Blastocystis is a cell occurring in the feces and intestine of man and other animals about which considerable confusion has existed for a number of years. It is very often associated with intestinal protozoa and has been described in relation to one or another as a stage of encystment or degeneration by several parasitologists.
In 1915, the writer obtained the cell in culture in ascitic fluid but at the time confused it with a trichomonas cyst. Later, after recognizing it as the Blastocystis of Alexieff (1911), report was made of its prevalence and some of its characteristics in the intestinal content and feces in South Carolina (Lynch, 1917). Following a personal communication in November, 1919, with Dr. H. P. Barrett of Charlotte, North Carolina, in which it was learned that he had obtained blastocystis in culture in liquid human blood serum, further cultivation was attempted with some rather interesting results concerning the nature of the organism and its manner of reproduction.