NUTRITION 61 



ment upon the living plant, though based upon the relations 

 of the members of the sugar group to one another, a series 

 of equations suggesting the possible (some say probable) 

 stages of the photosynthetic process has been proposed by 

 organic chemists. * The following, proposed by von Baeyer, 

 has much in its favor : 



CO, + H 2 O = HCOOH + O = HCOH + O 2 



( Formic Acid ) ( Formic Aldehyde ) 



6n (HCOH) == n (C 6 H,O 6 ) == n(C 6 H 10 O 5 + H 2 O) 



(Sugar) (Starch) 



To this series of reactions there are evident objections : e. g. 

 formic acid and formic aldehyde are extremely poisonous, 

 they cannot be formed free in the cell unless their conversion 

 into harmless substances is Jnstantaneous. The union of 

 any of the alkaline elements with formic acid would imply 

 the decomposition of the salts in which these elements enter 

 the cell, namely, the phosphates, nitrates, sulphates, and 

 chlorides. The decomposition of these salts, assuming that 

 it could be immediately accomplished by formic acid or other- 

 wise, would set free in the cell acids which, though less pois- 

 onous than formic acid, would still be injurious. To neu- 

 tralize these another series of reactions would be necessary. 

 Pursuing this theoretical discussion further along this line is 

 unnecessary, for after all, assuming that the formic acid is 

 neutralized by sodium, potassium, or any other element in- 

 variably present in combination in the cell, and that the re- 

 duction of this to an aldehyde takes place, the alkaline element 

 must be eliminated to permit the condensation (polymeriza- 

 tion ) of formic aldehyde to sugar, and the element must be 

 united again with some inorganic acid to form a harmless 

 salt. There must, therefore, be at least one other series of 

 reactions taking place simultaneously with the others. 



Loew and Bokornyf have conducted experiments on Spiro- 

 gyra, using as sole source of carbon a 0.1% solution of 



* Baeyer, A. von. Uber die Wasserentziehung und ihre Bedeutung fur 

 das Pflanzenleben und die Gahrung. Berichte d. Deutch. Chemischen 

 Gesellsch., Bd. III., 1870. Fischer, E. Synthesen in der Zuckergruppe I. 

 ibid, Bd. XXIII., 1890. II. ibid., Bd. XXVII., 1894. 



t Loew, O. Ernahrung von Pflanzenzellen mit Formaldehyd. Botan. 

 Centralblatt, Bd. XLIV., p. 315-f . 1890. Bokorny, Th. tJber Starke- 



