. Protozoo?logy. Protozoa; Protozoa, Pathogenic. THE GENERA HERPETOMONAS AND CRITHIDIA 241 Patton finds no evidence of encystment and no evidence of infection of the bedbugs otlier than from human victims. Nor is there any evidence to support the idea of direct inheritance from female bugs to their offspring, but Patton suggests in a later paper (1908) that nymphs of blood-sucking forms of such bugs may take in the infection with their food. The method of reentry into a human host is likewise unknown. B. The Genus Crithidia, Leger, 1902.—The genus crithidia, by reason of its non-kinetic prolon
. Protozoo?logy. Protozoa; Protozoa, Pathogenic. THE GENERA HERPETOMONAS AND CRITHIDIA 241 Patton finds no evidence of encystment and no evidence of infection of the bedbugs otlier than from human victims. Nor is there any evidence to support the idea of direct inheritance from female bugs to their offspring, but Patton suggests in a later paper (1908) that nymphs of blood-sucking forms of such bugs may take in the infection with their food. The method of reentry into a human host is likewise unknown. B. The Genus Crithidia, Leger, 1902.—The genus crithidia, by reason of its non-kinetic prolongation of protoplasm at the base of the flagellum, forms an interesting link in the evolution of the trypano- somes. It is Cjuite true, as Novy, MacNeal, and Torrey ('07) point out, that the distinctions between these several genera are extremely "fragile," and that the points of difference are so minute as not to Fig. 95. Crithidia melophagia, Flu, from the gut of Melophagus ovinus. (After Flu.) A, fully developed parasite with myonenies; B, individual with degenerated trophonucleus; C, encysted fonii (see herpetomonas); D, division form. count for much. It must not be overlooked, however, that minute differences must be utilized in connection with organisms that are themselves minute, and a definite structural feature which Liihe points out as the most characteristic of the genus crithidia, since it exists in all of the parasites regardless of their size, is a perfectly satisfactory differential characteristic, and unlike Leger's original basis of distinction (smaller size of crithidia and truncated ends), has morphological value. The type species is Crithidia subulata, Leger, a parasite of the intestinal tract of a tabanid fly. The body is elongate and slender and drawn out upon the base of the flagellum in a typical manner (Fig. 93, p. 235). The nucleus and blepharoplast are distinct and persistent after 16. Please note that these images are extracted from scann
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