DESMIDIEE, according to the prevalent opinion of naturalists, a tribe or group of slice, and as such ranked by sonic botanists among diatomacece (q.v.); whilst other naturalists regard them as belonging to the animal rather than to the vegetable king dom, some also esteeming them to be vegetable who maintain the animal character of the true diatomacece. They are amongst those lowest organisms which seem to connect the animal and vegetable kingdoms at their common starting-point. The D. are readily distinguished from the true diatomacue by their rounded, not angular form, and by their want of silicious covering; also by their color, which is a her baceous green, whilst the diatomacea are generally brownish. Unlike the diatomacea, they shrivel up, and lose their form in drying. They are, like them, microscopic, but are usually found in stagnant or very slowly running water, sometimes in brack ish, but never in salt water. They may often be procured in great numbers, by
pouring the water in which they exist upon a cloth ; and if the cloth is kept moist, they will live for a long time, and their progress may be observed. They all exhibit a transverse constriction, sometimes not very distinct, but often almost dividing the single cell which forms the organism into two parts. It is at this constriction that new cells are formed; but this process ceases after a while, and a true reproduction takes place by spores, either through conjugation (q.v.) or swarming (q.v.). It is very much on account of these modes of reproduction, and of the presence of starch in the P., that they are confidently referred by naturalists to the vegetable kingdom. Our knowledge of the D. has been much extended by the work of Mr. Baits on the British Dcsnzadieir.