Abstract
The conception that the pathogenic effect of Endamoeba histolytica upon the tissues of man and experimental animals is due to a toxin, or toxins, cytolytic in nature, secreted by the organism, has long been held by students of this interesting and important parasite. However, it must be admitted that no one hitherto has been able to demonstrate experimentally the existence of such toxins in Endamoeba histolytica, the evidence of their presence and activity being based entirely upon the pathology of the lesions produced by the parasite in the tissues of the intestine, liver and other organs of man and experimental animals. The facility with which this parasite may be cultivated upon the media devised by Boeck and Drbohlav (1), Dobell and Laidlaw (2), Craig (3) and others, has rendered it possible to make observations upon the physiology of Endamoeba histolytica and it is the purpose of this contribution to describe the hemolytic, cytolytic and complement-binding properties of extracts of this parasite prepared from cultures of the organism.