In the vital observations on 19 cases of liver cirrhosis, 4 cases of tuberculous peritonitis, 3 cases of nephrosis, and two cases of cardiac insufficiency by means of tissue culture of ascites of respective group, the auther obtained the following results: 1. In the case of arcites of liver cirrhosis, the average cell count is 219/m㎥, and aside from phagocytes the appearance (average of 2.7%) of phagocytic sigenet-ring cells, a marked increase (average, 9.2%) of serous cells, a slight increase (average, 2.2%) of neutrophils can be recognized. The intermediatesize phagocytes have peculiar grass-like pseudopodia and serous cells have tongue-shaped pseudo-podia that are moving actively. 2. In the case of tuberculous peritonitis, the average cell count is 1, 820/mm3. There can be recognized such charachteristics as a marked increase (average, 51.7%) of small-size phagocytes, an increase (average, 39.9%) of lymphocytes, and the appearance of intermediatesize phagocytes shapedlike sea urchins as well as lymphocytes that move more actively six hours after the start of culture than at the initial stage of culture. 3. In the case of nephrosis an increase of small-size phagocytes and a slight increase of serous cells, but most of cells are degenerated, and also fibroblast-like degenrative intermediate-size phagocytes can be observed. 4. In the case of cardiac insufficiency, a slight increase of neutrophils can be observed, but the most outstanding characteristic in this case is an early degeneration of all cells. 5. As can be seen from the above, in the vital observations each kind of non-tumorous ascites has its own cytological charateristic traits and by these traits it is definitely possible to distinguish tumorous ascites from non-tumorous ones. Therefore, the clinical application of such vital observation offers a great promise in the differential diagnosis of ascites.