Another aquatic worm, Myrianida, is still more remarkable, not only on account of its eyes, but also on account of the wonderful way in which it reproduces its young. When seen swimming in the water it presents the appearance of a long, many-ringed worm, which impels itself through and by the aid of its hundreds of flat, oar-like legs. Closer inspection reveals the startling fact that this seemingly single worm is really a multiple worm--six or more individuals being joined together, thus forming a living chain. This creature reproduces itself by fissigemation; that is, when the young worms arrive at a certain age they separate from the parent worm and begin life as individuals. These in turn eventually become multiple worms and divide into individuals, and so on _ad infinitum_. The tail worm, or that section farthest from the head, is the oldest and is always the first to leave its comrades and take up a separate existence. The adverb _always_ in the above sentence is, strictly speaking, not exactly accurate, for on one occasion I saw the separation occur at the second head from the tail, thus producing twins. The two sections came apart, however, in a very few seconds after their departure from the colony. I am inclined to believe that this deviation from the normal was due to accident; probably to manipulation. This annelid is really "many in one" until the very moment of division; the alimentary canal, nerves, blood-vessels, etc., extend in unbroken continuity from the head of the parent worm to the tail of the last section. In every fourth (sometimes fifth) ring two round, dark-colored spots will be observed; these spots are ocelli, and some of them eventually become the eyes of young worms. These organs even in their embryonic state possess sight, for they have special nerves and pigment-cells; they can differentiate between light and darkness.