This book had its origins in some conversations held several years ago. It was felt that a monograph on the subject of tissue specificity might have some merit and interest for a number of scientific workers in the relevant disciplines. Writing was begun slowly, with interruptions; more recently, there has been much more activity, and the relevant literature has been searched and cited up to early 1973. This book was never intended as an exhaustive coverage of all possible topics related to tissue specificity. The tissues and organs covered in six chapters constitute a selected group,...