Fig. 52.—Toxoplasma pyrogenes. 1, body found in blood. 2–7, bodies found
in spleen. [1 is about the size of a red blood corpuscle, as drawn in the figures]. Magnification not stated. (After Castellani.)]
Castellani (1913–14)[141] has described similar parasites from a case of splenomegaly, with fever of long standing, in a Sinhalese boy. The bodies were found in the spleen and more rarely in the blood (fig. 52). Castellani has named them Toxoplasma pyrogenes. Further researches are needed.
THE SPIROCHÆTES.
The Spirochætes are long, narrow, wavy, thread-like organisms, with a firm yet flexible outer covering or periplast. There is a diffuse nucleus internally in the form of bars or rodlets of chromatin distributed along the body. In some forms there is a membrane or crista present (fig. 53), which in the past was compared with the undulating membrane of a trypanosome, but the membrane of a spirochæte does not undulate. Progression is very rapid, corkscrew-like and undulatory movements occurring simultaneously.
The genus Spirochæta was founded by Ehrenberg in 1833 for an organism which he discovered in stagnant water in Berlin. Ehrenberg named the organism Spirochæta plicatilis. According to Zuelzer (1912) S. plicatilis does not possess a membrane or crista, but an axial filament. S. gigantea has been described by Warming from sea-water.
Fig. 53.—Spirochæta balbianii. a, basal granule or polar cap. b, chromatin rodlets. c, membrane (“crista”). d, myonemes in membrane. (After Fantham and Porter.)