No abstract

No abstract

No abstract

No abstract

The growing interest in the study of the chemical composition of cellular formed elements has led to wide-spread research on techniques for demonstrating and estimating, in situ, the presence and amounts of the various components found by macrochemical analysis. In short, this would involve the use of a quantitive chemical reaction and a means of accurately measuring the end-product of the reaction. Such techniques for measuring nucleoproteins of cell nuclei were recently described by Pollister and Ris.1 Using these same methods, a study of the nature of the Feulgen nucleal reaction was undertaken.The Feulgen reaction may be considered as occurring in two steps: first, the splitting of the linkage between the purine bases and the desoxypentose of the nucleic acid by means of mild acid hydrolysis, and second, a chemical reaction between the aldehyde groups, thus formed on the sugar, and the Schiff reagent (decolorized fuchsin) resulting in the synthesis of a new dye compound. It was noticed by Bauer,2 and confirmed by Hillary,3 that the intensity of color produced in chromatin of cell nuclei is related to hydrolysis in such a way that as time of hydrolysis is increased there is a more and more intense staining until a maximum point is reached; while beyond this maximum, longer hydrolysis results in a decreased staining. The increased staining could easily be explained by the progressive splitting off of bases, as a consequence of which more and more sugar aldehydes are made available for the reaction, which would lead one to expect a maximum when all the purine-desoxyribose linkages have been broken. But the decrease in color after the maximum intensity of stain is reached is quite unexpected. Bauer offered two possible explanations for the latter phenomenon: first, it might be due to a continued decomposition of that part of the nucleic acid molecule remaining after the purine bases have been split off; or second, it