Cultural Amœbæ from the Intestine of Man

I SHOULD like to thank your reviewer for his commendatory remarks in NATURE of December 21, 1916, on the account of the parasitic Protozoa which I contributed to the ``Animal Parasites of Man.'' Without in any way wishing to raise a discussion, I think it should be pointed out, in respect to his statement about Amoeba limax, that much information concerning these cultural organisms that may occur in the human intestine will be found under the designation ``cultural amœbæ'' on pp. 42, 618, 742 and 743 of my work. As your reviewer rightly infers, A. limax is not now strictly the name of a single species, but rather of a group or type of free-living forms which show differences among themselves, but can be cultivated on artificial media. It is not easy to point out marked differential characters between them and Entamœbæ, especially after consideration of the work of Drs. Williams and Calkins, to which reference is made by me on p. 42 and pp. 742 and 743 of the book.