SYNOPSIS. Thru the application of technics of serology, cultivation in acid and basic media, host specificity and reaction in foreign hosts it became possible to characterize 10 species of Crithidia and to assign names to 5 of those previously undesignated. Despite a loose host specificity under experimental conditions it was found that each isolate from a different insect host was a different species.

No abstract

The occurrence of Babesiosoma stableri n. sp. in the erythrocytes of Rana pipiens pipiens extends the host range of babesiosomids to the Salientia. The proposed sequence of developmental stages includes the following events: (1) two successive nuclear divisions of the uninucleate trophozoite produce a tetranucleate organism, (2) cytoplasmic cleavage initiated at each pole of the tetranucleate parasite results in four daughter individuals arranged in a cross‐form, (3) the four merozoites originating from the cruciform schizont separate without the formation of a residual mass of cytoplasm, (4) gametocytes which presumably arise from differentiated merozoites do not exhibit dimorphism. The morphology and characteristics of the parasite's development were not altered when B. stableri was experimentally transferred to: R. p. sphenocephala, Rana catesbeiana, Bufo americanus, Bufo woodhousei fowleri, and Bufo terrestris. Experimental infections, with few exceptions, exhibited a peak parasitemia followed by a decline in the number of babesiosomids. Infections persisted at a low level or disappeared during the period of study.