[Illustration: FIG. 61.--_Xyphorhynchus firmus_ with epimerite in intestinal epithelial cell of host. (After Léger.)] The ectoplasm of a gregarine exhibits three layers: (1) An epicyte (cuticle) externally of which the epimerite is composed; (2) a sarcocyte which forms the septa if present; (3) the deeper myocyte layer containing contractile elements in the form of fibrils or threads termed myonemes (fig. 62). [Illustration: FIG. 62.--_Gregarina munieri_ (from the beetle, _Chrysomela hæmoptera_). Section through surface layers. _Cu_, cuticle; _E_, ectoplasm proper; _G_, gelatinous layer; _My_, myonemes in myocyte layer. × 1500. (After Schewiakoff.)] The endoplasm is fluid and granular, containing many enclosures, which are of the nature of reserve food materials. They consist of fat droplets or of paraglycogen, and give the organisms an opaque appearance. _Lithocystis_ contains crystals of calcium oxalate in its endoplasm. Many gregarines are capable of active movements, though they do not possess obvious locomotor organs. The movement is of a smooth, gliding character and two suggestions have been put forward to explain it. According to Schewiakoff, a gelatinous substance is secreted between the layers of the ectoplasm. This is extruded posteriorly and thus the animal is pushed forward. On the other hand, Crawley considers that the movements are produced by contractions of the myonemes. These two explanations are probably correct as far as each goes, and are to be regarded as supplementary to one another. [Illustration: FIG. 63.--_Monocystis agilis_. Spores from vesicula seminalis of the Earthworm. _a_, Sporoblast with single nucleus, enclosed in sporocyst; _b_, mature spore containing sporozoites; _c_, diagrammatic cross-section of spore, showing eight sporozoites round residual protoplasm. (After Bütschli.)] Occasionally, temporary associations of gregarines are formed by a number of individuals adhering to one another end to end. Such temporary associations are examples of syzygy. Such syzygies must not be confused with true associations which form an essential part of the life-cycle.