Two years ago the opportunity was presented for the study of a number of monkeys that were carriers of an amoeba indistinguishable from Endamoeba histolytica of man. Since amoebic infections in monkeys are in many respects similar to those in man, the observations to be recorded in the following pages may help to clear up some of the problems yet to be solved on host-parasite relations in human amoebiasis.
Although the pathological anatomy of amoebiasis, both experimental and spontaneous, has been thoroughly investigated in the many hosts which are susceptible, there are still a number of phases in which opinions differ. One of these is whether or not the presence of E. histolytica in the gut is necessarily associated with tissue invasion. Views in favor of the hypothesis that infection is always accompanied by tissue invasion have been expressed by Bartlett (1), Hiyeda and Suzuki (2), Craig (3), and many others.