Preliminary results with a simple method of tissue culture which provides a continuous gradient in cell number, oxygen tension, oxidation-reduction potential, and cell conditioning factors are described and pictured. Cells may readily be examined in in situ at any desired interval with any stain, or by phase microscopy in the living state. The method has proved far superior to any method hitherto tried for cultures of hemic cells of the blood and blood-forming organs. Many possible applications and variations are suggested on this simple procedure of inserting a sterile standard slide at a 45 ° angle into a deep suspension culture in a 1-pint wide mouth French square bottle and allowing the cells to settle out on the surface.