A jelly-speck has no head, no limbs, no stomach, not even a mouth. It can take in food at any part of its soft body. When it wishes--and apparently even a jelly-speck can _wish_, which at once separates it from inanimate materials--it makes a temporary tentacle or “foot,” by pushing out a slender filament of its own substance through one of the tiny holes in its shell. Whence the name “Rhizopod.” Not all the Foraminifera specks live in the same kind of sheltering skeletons. Some construct delicate domes or many-chambered discs of sand-grains, joined together with enough carbonate-of-lime to act as building-cement. Such skeletons are called “tests,” to distinguish them from “shells” proper. Hardly anything can be more remarkable than the way in which these tests are put together by mere specks of jelly, alive indeed, but without parts, without development, without understanding. How and why they should choose from one place, each the especial materials which go to form its own kind of “test,” is one of the mysteries in Nature for which Science has no explanation. We can but look and marvel. One kind of jelly-speck will use the larger grains of quartz, arranging them, and joining them into a bottle-shaped test or shelter. Another, in the same spot, belonging to a different species, will select tinier grains of the same substance, and will build out of them a rounded sphere, exquisitely modelled, with tiny holes at intervals for the protruding “limbs.” Another, of yet a different species, picks out the minutest of sand-grains and of bits of sponge-spicules, and knits them together, without any cement, into delicate white globes, “like homœopathic globules,” giving to each a single opening. And still another, of again a different species, forms a test of divers compartments, with a tiny doorway leading from each into the next. Behind all these extraordinary constructions lies a MIND. But--_not_ the mind of the jelly-speck! Soft oozes, formed chiefly of Foraminifera and other shells, varying in size from a pin’s head to almost invisible specks--though some few kinds are larger--cover immense reaches of the ocean-bed, extending, it is said, over fifty millions of square miles. Yet they are not found everywhere below the sea. Near to Continents, if they exist they are lost sight of amid the masses of sand and mud carried down from the land. And in the profounder abysses of the ocean they are lacking. This last fact was long a puzzle. If the waters above were swarming with live Foraminifera, the dead shells of which must be ever pouring in a quiet rain to the ocean-bed, why should not the same ooze be found there, as elsewhere? That the waters above, at least in all warmer climates, do swarm thus, is certain. Towards north and south, in colder seas, they rapidly lessen; but in tropical regions, and in warm ocean-streams their numbers are legion. Yet, from depths beyond about two miles, the ooze was not brought up.