By performing a series of rabbit bone-marrow tissue culture, the author compared with various plasmas, the fixed position of thin rectangular coverglass which was introduced into the test tube, and various salt solutions; and obtained the following results. 1. When rabbit plasma is used as the plasma clot for this method of tissue culture, the tissue growth rate is greater than that in the case of chicken plasma, but it is apt to cause liquefaction and fusion of the plasma clot and also makes it difficult to observe the cell structure. In contrast to this, with the use of chicken plasma, although the tissue growth rate is lower than in the case of the former, the regressive degeneration of cells is less than the former and the cell structure is maintained distinctly. Therefore, the latter plasma is more suitable for such a tissue culture. 2. As for the position of fixing the thin rectangular coverglass, it is best to fix it in such a way so that the explant placed on the coverglass is at the maximum distance from the inner wall of the testtube, when it is fixed at the minimum distance from the inner wall of the testtube, it gives the worst results; while when the coverglass is not fixed, it gives intermediate results. 3. As for the solutions to be used in the medium, Gey's solution is excellent from the standpoints of the rate of tissue growth, the wandering velocity of pseudoeosinophils and the rate of appearance of regressively degenerated granules for the effectiveness in tissue culture, followed by Hanks's solution, Tyrode's solution, Ringer's solution and physiological saline solution, in the order mentioned. However, no marked differences can be observed among the first three solution.