Biologists are not entirely agreed in which kingdom to place the organisms, although they usually are classified with the plants. They start life as spores, like the dust of molds or toadstools whose single-celled particles serve the same reproductive function as seeds in higher plants. From each spore arises from one to four animal-like organisms, hardly distinguishable from the one-celled protozoan animal, the amoeba. Each swims about freely for a time by means of tentacle-like arms, the flagellae. These free-moving living particles are known as “swarm cells”. Each is an individual with a film-like skin separating it from all other individuals. That is, the protoplasm of each cell is enclosed within a boundary and in the center of each is a nucleus. These one-celled “animals” wander about freely for a few days. During this time they may mate, as individuals. More commonly each loses its flagellae and splits into several fragments. Each of these fragments becomes a complete organism. These mate, with complete fusion of their bodies. The result is a double plant or animal—depending on whether it is observed by a botanist or zoologist—known as a zygote. The fragments are extremely voracious little creatures devouring greedily the one-celled plants, or bacteria, which they encounter. When the fusion is complete the zygote, in turn, starts to split up into single-celled organisms but after a few divisions hundreds of these single-celled animals coalesce into a tiny ball, like the seed pod of a plant. In a few days thousands of these spheroids collect into a so-called “plasmodium”. The hitherto individual pseudo-protozoans meanwhile have lost their cell walls. The primaeval substance of millions is mixed together into a slimy mass full of cell nuclei. This is an aggregation of “naked protoplasm”. It is hardly to be compared with the body of any higher plant or animal where each cell retains something of its individuality, however closely its activities may be coordinated with those of its fellows in the same community. The mass proceeds to behave like a voracious animal. It moves and feeds as a unit and apparently with a purpose. Within the naked protoplasm there is apparently some incomprehensible sense of fellowship which eventually evolves into consciousness and intelligence, developing nerve and brain on the way upwards. It would be hazardous to say that this evolution could have taken no other path. From the central body great numbers of thread-like filaments are sent out to penetrate the substance of rotting wood or the surface of a dead leaf. These threads seem to be like an army’s scouting parties, pushed ahead to locate supplies when advancing troops are living off the country. When a supply is found they are drawn in and the whole slimy organism acts once more as a coordinated whole.