In 1976 I wrote a monograph on lysosomes (Lysosomes: A Survey, Springer Verlag, Vienna) that was intended as an up-to-date, comprehensive survey. Whatever success I may have achieved then in fulfilling that intention, even the effort now would be foolhardy. The literature has grown so rapidly in the past decade that I certainly could not even read all of the essential papers, let alone understand and analyze them. My goal here, therefore, is simply to introduce the major features of lysosomes at a level I hope will be useful both to I;ldvanced students and to researchers interested in...