1. Adam Hilger, Ltd. London, England. Nutting colorimeter.
2. -----. Spekker photoelectric absorptiometer.
3. Albers V. M., andKnorr, H. V. The absorption spectra of solutions of pure chlorophyll and of chloroplasts in living cells. Science85: 51–52. 1937.
4. ————— Absorption spectra of single chloroplasts in living cells in the region from 664 mµ to 704 mµ. Pl. Physiol.12: 833–843. 1937.
5. —————, ————— Fluorescence of the chlorophyll series: The reversible reduction of chlorophylla andb. Physiol. Rev.47: 198. 1935.