In the observations on cells in normal ascites of mammalians (dog, cat, rabbit, rat and mouse) and of birds (chicken, pigeon and rice-bird) in tissue culture, the author obtained the following results: 1. Cells in the ascites of normal animals are consisted of many phagocytes designated commonly by various nomenclatures, and they present such a multiplicity that they may be classified into three types, large, intermediate, and small. 2. The morphology of these phagocytes in mammalians tends to resemble closely to monocytes in blood in the descending order of mouse, rat, rabbit, cat, and dog. That of chicken also resembles monocytes. 3. Although the motility patterns of phagocytes, especially of pseudopodia in the lower mamalians are variega...