Studies on the Culture of Endamoeba histolytica. ∗

Summary and Conclusions

1. A heat-stable (100°C for 4 hours), dialyzable substance has been demonstrated in the protein-free fraction of human serum. This substance is essential to the growth of the NRS strain of E. histolytica in egg white buffer infusion medium containing starch. 2. Partially deproteinized filtrate of human serum diluted in an equal volume of M/15 buffer, with rice starch added, constitutes a simple medium for the propagation of E. histolytica. 3. Rice starch appears to act as a temporary inhibitor to bacterial multiplication in these cultures. Such suppression leads to more satisfactory growth of the amebae present. 4. Study of the biology of the bacteria in these cultures may give further information concerning the complex metabolic requirements of E. histolytica.