400 500 600 



Wave-length (m/i.) 



Fig. 6.1. Comparison between the density spectra of pike and tench 



extracts, before and after total bleaching by white light. The vertical 



dashed lines facilitate comparison of the two difference spectra. Pike 



extract, pH 8-24; tench extract, pH 8-40; T = 20°C. 



{Dart nail, 1952a) 



