Two recent meetings of the New York Academy of Sciences (Scanning Techniques in Biology and Medicine, and Applications and Methods of Counting and Sizing in Medicine and Biology) give a good indication of what promises to become a major area of research in microscopy. No longer satisfied with their classical preoccupation with the quality of images, microscopists are now turning their attention to the meaning or content of images. Devices which count, measure, or recognize microscopic objects are a challenge to the imagination, offer a solution to the drudgery and inaccuracy of older methods, and may eventually supply a perceptiveness which surpasses human abilities. The first efforts in this field have typically involved highly specialized equipment, designed and constructed to perform a particular task. As Tolles and Mansberg recently emphasized, there are many advantages to replacing this "one method-one instrument" approach with a combination of scanning microscopy and analysis by digital computer. If one can store the relevant optical information from an object in the memory of a digital computer, the equivalent of a wide variety of special-purpose devices can be accomplished by logical manipulations of the data. Special-purpose computer programs replace special-purpose machines, and one appropriate input device to the computer is the only hardware that need be constructed. As new problems appear or new analytical methods are devised, they can be rapidly and inexpensively tested. Methods attempting to solve similar problems can be compared directly, and most importantly, it is conceivable that batteries of independent methods can be combined to provide powerful analytical tools otherwise not available. A general-purpose device which introduces information from microscopic images into the memory of a digital computer is currently under development at Airborne Instruments Laboratory. Over the past year, tests and reevaluations of this instrument have led to many modifications which are still in the process of being completed. Many of these details and the specifications of the system have been described (Bostrom & Holcomb) and need only be men-