Photographic colorimetry as a quantitative cytochemical method

Summary A method for quantitative cytophotometry based on the photographic method of Ornstein is described. Taking special precautions, photographic negatives are made of microscopic objects with light from the appropriate part of the spectrum. Enlarged prints, developed in a blue colour, are made from these negatives. Stirring with a stream of nitrogen was applied in this procedure.The images of the objects in the blue print are cut out, and the amount of dye proportional to the integrated extinction of the objects is measured in a colorimeter. This method, for which the name photographic colorimetry is proposed, was tested on Feulgen-stained nuclei from various sources. The reproducibility of the method was found to range from 3 to 5%.Submitted in partial fulfillment of the requirements for Ph. D. degree (Den Tonkelaar 1963).