In studying American Rhizopods representatives of most European genera are found, and it is seldom, indeed, that a new species is discovered. This wonderfully broad distribution is probably due to their being so exceedingly small that they may be carried from place to place by moving water or air, or in the moisture on the surfaces of aquatic animals, as well as to the fact that the numerous germs, and even adult forms of many, are capable of being dried and wafted, like particles of dust, from one part of the earth to another. Wherever they chance to fall into the water, under favorable conditions, they may revive, live, and multiply.