Losch (1875) inoculated dogs with dysenteric stools both by mouth and by rectum and was able to produce dysentery in them. At autopsy ulcers containing amebae, similar to those inoculated, were demonstrated in the colon. Kovacs (1892) adopted the intracecal route for inducing amebic infection in cats. Carrera and Faust (1949) demonstrated the high susceptibility of the guinea pig to amebic infection by injecting trophozoites into the terminal ileum after laparotomy. They attempted to detect the progress of the infection by daily examination of freshly passed stool but the findings constituted no dependable index of the severity of infection as determined after death of the animal and consequently they abandoned the examination of feces and had to depend on the autopsy of the animals for the purpose. Rees (1955), in his excellent review on the subject, remarked on the considerable difficulty that may be experienced in ascertaining the prepatent period of rodent hosts because amebae may be multiplying in the cecum and the upper colon without being demonstrable in the fecal pellets.