Life History.

The galls containing these worms are sown with the seed corn, or are carried by some means into the fields. Upon being moistened either by rain, or the natural dampness of the earth, they become active and penetrate into the stems of the corn plants. They were formerly supposed to permeate the tissues of the plants, as the worms of the Trichinæ permeate the flesh of animals; but it is held by Davaine, Bastian, and others, that the worms ascend with the growth of the plants to the flowers. Mr. Carruthers believes that the worms attack the flowers before their development is perfect, and suggests that, as in other cases, the gall is a simple excrescence caused by the abnormal flow of sap, probably to heal the injury occasioned to the plant.

After the gall is formed, and is yet soft or green, the worms within it pair, and eggs are laid in strings of five and six together, and worms are hatched from these. When the gall in course of time becomes harder, or ripe, no more eggs are laid, and when it is quite hard and dry, the worms are apparently lifeless. Upon moisture being applied they begin to show signs of vitality and wriggle about. They retain vitality for a long time when the galls are kept dry: Taschenberg says for many years. He also shows that they may be exposed to a heat of 123 degrees Fahr. without being affected. It is well known that the hardest frosts do not destroy them. They will also live for months in water. Those who wish to study the history of these and other Nematoids are referred to Bauer's descriptions, illustrated by most elaborate drawings, in the Department of Botany, British Museum, Natural History; and Dr. Bastian's paper on the Anguillulidæ, in part 2 of the Transactions of the Linnean Society for 1865, gives admirable accounts and figures of them.