Inhibition of Carboxylase by Thiazole Pyrophosphate.

ies within the twenty-five square degrees area are fainter than that magnitude. (c) The distribution over the plates has been used to examine the nature of the various systematic errors of discovery and measurement. An error arising from plate tilt is intimated; but there is very little suggestion of error from neglected distance correction (figures 1 and 2). (d) The belt at +43?6 crosses the Milky Way twice, and the results obtained are therefore useful in examining the effect, on the distribution of external galaxies, of interstellar space absorption along the Milky Way. Qualitatively the absorption is clearly shown in the last three columns of table 1. This latitude effect and the magnitude-frequency curves will be more closely studied in a following paper. 1 These PROCEEDINGS, 26, 166-176 (1940); Harvard Reprint 194. 2 Seares, Kapteyn and van Rhijn, Mt. Wilson Obs. Papers, Vol. IV (1930). 3 Harv. Ann., 105, No. 10, 226 (1937).