. The biology of the protozoa. Protozoa; Protozoa. 202 BIOLOGY OF THE PROTOZOA sites suggest the peculiar relation which Shibata (1902) has described in the intracellular mycorhiza, where a mycelium thread is grown straight toward the nourishing cell nucleus of the host, causing marked hypertrophy on the part of the cell. In Caryotropha, the nucleus of the host cell is pushed to one side and the parasite assumes such a form that the nucleus lies in a small bay (Fig. 103, 2n). In the cytoplasm of the cell an intranuclear canal is then formed which runs from the host nucleus to the nucleus of th
. The biology of the protozoa. Protozoa; Protozoa. 202 BIOLOGY OF THE PROTOZOA sites suggest the peculiar relation which Shibata (1902) has described in the intracellular mycorhiza, where a mycelium thread is grown straight toward the nourishing cell nucleus of the host, causing marked hypertrophy on the part of the cell. In Caryotropha, the nucleus of the host cell is pushed to one side and the parasite assumes such a form that the nucleus lies in a small bay (Fig. 103, 2n). In the cytoplasm of the cell an intranuclear canal is then formed which runs from the host nucleus to the nucleus of the para- site, and Siedlecki holds that the food of the parasite is all elab- orated by the nucleus of the host cell, while the other spermatogonia form a protective epithelial sheath around it. When the parasite is full grown the cell is destroyed and the bundle _ O. Fig. 104.—Ellobiophrya donacis, a peritrich with ring-form attaching organ which passes around the gill bars of the lamellibranch. X 800 and 1350. (After Chatton and Lwoff, Bull. biol. de la France et de la Belgique, 1929; courtesy of Prof. N. Caullery and Les presses TJniversitaires de France.) Other special adaptations in the interest of food-getting are fre- quently spectacular. Thus Ellobiophrya branchiorum (Chatton and Lwoff, 1928), a commensal ciliate on the gills of the lamellibranch Donax sp., has developed a curious, posterior, ring-form process whereby it is firmly anchored to the gill bars (Fig. 104). It is difficult to draw the line between symbionts, commensals and parasites. Symbionts are organisms living with a host in such a relation that both are benefited; commensals are organisms which live with a host without benefit or injury to the latter but to their own advantage, and parasites are organisms which, to their own benefit, cause injury in one form or other to the host. Symbiosis. Please note that these images are extracted from scanned page images that may have been digitally en
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