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 variegated, in the higher mammalians, these patterns are mainly consisted of such as ones with membraneous process, projection waving like a flag, and tentacle-like process, and the pseudopodial movement also becomes more active. On the other hand, the motility of these cells in the case of birds, especially of the pseudopodial movement in chicken, resembles quite closely to that in dog and is quite active. 4. Numbers of motile cells are about the same in dog and chicken, while in the case of mammalians the number decreases in the descending order of dog, cat, rabbit, rat and mouse. 5. The wandering velocity of these cells is highest in the case of rabbit, but it is not so great in all the cases and no marked wandering can be observable either. 6. In tissue culture phagocytes are transformed into fibroblast-like or histiocyte-like cells, but the stage of transfermation in culture and numbers of transformed cells differ according to different animals.