250 



INTERMEDIATES IN REDUCTION OF CO2 



CHAP. 10 



Table 10. 1 — Continued 



Compound 



Formula 



Structure 



Re- 

 duc- 

 tion 

 level, 

 L 



Occur- 

 rence in 

 green 

 plants 



d Compounds 



Cs Compounds 



Valeraldehyde 

 Pentenol 



CH3(CH2)3CHO 

 CH3CH2CH=CHCH20H 



1.40 

 1.40 



*(22) 

 *(23) 



Ce Compounds 



Many of the asterisks in table 10. 1 refer to occasional, qualitative observations. 

 The unreliabihty of such data can be judged from the critical reviews by Franzen and 

 Stern (1921), who found that only four out of several hundreds of analyses purporting 

 to prove the presence of lactic acid in plants were reliable, and by Franzen and Keyssner 

 ( 19231), who approved unconditionally only 15 analyses out of 235 which allegedly 

 proved the presence of mahc acid. 



No claim for completeness is made for table lO.I, and the following notes also 

 represent only a small part of the material on which a complete review of the subject 

 should be based. More material can be found, e. g., in Czapek's Biochemie der Pflanzen, 

 Volume III (1925), and in an article by Bennet-Clark (1933). 



Notes to Table 10. 1 



(1) Formic acid was called by Bergmann (1882) "a common constituent of all 

 leaves." Curtius and Franzen (1912*, 1914) found it in hornbeam leaves. These 



