EPITOME  .

EPODE so that movement over the surface is greatly facilitated . Thus the abdominal organs can glide easily over one another within the peritoneal cavity; the blood or lymph experiences the least amount of friction; or again the friction is reduced to a minimum between a tendon and its sheath or in the joint cavities . The cells forming these membranes also possess further physiological properties . Thus it is most probable that they play an active part in the blood FIG . 13 . — Endothelial capillaries in transmitting substances Cells from the Interior of from the blood into the tissue spaces an Artery . or conversely in preventing the passage of materials from blood to tissue space or from tissue space to blood . Hence the fluid of the blood and that of the tissue space need not be of the same chemical composition . (T . G .