Read it through once

Birds are known to travel enormous distances. It is said that one little Arctic bird travels from Heligoland to Morocco in a single flight. It would not, at first sight, seem likely that seeds and fruits could be carried by birds; yet Darwin saw that this might possibly be the case. The mud and slime in which so many birds find the small insects which they require is full of seeds. An Austrian botanist, Kerner von Marilaun, examined the mud scraped from the beaks, feathers, and legs of a number of wading and marsh-birds. He found in it the seeds of no less than thirty-one different water and marsh plants (Grasses, Sedges, Toad-rush, etc.). This showed, as is very often the case, that Darwin was the first to discover a very important point. It is also interesting to find that these ugly little freshwater mud and marsh plants are at home almost everywhere, from the Arctic circle to Tierra del Fuego and from Peru to Japan.