Abstract
E. histolytica was cultured with live and heat-treated Trypanosoma cruzi as a substitute for the bacterial associates previously used. Technique is given. The advantage of this combination is that T. cruzi may be inactivated at little over 37[degree]C, and hence without as much deleterious effect on proteins and enzyme systems as occurs in the heat killing of bacteria cultures may thus serve as a basis for the identification of growth factors required by E. histolytica.