Some of the amoebae (the diatoms, for instance) secrete solid matter from the water, and build therefrom shells or houses, which serve to protect them from their enemies. These shells are full of tiny holes, through which the pseudopods are extended in their search for food, and for purposes of movement. Some of these shells are composed of secreted lime, and others of a flinty substance, the "selection" of these substances from the ether mineral particles in the water, evidencing a degree cf "thought," and mind, even in these lowly creatures. The skeletons of these tiny creatures form vast deposits of chalk and similar substances. Next higher in the scale are the _Infusoria_. These creatures differ from the amoebae inasmuch as instead of pseudopods, they have developed tiny vibrating filaments, or thread-like appendages, which are used for drawing in their prey and for moving about. These filaments are permanent, and are not temporary like the pseudopods of the monera or amoebae--they are the _first signs of permanent hands and feet_. These creatures have also discovered the possibilities of organs and parts, to a still greater degree than have their cousins the amoebae, and have evolved something like a mouth-opening (very rudimentary) and also a short gullet through which they pass their food and oxygen--_they have developed the first signs of a throat, wind-pipe and food-passage_. Next come the family of Sponges, the soft skeletons of which form the useful article of everyday use. There are many forms who weave a home of far more delicacy and beauty than their more familiar and homely brothers. The sponge creature itself is a slimy, soft creature, which fills in the spaces in its spongy skeleton. It is fastened to one spot, and gathers in its food from the water around it (and oxygen as well), by means of numerous whip-like filaments called _cilia_, which flash through the water driving in the food and oxygen to the inner positions of its body. The water thus drawn in, as well as the refuse from the food, is then driven out in the same manner. It is interesting to note that in the organisms of the higher animals, including man, there are numerous _cilia_ performing offices in connection with nutrition, etc. When Nature perfects an instrument, it is very apt to retain it, even in the higher forms, although in the latter its importance may be dwarfed by higher ones.