No abstract

The morphology and life cycle of an amoeba producing amoebiasis in reptiles is described. The organism is assigned to the species Entamoeba invadens Rodham 1934, because of the pathogenicity of that species.Material for the study was derived from 30 individuals of 7 species of reptiles, either dying of spontaneous amoebiasis or experimentally infected. (Material from 3 additional species of reptiles dying of amoebiasis was not used in this study.)With the exception of a few minor morphological differences, E. invadens was found to be strikingly similar to E. histolytica in morphology of trophic and cystic stages, and in the processes of encystation, excystation, and metacystic development.Metacystic development was studied in stained preparations made from the intestines of snakes 1–24 hours after the inoculation by mouth of mature cysts. Excystation usually takes place in the jejunum and ileum, a single quadrinucleate amoeba hatching from each cyst. Each quadrinucleate metacystic amoeba ultimately forms 8 amoebulae as a result of one division of each cystic nucleus, cytoplasmic division, and parcelling out of the cystic (N) and daughter (n) nuclei. Nineteen of the 24 possible combinations of N and n nuclei were observed.The culture phenomena of multiple fission without encystment is suggested, and cannibalism of cysts by the trophozoites is described.

From 1901 through 1932 arteriosclerosis was found in less than 3 per cent of autopsies on mammals and birds at the Philadelphia Zoological Garden, but thereafter its frequency has increased to about 20 per cent. This study has attempted to identify factors that may be associated with this change in frequency.