Gregarines

Gregarines, a sub-class of the Sporozoa (q.v.) containing a series of parasites. The body is rather complex for the Protozoa, it being divided into three segments, an epimerite, a protomerite. and a deutomerite; the last is the largest and most important, as it contains the nucleus (q.v.). All three segments are not always present; when they are the animal is said to be "Cephalont," but when the first is lost it is "Sporont." The body is composed of three layers, an external or "sarcocyte," an internal or "entocyte," and an intermediate fibrillar once known as the "myocyte." There is usually also a cuticle formed from the outermost layer of the sarcocyte. There are two main groups, the Monocystidea and the Polycystidea; the former live in ascidians, worms, etc., while the latter usually infest insects.