A Remarkable Parallelism

4 This resolves itself, of course, into the relative stimulation of different parts of the retina (Sumner, Biol. Bull., 65, 266-282 (1933)). 6 The Ives tint-photometer and Weston foot-candle meter were used for these determinations, which cannot be regarded as more than rather rough approximations. 6 We owe to Professor Eric Ogden, of the University of California, the suggestion which led us to adopt this procedure. 7 The Ives tint-photometer was used for this purpose. (See Sumner, Jour. Mammalogy, 8, 177-206 (1927); Sumner and Fox, Jour. Exp. Zool., 66, 263-301 (1933)). 8 The presence of values greater than 100 is due to the fact that the "black" figures in the table are based upon samples which were not identical with those which were used as our standard. 9 The corresponding ratio of dark gray and black would be impossible to state, since the albedo of the latter is not exactly known (cf. p. 213). If a value of 1 be assumed, the ratio would be 5.9 to 1. 10 Small also in comparison with the effects earlier observed in Lebistes. (Sumner and Wells, Jour. Exp. Zool., 64, 377-403 (1933). 11 Biol. Bull., 70, 8-15 (1936). 12 C. R. Soc. biol., 108, 774 (1931).