Page:Popular Science Monthly Volume 53.djvu/306

290 territory; it planted a colony. The coast of Asia Minor was colonized from the Greek mainland and the islands of the archipelago; the whole country would nowadays be annexed by a conquering power as the spoil of a single battle and permanently occupied; but it was successively settled by twelve Ionic and twelve Æolic colonies, each of them independent, with conterminous territories. A Greek colony grew in the same way. Naxos or Syracuse, on the Sicilian coast, might, either of them, have annexed the strip of territory between them; they colonized it. A Greek city, like a hydra, was incapable of expanding beyond a certain point; when that point was reached the mass broke and gave birth to a new city. Greece seems never to have got beyond the city stage of national development. Roman colonies were at first of the same character. They were planted in conquered territory, to hold it for Rome, and had a certain independence; as the intervening space between Rome and the colony was occupied by Roman citizens, the colony became continuous with the city and formed part of an undivided empire. So does every nation advance over its own territory. Each new clearing in the surrounding forest is the seat of a colony. The trapper and fur trader of the early days in North America were continually founding stations ever farther in the interior, which proved the nuclei of fresh settlement. The pioneer squatter of Australia is still moving into untrodden regions. Such colonies are like grasses, which are sown by the wind in a myriad separate plants, but become contiguous and form the carpeted turf. As reproduction is discontinuous growth, colonization is discontinuous expansion.

Growth is everywhere limited by the constitution of the organism; beyond a certain size the mass of cells can not be governed from a common center. The limit attained, the augmentation takes on the form and structure of the parent, and, thinning away at the point of junction, a new individual is launched into space. This is the form of reproduction proper to the lower half of organic creation—to invertebrate animals and the more lowly forms of plants. It is nonsexual, for it is produced neither by sexual individuals nor by separate sexual organs in the same individual, nor by the union of differentiated cells. It takes place in unicellular organisms, like the protozoa, by the rupture of the unit mass of protoplasm. Higher species, like sponges or hydras, protrude buds at any point or all round, which often remain connected with' the parent. Or there may be an outflow at a single point successively repeated. The bud may be of all sizes, but is usually less than the parent; in rare cases it is equally large.

The earliest forms of colonization answer in all respects to asexual reproduction. The Phœnician and Greek cities were units;