Studies on the Fine Structure of a Gregarine Parasitic in the Gut of the Grasshopper, melanoplus differentialis*

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Abstract
SYNOPSIS. Materials within the endoplasm of both the protomerite and deutomerite may be displaced and stratified by ultracentrifugation. Animals are not killed by this treatment, and in time a redistribution of stratified materials may occur. The electron microscope reveals numerous ultramicroscopic folds in the surface envelope which is composed of 3 membranes; the outer and middle cover the surface of the folds while the inner one continues as a smooth membrane over the ectoplasm. The contact surfaces of animals in syzygy do not show the small folds to be interlocked; instead, they are in fold‐to‐fold contact. Numerous relatively dense bodies which appear to be filamentous are sometimes observed immediately underneath or within the middle or inner membrane. Within the ectoplasm is an ultramicroscopic net‐like fibrillar structure much denser than the surrounding cytoplasm. This system of fibrils is composed of anastomosing elements varying from ∼ 50 to 200 Å in diameter. Certain of the larger fibrils are directly attached to the surface envelope at positions between the folds. A second filamentous structure within the ectoplasm appears to be tubular. Elements of this system also appear to join and penetrate the surface envelope by means of pores.A large amount of gelatinous secretion forms at the surface of the sporont; as it glides forward a trail of mucous is left behind. The actual mechanism involved in the gliding movement was unobserved, but evidence is lacking to support the view that the gliding movement is engendered by posteriorly directed “jets” of mucus.