another journey took it to the Atlas Mountains, thence to Abyssinia, again to Mount Kenia, and from there, somehow, it wandered to the South Orkneys or King Edward VII Land. While talking of lichens, one must not forget the Manna of the Bible (_Lecanora esculenta_) and two other species, which form warted, wrinkled masses on rocks. It breaks off and may be carried away by the wind, or in heavy rain it may be washed into depressions of the soil, where a man can pick up 8 to 12 lb. in a day. It "is used as a substitute for corn in years of famine--being ground in the same way and baked into bread.... It is also remarkable that all the great so-called rains of manna, of which news has come from the East to Europe, especially those of the years 1824, 1828, 1841, 1846, 1863, and 1864, occurred at the beginning of the year, between January and March, i.e. at the time of the heaviest rains.... The inhabitants of the district actually thought that the manna had fallen from heaven, and quite overlooked the fact that this vegetable structure grew and developed (although only in isolated patches and principally as crusts on stones) in the immediate neighbourhood of the spots where they collected it."[117] [117] Kerner, _Natural History of Plants_, vol. 2.