In ``The Tenth Book of Their Adventures,'' Henry realizes that Mudge has never been taught such commands as ``sit'' and ``heel.'' With the help of a patient teacher, home practice, and innumerable ``liver treats,'' the huge dog does learn to ``stay,'' at least long enough to pass his training course— though Mudge's forte is clearly being lovable rather than obedient. Not the best in this grand series, but still a fine story for beginners, with appealing characters, lifelike situations, and charmingly comical illustrations. (Easy reader. 5-8)