Pure cultures of parasitic amebas on brain-streaked agar

This work was begun with the attempt to obtain cultures of bacteria-free amebas in crushed rabies brains, the idea being either that the amebas might take up the rabies organisms as food or that they might free the rabies organisms from their host cells and thus bring about, in some way, a culture of the latter, as Clegg reports having done with the B. leprœ.

Four cultures of amebas were selected for a first trial, 3, presumably parasitic (type, Entameba coli), the fourth, a saprophyte (Ameba lirnax). Of these four, only one, a culture from a case of human amebic dysentery, grew with comparative ease and some abundance on agar plates streaked with rabies brains.

I then tried normal brains as controls and found that this strain of ameba grew with almost equal ease on them; so that the problem was changed for the time from that of a possible aid in determining the nature of the Negri bodies to that of the growth of pure cultures of amebas.

Only four investigators (Kartulis 1893, Casagrandi & Barbagallo 1897, Tsugitani 1898) have claimed to obtain amebas growing free from other living organisms and none of these have been quite clear in regard to their technic nor have they apparently grown their organisms for more than two or three culture generations, which, as controls show, does not rule out the factor of subsistence upon food stored up in the amebas themselves.