. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 192 SUMNER AND DOUDOROFF melanin concentration, when based upon the mean of readings with the three filters, was , a figure not far from that shown by the solutions of fish melanin. Here, too, the separate figures, based upon the three filters, ranged from 27 per cent (red) to per cent (blue). Some further optical properties of a melanin solution, both when freshly prepared and after standing in the dark for 12 days, are portrayed in Figure 2. This is based upon readings with a Bausch and Lomb Visual Spectrophotomet
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 192 SUMNER AND DOUDOROFF melanin concentration, when based upon the mean of readings with the three filters, was , a figure not far from that shown by the solutions of fish melanin. Here, too, the separate figures, based upon the three filters, ranged from 27 per cent (red) to per cent (blue). Some further optical properties of a melanin solution, both when freshly prepared and after standing in the dark for 12 days, are portrayed in Figure 2. This is based upon readings with a Bausch and Lomb Visual Spectrophotometer of a solution having the same concentration as the "100 per cent" solution of. 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 63 64 65 66 67 68 69 70 71 72 73 74 FIGURE 2. Curves of transmission of various wave-lengths by "100%" solution of purified melanin (see legend for Figure 1). Lower curve = freshly prepared solution. Upper curve = same solution after 12 days. Abscissas = wave-lengths at lO-m/z intervals; ordinates = percent- ages of transmission in comparison with distilled water. Figure 1. The "curve" of transmission, at least for the freshly prepared solution, turns out to be a nearly straight line, with a practically uniform gradient from blue through red. When a fresh "70 per cent" solution is compared with a 12-day-old solution of the same original strength, we find an increase of 22 per cent in the reading with the red filter, an increase of 41 per cent in the reading with the blue. This might be construed as an increase in transmission toward the blue end of the spectrum. It must be remembered, however, that with increasing dilution, the transmission of the various wave-lengths through a colored solution tends to equalize, and that the least transmitted wave-lengths (in this case blue) will increase much more rapidly than the more transmitted ones (in this case red). In passing from a "70 per cent" to a "5
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
