3° 



PHYSIOLOGY OF NUTRITION 



decreasing in intensity and ceasing not far beyond the D line. Thus starch 

 is produced by those wave-lengths of light that cause the decomposition of 

 carbon dioxide, the rays between B and C being most effective in both cases. 



Briosi 1 was unable to find starch in the leaves of Musa (banana) and Strelitzia, 

 but found oil instead, and expressed the opinion that the latter was the first 

 product of photosynthesis in these plants. Holle 2 and Godlewski 3 were able 

 to prove, however, that this supposition is untenable. 



Baeyer 4 advanced the hypothesis that formaldehyde is really the first prod- 

 uct of photosynthesis, and that carbohydrates arise from this by progressive 

 condensation or polymerization. The formation of formaldehyde thus supposed 

 is represented by the equation, C0 2 + H 2 = CH 2 + 2 . Baeyer based his 

 supposition upon a discovery by Butlerow 5 that oxymethylene (C3H6O3) is con- 

 verted into a sugar-like substance in the presence of calcium and barium 

 hydroxides. 



Reinke is of the opinion that the hydrate of carbonic acid and not the 

 anhydride, is decomposed in the light, as indicated by the equation, H 2 C0 3 = 

 CH 2 + 2 . The same author 6 was successful in showing that substances 

 possessing aldehyde characters generally occur in green plants, and Curtius and 

 Reinke 7 succeeded in isolating a material of this sort and in identifying it chem- 

 ically. Curtius and Franzen 8 isolated a-/3-hexylene-aldehyde from the leaves of 

 Carpinus (horn-beam). This aldehyde shows the same carbon skeleton as does 

 glucose, as becomes evident from a comparison of their structural formula?: 



•° 



CH 3 — CH 2 — CHo— CH=CH— Cf (a-/3-Hexylene-aldehyde) 



X H 



CHa— CH— CH— CH— CH— Cf (d-glucose). 



I I I H 



OH OH OH OH OH 



Pollacci 9 found, furthermore, that the green parts of plants gave a positive 

 aldehyde reaction with Schiff's reagent only if they had been previously exposed 



1 [Briosi, Giovani, Ueber normale Bildung von Pettartiger Substanz im Chlorophyll. Bot. Zeitg. 31: 



520-533,545-550. 1873.] 



2 Holle, H. G., Ueber die Assimilationsthatigkeit von Strelitzia regina. Flora, n. R. 35 : 1 13-120, 154- 

 160, 161-168, 184-192. 1877. 



s Godlewski, Emil, 1st das Assimilationsprodukt der Musaceen Oel oder Starke? Flora, n. R. 35: 215- 

 220. 1877. 



* Baeyer, Adolf, Ueber die Wasserentziehung und ihre Bedeutung fur das Pflanzenleben und die Gah- 

 rung. Ber. Deutsch. Chem. Ges. 3 : 63-75. 1870. 



6 [Butlerow, A., Bildung einiger Zuckerarten durch Synthese. Liebig's Ann. Chem. u. Pharm. 120: 295- 

 298. 1861. Idem, Formation synthetique d'une substance sucree. Compt. rend. Paris 53 : 145-147- 1861.] 



6 Reinke, J., Studien uber das Protoplasma. I-III. Untersuch. Bot. Lab. Gottingen 2 : 1-202. 1881. 

 Idem, Studien uber das Protoplasma. 2te Folge. Ibid. 3 : 1-76. 1883. 



7 Curtius, Theodor, and Reinke, J., Die fliichtige, reducirende Substanz der grunen Pflanzentheile. Ber. 

 Deutsch. Bot. Ges. 15: 201—210. 1897. 



8 Curtius, Theodor, and Franzen, Hartwig, Aldehyde aus grunen Pflanzenteilen. I. Mitteilung. Ueber 

 a-0-Hexylenaldehyd. Sitzungsber. (math.-naturw. Kl.) Heidelberg. Akad. Wiss. Jahrgang 1910, Abhandl. 

 20. 13 p. 1910. 



9 Pollacci, Gino, Intorno all' assimilazione clorofilliana delle piante. Atti 1st. Bot. Univ. Pavia. //, 

 7: 1-21. 1902. On the synthesis of carbohydrates in chloroplasts see: Fischer, Emil, Synthesen in der 

 Zuckergruppe. II. Ber. Deutsch. Chem. Ges. 27 7// : 3189-3232. 1894- P- 3230. 



