known substance. These little shells, which remind us of those of the nautili, are the calcareous envelopes of the animalcules termed foraminifera, which abound in modern seas, and are constantly contributing to the amount of sediment now forming in the bed of the ocean. The beautiful white stone called calcaire grossier, which furnishes the inhabitants of Paris with a cheap and inexhaustible supply of building material, has almost the same structure as chalk; and Professor Ansted has observed that the capital of France, as well as the towns and villages of the neighbouring departments, are almost entirely built of foraminifera.
These stupendous results produced by the agency of creatures that are separately invisible to the naked eye, direct our thoughts to the Creator who has thought fit to endow these living atoms with powers that render them such important instruments in effecting the changes in the earth's surface, which His infinite wisdom has planned.
Let us quit the infusoria and glance with our microscopic eye at some other marvellous objects belonging to the invisible world. If we look through our magic tube at the downy mould formed upon any decaying substance, a wonderful forest of delicate thread-like plants will be revealed. These beautiful fungi will be seen to multiply and grow, to swell and finally to burst, scattering their invisible spores into the surrounding air.
If we make use of our microscope to examine the
