[The formation of lymph].

Fundamental physical properties of lymph formation are described in connection with the permeability of the terminal vascular system (Ludwig Stahling's hypothesis). In view of the current image of this system, as far as it is derived from the isogravimetric model, this can no longer be considered generally valid. Above all the recent vital microscopic studies clearly show that the venous system is of special importance for lymph formation as it possesses special permeability properties and is enclosed by a system of paravascular interstices. They form a protein pool in the tissue releasing a colloid-osmotic energy for the lymph motion. The lymph is drained away by means of "low resistance pathway" correlated with the elastic fiber system and by slow resistance pathways filled with ground substance to reach the efferent lymphatic vessels via an open communication system.