. The biology of the Protozoa. Protozoa; Protozoa. 246 BIOLOGY OF THE PROTOZOA from tlieir capsules, or introduced naked into the blood by some intermediate host. They make their way to the definitive site of parasitism, penetrate into cells and begin their development. In the simpler gregarines only the young stages are passed in such host cells and growth is not accompanied by any marked structural differentiations. In the polycystid gregarines the parasite never becomes entirely detached from its host cell until it is fully mature and de-differentiation begun by the loss of the attaching or
. The biology of the Protozoa. Protozoa; Protozoa. 246 BIOLOGY OF THE PROTOZOA from tlieir capsules, or introduced naked into the blood by some intermediate host. They make their way to the definitive site of parasitism, penetrate into cells and begin their development. In the simpler gregarines only the young stages are passed in such host cells and growth is not accompanied by any marked structural differentiations. In the polycystid gregarines the parasite never becomes entirely detached from its host cell until it is fully mature and de-differentiation begun by the loss of the attaching organ (epimerite). With its growth the body becomes differentiated into an anterior chamber (protomerite) and a nucleus-holding posterior chamber (deutomerite) and in the different species these three portions of the cell become variously ornamented and specialized. The epimerite particularly becomes modified in different ways that are useful for purposes of anchorage. It may be a mere ball of. Fig. 122.— Development of a polycystid grcgarine (schematic). (After Wasielewsky.) protoplasm as in Gregarina longa; a spade-shaped structure as in Pileocephalus herri; a long knobbed proboscis either simple or pro- vided with spines as in Stylorhi/iirhus lougicollis or Geniorhi/uchus monnieri; or there may be many finger-form processes as in Echino- viera hisjnda or thread-like processes as in Pterocephalus giardi. In CoryceUa annata it becomes a single crown of hooks; in Beloides firmiis hooks combined with a lone spine. While these epimerites serve primarily for attachment, they also serve, in some cases at least, as food-getting organs which they take at the expense of the host. In moehiuszi the epimerite forms a long haustoria-like process which extends through the epithelial cell of the gut and into the blood lacunie of the submucosa (Fig. 93, p. 190) and in Htylorhynclnis longicollis a canal is said to extend from the tip of the epimerite through the primite and into the
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