Manometric studies on the effect of tissue extract upon calcium precipitation.

DURING the course of researches on the influence of calcium upon the anaerobic fermentation of tumour tissue [Lasnitzki & Rosenthal, 1935] an interesting side observation was made. The investigations were carried out by Warburg's method [1926], the calcium being added to the medium after the tissue had fermented for a while in potassiumand calcium-free Ringer's solution. It was found that the calcium remained in solution in relatively high concentration, while under the same conditions, but in absence of tissue, it gradually precipitated as carbonate, carbon dioxide being thereby developed. It is only because of this effect of the tissue that it was possible to investigate the influence of higher concentrations of calcium upon fermentation. Soon it was observed that stabilization of calcium also occurred if the tissue, after 1 hour's shaking in potassiumand calcium-free Ringer's solution, was removed from the medium, and the calcium subsequently added. These findings appeared to be ofparticular interest, in so far as they suggested that the manometric method may be suitable to study in a simple but accurate manner the inhibition of calcium precipitation under physiological conditions by the action of certain substances, especially those contained in animal tissues. From this point of view further investigations have been carried out in a similar way to test whether the observed effect can be obtained with extracts from normal tissue in different dilutions. Before, however, considering the results of these investigations we have to discuss in some detail the application of the manometric method to our subject.