A METHOD FOR THE PHYSIOLOGICAL STUDY OF TISSUES IN VITRO.

1. A method has been developed which allows the continuous growth of pure strains of fibroblasts, epithelium, and leucocytes in a medium which undergoes but slight spontaneous deterioration. 2. The principle of the method is to leave the tissues undisturbed while the medium is changed. This was realized by special containers allowing the change of the medium without bacterial contamination and by the simultaneous use of a solid and a fluid medium. 3. The curve of growth of pure cultures of fibroblasts and epithelial cells in a nutrient medium is a parabola; in a non-nutrient medium, it is S-shaped and expresses the residual activity of the tissues. Leucocytes invade the culture medium progressively, as do bacteria, but never aggregate in a tissue. 4. The method is used for the study of the morphological and dynamic changes occurring in tissues under the influence of chemical and physical factors.