Blood-worm

Blood-worm, a name given by anglers and others to the very abundant aquatic larva of a gnat-like Dipterous insect known as Chironomus plumosus. This is the commonest of a large number (195) of British species, and the larva is very frequent in stagnant water. It has a worm-like appearance, a blood-red colour, and is used for bait. The development of Chironomus is of great biological interest on account of the very early isolation of those elements which are to form the future reproductive organs of the insect. Before the cells of the dividing egg have had time to change at all, these future reproductive rudiments are set apart, and as they do not share in the future changes of development, they must obviously preserve intact the constitution of the parent, and hand it on to the next offspring. See HEREDITY.