RADIATION AND ANTHOCYANIN PIGMENTS 1117 



formation of pigment is in many cases not clearly understood. In some 

 isolated plant organs such as the apple and lily-bulb scales the formation 

 of pigment has been shown to depend upon light of a certain quality. 

 In the ]\IcIntosh apple this formation is further known to depend upon a 

 low temperature. From recent contributions to our knowledge of the 

 constitution and synthesis of anthocyanin pigments, it is evident that 

 these are a series of compounds and not a single substance. It is, there- 

 fore, unlikely that the same spectral regions will be found effective in this 

 formation among different plant species. It is certain that the same 

 external conditions do not induce pigment formation in all species, as 

 some tissues form pigment in darkness, others only in light, while still 

 other tissues never form pigment under any conditions. No generaliza- 

 tion can be made that the formation of pigment in plants is related to the 

 accumulation of carbohydrates in tissues. While such an accumulation 

 may be associated with pigment production in a few cases, there is no 

 evidence to show that this is invariably the case or even generally true. 

 It is believed that more progress wall be made in studies under carefully 

 controlled environmental conditions of either whole plants or separate 

 living organs from plants which form pigment. 



REFERENCES 



1. Arthur, John M. Red pigment production in apples by means of artificial light 

 sources. Contrib. Boyce Thompson Inst. 4: 1-18. 1932. 



2. Arthur, John M., and J. M. Newell. The killing of plant tissue and the 

 inactivation of tobacco mosaic virus by ultra-violet radiation. Amer. Jour. 

 Bot. 16: 338-353. 1929. (Also in Contrib. Boyce Thompson Inst. 2 : 143-158. 

 1929.) 



3. AsKENASY, E. Ueber den Einfluss des Lichtes auf die Farbe der Bliithen. Bot. 

 Zeitg. 34: 1-7, 27-31. 1876. 



4. AuBiN, Louis. Vignettes et photographies sur fruits. Revue Hort. 103 : 471- 

 474. 1931. 



5. Beulaygue, L. Influence de I'obscurit^ sur le developpement des fleurs. Compt. 

 Rend. Acad. Sci. [Paris] 132: 720-722. 1901. 



6. Blinks, L. R. Migration of anthocyan pigment in plant cells during the flow of 

 electric current, and reversal by acids and alkalies. Proc. Soc. Exp. Biol, and 

 Med. 29: 1186-1188. 1932. 



7. Bonnier, Gaston. De la variation avec I'altitude des matieres color^s des 

 fleurs chez une meme espece vegetale. Bull. Soc. Bot. France 27: 103-105. 

 1880. (See also Ibid. 35: 436-439. 1888.) 



8. Boyle, R. Experiments and considerations touching colours. London, 1664. 



9. Combes, R. Emigration des substances azot^es des feuilles vers les tiges et les 

 racines des arbres au cours, du jaunnissement automnal. Rev. G6n. Bot. 38: 

 430-448, 510-517, 565-579, 632-645, 673-686. 1926. 



10. Combes, R., and D. Kohler. Ce que deviennent les hydrates de carbone quand 

 meurent les feuilles des arbres. Compt. Rend. Acad. Sci. [Paris] 175: 590-592. 

 1922. 



11. Denny, F. E. Changes in leaves during the period preceding frost. Contrib. 

 Boyce Thompson In.st. 5: 297-312. 1933. 



12. Emerson, R. A. The genetic relations of plant colors in maize. New York 

 [Cornell] Agric. Exp. Sta. Mem. 39. 1921. 



