Abstract
It has been shown by Shipley 1 and the observation has been confirmed by Shipley, Howland and Kramer 2 that calcification of slices of cartilage and bone from a rickety animal takes place in vitro within 48 hours when the slices are immersed in normal blood serum at 37° C.
In the course of a series of experiments upon calcification from solutions of inorganic salts, we have repeatedly observed that calcification takes place only when the concentrations of blood electrolytes are considerably reduced below the concentrations in the blood serum. When a salt mixture is used approximating as closely as possible the inorganic composition of blood serum, 3 no calcification whatever occurs, even in preparations which have been incubated as long as 10 days. A sample experiment is given in the table. It would therefore seem necessary to postulate the existence in the blood serum of some factor which enables calcification to take place in spite of the high concentration of electrolytes.
It seems altogether improbable that the serum proteins could be concerned in producing this effect, since proteins in general, owing to their ionic nature, would be expected to inhibit rather than to promote calcification. Moreover, the experiments of Shipley, Howland and Kramer have shown that egg albumen and gelatin actually do inhibit the process.
Experiments to determine the nature of this unknown factor are now in progress.
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