SYMMETRY OF ORGANS. Throughout the animal kingdom, a symmetry of organs very generally prevails in the two sides of the body. This is the case in man and in all the vertebrate; more perfectly, however, in the external than in the internal organs, the two sides of the body presenting great diversities in the circulating, digestive, and other systems. Even the external organs, although similar on the two sides, are never per fectly so. On the two hands, for example, the veins of the one will be seen to differ from those of the other. In mollusca, the symmetry of the two sides sometimes exists, and is sometimes entirely lost, the one side remaining undeveloped iu the growth -of the animal. In the articulate, the symmetry is in general as perfect as in the ver tebrate, and in the internal structure even more so. In the radiate, the whole type is very different, and a very different kind of symmetry appears, not with reference to two sides, but to the rays into which the body divides.
In the vegetable kingdom, a symmetry is found, more or less perfect, but never com pletely so, between the two sides of leaves, fronds, etc. In flowers, a symmetry appears in the regular distribution of sepals, petals, stamens, etc., around the center of the flower; and even those flowers.which least exhibit it when fully blown, as papilionaceous flowers, possess it in the early stages of the bud as perfectly as others.
SYMONDS„Toux ADDINGTON, 1807-71, b. England; educated at the university of Edinburgh, where he took a medical degree. He was physician to the Bristol general hospital, and lecturer at the Bristol medical school. He published Steep and Dreams (1851); the Principles of Beauty (1857), and Miscellanies (1871).