The effects of medicaments, used in the treatment of arthritic diseases, on the surface tension of the synovial fluid have been measured. The synovial fluid was obtained from the carpal joints of freshly slaughtered 'calves and from knee joints of arthritic patients. Values obtained for the surface tension (~) of the pure liquids were 47. 6 mN/m and 45. 8 mN/m respectively. The surfGBPce tensions of the additives and their effect,as a function of concentration, on the surface tension of synovial fluid are shown in figure 2. From this diagram it can be seen that bone and cartilage extract(K u. K-Extrakt) is the most passive additive. The D-Glu- coseamine sulphate preparations cause protein be deposited from the syno- vial fluid. This due to the high acidity of these preparations and the effect disappears when they are buffered at pH 6. With Glycosaminoglycane polysulfate the increase of surface tension with concentration is lower than expected in the case of human synovial fluid. This point shill re- quires clarification. x. Bewegungsformen von Gelenken/Types of Joint Movement PRESSURES WITHIN THE HUMAN KNEE: THE CHANGES DURING QUADRICEPS CONTRACTION IN NORMAL AND DISEASED JOINTS Malcolm I. V. Jayson INTRODUCTION Joint disease affects the use of a joint. Conversely, the use of the joint modifies the joint disease. The first proposition is self- evident, the latter less so.