Mitosis
the phenomena of indirect nuclear division of the cells that are growing, or undergoing the changes in the egg which result in the development of the embryo. The first processes are marked by a rearrangement of the nuclear network into a series of loops on V-shaped bodies. During these changes a minute body in the cytoplasm divides in half, forming two cells at opposite poles, the nucleus between. Each consists of a centrosome with a radiating mass. The chromosomes of the nucleus are arranged with ends opening outward and closed ends near the center, and they divide along the contact plane, half joining and being incorporated with each centrosome. As the cell is contracted between the centrosomes a new nucleus is developed in each of the two portions by a process practically the reverse of that just given. The result is the formation of daughter cells, from the mother cell, each containing half of the chromatin elements of equal weight and quality. Chromatin particles are generally believed to be the carriers of heredity.
MITRAILLEUSE (mē-trā-yuhz'), originally the French term for a weapon designed to fire a number of cartridges in a short time, but now used generally for all machine guns. A Belgian invention, it was first used on a large scale in the Franco-Prussian War of 1870. The weapon consisted of a group of combined rifle barrels with breech-action mechanism. The cartridges in steel blocks, were successively dropped into a breech slot, and replaced on discharge by a fresh plate. See MACHINE GUN.