REVIEW OF ANALYTICAL DATA 251 



results were criticized by Fincke (1913); but Franzen and Wagner (1918) and Franzen 

 (1920) confirmed the presence of HCOOH in distillates from chestnut and oak leaves. 



(2) Formaldehyde: see page 255. 



(3) Methanol: 0.02-0.05% found in Hedera leaves, Nicloux (1913); found in horn- 

 beam leaves, Curtius and Franzen (1914); in chestnut leaves, Franzen and Wagner 

 (1918); in oak leaves, Franzen (1920). 



(4) Oxalic acid, one of the most common of the leaf acids. See page 262. 



(5) Glyoxalic acid: found (but the test was probably unspecific) in the juice of 

 green grapes and other green berries and in leaves, Brunner and Chuard (1886). In 

 Chlorella, particularly after illumination, Kolesnikov (1940). 



(6) Glycolic acid: found in Amphelopsis hederacea, Gorup-Besanez (1872). See also 

 Ordonneau (1891), Shorey (1899), Stolle (1900), von Euler (1906), Fincke (1914). 



(7) Glycolaldehyde: 0.01 g. found per 2 kg. of potato leaves. Rouge (1921). See 

 Fincke (1914). 



(8) Acetic acid: found in hornbeam leaves, Curtius and Franzen (1912^, 1914); in 

 chestnut leaves, Franzen and Wagner (1918); in oak leaves, Franzen (1920). 



(9) Acetaldehyde: found in Agave mexicana, Rouge (1921); in more than 20 species 

 of leaves, Maze (1920); in hornbeam, chestnut and oak leaves ("most abundant leaf 

 aldehyde next to hexenaldehyde"), Curtius and Franzen (1912'', 1914), Franzen and 

 Wagner (1918), Franzen (1920); 0.01-0.001% in succulent leaves, Bennet-Clark (1933), 

 Gustafson (1934). According to Griebel (192412, 1925) and Klein and Pu-schle (1925, 

 1926), acetaldehyde is an intermediate product of plant respiration, and can be trapped, 

 e. g., by means of dimedon {cf. page 256) in respiring flowers and leaves. 



(10) Ethanol: found in 29 leaf species, Maz6 (1920). 



(11) Mesoxalic acid: found in Medicago sativa, von Euler and Bolin (1909). 



(12) Lactic acid: found in Agave siciliana, McGeorge (1912). According to Franzen 

 and Stern (1921), only four out of hundreds of assays for lactic acid in plants, pubhshed 

 before 1921, are rehable; one of them is in the leaves of Agave. Found in raspberry 

 leaves by Franzen and Stern (1921, 1922); 0.8% of dry weight of blackberry leaves, 

 Franzen and Keyssner (1921, 1923-); present in Lactuca, Rubus, Rheum, and Viciafaba, 

 Schneider (1939). 



(13) Lactaldehyde: present in poplar leaves, Maz^ (1920). 



(14) Propionaldehyde: found in chestnut leaves, Franzen and Wagner (1918). 



(15) Dihydroxjjmaleic acid: probably present in Chlorella, Kolesnikov (1940); in 

 Glaucium, Schmallfuss (1923). 



(16) Tartaric acid. According to Franzen and Helvert (1923^), among 82 pubhshed 

 assays only five are reliable and one probably correct; none of them refers to leaves. 

 No tartaric acid was found in blackberry leaves by Franzen and Schumacher (1921); 

 however, it is present in Vitis vinifera leaves, according to Klein and Werner (1925). 

 Over 5% Z- tartaric acid was found in leaves of Bauhinia reticulata by Rabat^ and 

 Gour^vitch (1938). 



(17) Malic acid: together with oxalic and citric acid, the most common plant acid, 

 particularly in succulents and fruits, but also in ordinary green leaves. See page 262. 



(18) Fumaric acid: in tobacco leaves. See Vickery and Pucher (1931). 



(19) Succinic acid. According to Franzen and Ostertag (1923), out of 33 pubhshed 

 assays only 10 are reliable and one probably correct; among them, 6 refer to leaves. 

 Later results: 0.009% of dry weight in blackberry leaves, Franzen and Keyssner (1923); 

 "small quantity" in raspberry leaves, Franzen and Stern (1922); up to 1% in some 

 leaves, but present in traces in all, Pucher and Vickery (1940); 0.5% in tobacco; 0.2% 

 in maize and Bryophyllum; 0.03% in buckwheat, Pucher and Vickery (1941). 



