Having presumably exhausted all systems the Silversteins now turn to the less interesting subject of skin and related tissue. The basics on skin -- its layers, functions, coloring as determined by melanocytes, skin senses -- are treated in somewhat less detail than might be expected; then, rather than stretch the subject too thin the authors pad it out with material on hair and nails, linings (of stomach, blood vessels, nose), and (following Silverstein formula) the integuments of different organisms from the amoeba on. The brief section on ""frontiers of skin research,"" almost totally concerned with grafting, is disappointing in comparison with parallel material in the systems books. One feels that the Silversteins might have tried harder with this one; but it is a serviceable once-over that covers the subject.