As with _T. intestinalis_ so with _C. hominis_, it appears that the parasite settles not only in the intestine but also in the air-passages. This is demonstrated by the statements of Kannenberg and Streng of the occurrence of Monads and Cercomonads in the sputum and putrid expectoration in gangrene of the lungs, which no doubt apply to _C. hominis_ (_cf._ also Artault). Possibly also the Flagellata observed in the pleural exudation by Litten and Roos may be included here; this is the more probable in Roos’s case as the process ensued in the pleura after the breaking through of a vomica. Perroncito and Piccardi have described encysted stages of Cercomonads. *Monas pyophila*, R. Blanch., 1895. [Illustration: FIG. 23.--_Monas pyophila_, R. Blanch. (After Grimm.)] R. Blanchard thus designates a Flagellate that Grimm found in the sputum, as well as in the pus of a pulmonary and hepatic abscess, in the case of a Japanese woman living in Sapporo. The parasites resemble large spermatozoa (fig. 23). The body, 30 µ to 60 µ, has the shape of a heart or a myrtle leaf, and is surrounded by a thick cuticle which is supposed to extend into the interior of the body, dividing it into three parts. A long appendix at the rounded pole is covered for the greater part of its length by the cuticle; the extremity, however, is free and resembles a flagellum. The parasites were very active, frequently changed their shape, and were able to retract the long appendix within the body, which then assumed a round form. [This organism requires further investigation.] Family. *Bodonidæ*, Bütschli. _Protomonadina_ which are either free-living or parasitic, with two dissimilar flagella, while the possession of an undulating membrane and of a kinetic nucleus or blepharoplast is variable. There are three genera:-- 1. _Bodo_, Stein, 1878, without a kinetic nucleus and undulating membrane. 2. _Prowazekia_, Hartmann and Chagas, 1910, with a kinetic nucleus and without an undulating membrane. 3. _Trypanoplasma_, Laveran and Mesnil, 1901, with a kinetic nucleus and undulating membrane. Of these genera _Prowazekia_ must be discussed. _Bodo_ does not occur in man. Species of _Trypanoplasma_ occur in the blood and in the gut of various fishes, in the seminal receptacle of certain snails, in the gut and genitalia of a flatworm (_Dendrocœlum lacteum_) and in the vagina of a leech. Closely allied to _Trypanoplasma_ is the genus _Trypanophis_, parasitic in the cœlenteric cavity of Siphonophores. Genus. *Prowazekia*, Hartmann and Chagas, 1910.