EXPERIMENTAL STUDIES ON ENTAMOEBA: I. TEMPERATURE: A MICROCLIMATIC FACTOR IN THE CULTIVATION OF THREE SPECIES OF ENTAMOEBA

Abstract

By serial transfers at progressively increasing or decreasing temperatures, polyxenic substrains of E. terrapinae, E. invadens, and E. moshkovskii were established at 13 temperatures ranging from 5 to 36.5 °C and maintained there from 51 to 694 days. At constant extraoptimal temperatures (33–36.5 and 15–5 °C), amoebae were at first fewer, larger, and less active than at optimum; cysts were also larger. After adaptation, numbers and average sizes tended to be nearly as at optimum. Preadaptation and (or) adaptation permitted serial cultivation at wider temperature ranges than had been reported by other authors. The following points are also discussed: (a) advantages to E. terrapinae of growth at 5 °C, (b) taxonomic significance of marked difference in lower critical temperatures of E. invadens (12.5 °C) and E. terrapinae (5 °C), (c) previously unreported temporary cyst formation in these reptilian species, (d) tendency of trophozoites to become rounded or sluggish, (e) possible explanation of abnormal size.