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SUMMARY A semi‐automated system has been developed for the measurement of cell (perikaryal), nuclear and nucleolar areas. The system consists essentially of a Graf/Pen data tablet (with its associated acoustical stylus and tablet electronics), an optical input system such as a camera lucida, and a small digital computer. The perikaryal, nuclear and nucleolar outlines are traced in sequence with the stylus which, on contacting the tablet surface, emits a high frequency acoustic wave that is sensed by X and Y strip microphones along the left and upper edges of the tablet. The acoustic signal is converted by a simple program into a series of X and Y coordinates which are sampled at several points around the perimeter of the profile. When the stylus tip re‐enters a 1 mm stationary window set up around the starting point, the measurement is automatically terminated and the data for this profile is printed out and stored in memory for subsequent statistical analysis. The system has an overall accuracy of about 1% and in practice it has been possible to measure objects at least ten times more rapidly than by any of the other currently available methods. The hardware and software features of the system are detailed and a number of additional uses for the system are described.
Cowan et al. (Sat,) studied this question.