s of terrestrial plants, which have only a very
few aquatic members; for these latter seem immediately to acquire, as if in
consequence, a very wide range. I think favourable means of dispersal
explain this fact. I have before mentioned that earth occasionally, though
rarely, adheres in some quantity to the feet and beaks of birds. Wading
birds, which frequent the muddy edges of ponds, if suddenly flushed, would
be the most likely to have muddy feet. Birds of this order I can show are
the greatest wanderers, and are occasionally found on the most remote and
barren islands in the open ocean; they would not be likely to alight on the
surface of the sea, so that the dirt would not be washed off their feet;
when making land, they would be sure to fly to their natural fresh-water
haunts. I do not believe that botanists are aware how charged the mud of
ponds is with seeds: I have tried several little experiments, but will here
give only the most striking case: I took in February three table-spoonfuls
of mud from three different points, beneath water, on the edge of a little
pond; this mud when dry weighed only 63/4 ounces; I kept it covered up in my
study for six months, pulling up and counting each plant as it grew; the
plants were {387} of many kinds, and were altogether 537 in number; and yet
the viscid mud was all contained in a breakfast cup! Considering these
facts, I think it would be an inexplicable circumstance if water-birds did
not transport the seeds of fresh-water plants to vast distances, and if
consequently the range of these plants was not very great. The same agency
may have come into play with the eggs of some of the smaller fresh-water
animals.

Other and unknown agencies probably have also played a part. I have stated
that fresh-water fish eat some kinds of seeds, though they reject many
other kinds after having swallowed them; even small fish swallow seeds of
moderate size, as of the yellow water-lily and Potamogeton. Herons and
other birds, century after century, have gone on daily devouring fish; they
then take flight and go to other waters, or are blown across the sea; and
we have seen that seeds retain their power of germination, when rejected in
pellets or in excrement, many hours afterwards. When I saw the great size
of the seeds of that fine water-lily, the Nelumbium, and remembered Alph.
de Candolle's remarks on this plant, I thought that its distribution must
remain quite inexplicable; but Audubon