THE QUARTERLY REVIEW OF BIOLOGY 



more complex bodies? Then, in the soil 

 we should expect to find pyrrole com- 

 pounds and other organic compounds 

 which probably are directly of very 

 great value to growing plants. 



Is the story of nitrogen something like 

 this or must we look for a solution of the 

 whole problem at some future date? The 

 problem is too big a one for me to answer, 

 for I have been concerned only with the 

 effect of nitrogen on chlorophyll and 

 know practically nothing regarding the 

 other subjects about which I have written. 



Final proof will be obtained only after 

 much more work is done, and so I leave 

 the phases of the subject other than 

 chlorophyll to those who possess a far 

 greater working knowledge of the sub- 

 jects than I do. All I ask is an earnest 

 individual consideration of the whole 

 problem,— Can chlorophyll be broken 

 down chemically by light to form vita- 

 mines as nature in her great laboratory is 

 undoubtedly doing every day or are we 

 going to keep on trying to find out what 

 vitamines are in some other way? 



LIST OF LITERATURE 



In general, only authors' most recent articles are 

 referred to in this bibliography. These will furnish 

 the reader a key to much in the literature. A com- 

 plete bibliography on chlorophyll, vitamines and the 

 effect of light on chemical compounds would be too 

 lengthy for any paper. In connection with the study 

 of ideas in this paper, references on light, absorption 

 bands and chemical constitution as affected by light 

 should be freely consulted. 



Allison, F. E. Nitrogen as a plant food. Jour. 

 Chem. Ed., 3:50-58. 1916. 



Amar, Jules. Radiations et chlorophylle. Compt. 

 rend. acad. agr. France, 181:1353-1354. 19x6. 



Blackman, V. H. Solar radiation and plant growth. 

 Jour. Min. Agr., 33:816-819. 1916. 



Cady, H. P. and Robert Taft. Oxidation and reduc- 

 tion. Jour. Phys. Chem., 19:1057-1074. 192.5. 



Combes, Raoul. Emigration des substances azotees 

 des feuilles vers tiges et les racines des arbres au 

 cours du jaunissement automnal. Rev. Gen. 

 Bot., 38:631-645. 1916. 



Coward, K. H. The persistence of vitamine A in 

 plant tissues. Biochem. Jour., 19:500-506. 

 192.5. 



Deuber, Carl G. Influence of mineral elements upon 

 development of chloroplast pigments of soy 

 beans. Bot. Gaz., 81:131-153. 192.6. 



Drummond, J. C, H.J. ChannonK. and H. Coward. 

 Studies on the chemical nature of vitamine A. 

 Biochem. Jour., 19:1047-1067. 1915. 



Dubosc, A. La chlorophyll et la lumiere. Moniteur 

 Sci., 16:118-141. 1916. 



Dye, M., O. C. Medlock and J. W. Crist. The 

 association of vitamine A with greenness in 

 plant tissue. — I. The relative vitamine A con- 



tent of head and leaf lettuce. Jour. Biol. Chem., 



74:95-106. 1917. 

 Eckerson, Sophia H. Protein synthesis in plants. I. 



Nitrate reduction. Bot. Gaz., 77:377-390. 



1914. 

 Funk, Casimir. The Vitamines. 1911. 

 Gibson, R. J. Harvey. A photoelectric theory of 



photosynthesis. Ann. Bot., 11:117-110. 1908. 

 Javillier, M., P. Baude and S. Levy-Lajeunesse. 



Essais d 'identification du facteur A. Le facteur 



A et le phytol. Compt. rend., 179:998-1000. 



1914. 

 Lasareff, P. Uber die Absorption des Lichtes dutch 



die Blatter der Pflanzen und die Absorption von 



Chlorophyllosungen. Biochem. Z., 181:131- 



133. 1917. 

 Lubimenko, V. Les pigments des plastes et leur 



transformation dans les tissus vivants de la 



plante. Rev. Gen. de Bot., 40:13^.9. 1918. 

 Mockeridge, Florence A. The formation of plant 



growth-promoting substances by microorganisms. 



Ann. Bot., 38:713-734. 1914. 

 Morhardt, P. E. The chemical constitution of 



vitamines. La Nature. No. 1771. p. 176. 



1917. 

 Noack, Kurt. Photochemische Wirkungen des 



Chlorophylls. Naturwissenschaften, 14:383- 



389. 1916. 

 Oddo, B., and G. Pollacci. Influenza del nucleo 



pirrolico nella formazione della chlorofilla. 



Gaz. chim. Ital., 50:54-70. 1910. 

 Palmer, Leroy S. Carotinoids and Related Pigments. 



316 pp. 1911. 

 Randoin, L., and H. Simonnet. Essai de definition 



des vitamines. Bull. Soc. de Chim. Biol., 7: 



1 010-1013. 1915. 



