158 DIFFERENTIATION AND SPECIFICITY OF STARCHES. 



1904, XXXVII, 2836), Berthelot and Gaudechon (Compt. rend., 1890, ex, 1690), Usher 

 and Priestly {loc. cit.), and Fenton (Jour. Chem. Soc, 1907, xci, 687). In the investiga- 

 tion of Bach, Berthelot and Gaudechon, Usher and Priestly, and Fenton formaldehyde 

 was found, and in several forniic acid was noted. Various other substances have been 

 used by chemists in the synthesis of formaldehyde, and other instances might be given 

 which have bearing upon aldehyde formation in plants. 



If sugar can be reduced to aldehyde in vitro we are justified in assimiing that the reverse 

 may be brought about under proper conditions. This finds confirmation in the investi- 

 gations of Konig, Spieckmann and Olig (Jour. Chem. Soc, 1903, lxxxiv, 386), who found 

 that bacteria (belonging to the type of Bacillus coli communis) in a solution of glucose 

 actually form acetic aldehyde and other compounds; and in those by Renard (Ann. d. 

 chim. e. phys., xvii, 321), who records that glucose when subjected to electrolysis in dilute 

 sulphuric acid yields among its products trioxymethylene, which in turn is changed into 

 formaldehyde, and that a reversal can be brought about so that formaldehyde is trans- 

 formed into sugar. 



Other successful experiments in the synthesis of sugar in vitro have been reported by 

 a number of investigators, as for instance, Loew (Jour. f. prakt. Chemie, 1886, xxxiii, 

 321; Ber. d. d. chem. Gesellsch., 1889, xxii, 475), Fischer (Untersuchungen u. Kohlenhy- 

 drate ii. Fermente, Berlin, 1909 a collection of papers that appeared in the Ber. d. d. 

 chem. Gesellsch., from 1884 to 1908), Lob (Zeit. f. Electrochemie, 1907, xii, 282, Biochem. 

 Zeit., 1907, XII, 78), Euler (Ber. d. d. chem. Gesellsch, 1906, xxxix, 39,45), Slosse (Bull. d. 

 I'Acad. roy. d. Belg., 1906, xxxv, 547), and Berthelot (Compt. rend., 1903, cxxvi, 610). In 

 some of these investigations intermediate bodies, such as a-acrose, a-acrosazone, f-fructose, 

 i-mannitol, i-mannose, i-mannonic acid, rf-mannonic acid, Z-gluconic acid, and d-gluconic 

 acid are recorded in the synthesis of glucose. The evidence, then, is conclusive that not 

 only may saccharine substances be formed from formaldehyde, but also sugar that cor- 

 responds with decomposition products of starch and glycogen. Glucose, as already stated, 

 has been converted into isomaltose. Moreover, having glucose as an initial substance, one 

 may obtain from it by appropriate methods in litro levulose, mannose, and other saccha- 

 rine substances. 



Of incidental interest is the fact discovered by Mayer (Zeit. f. physiolog. Chemie, 

 1903, xxxviii, 135) that glycollic aldehyde is eliminated by rabbits in the form of glucose. 

 The fact that aldehydases which oxidize aldehydes have been found in plants and also 

 in the li^'er and other organs of animals is not without significance. Gautier suggested 

 years ago that certain glucosides, such as arbutin and salicin, may be derived from formal- 

 dehyde by the addition of hydrogen by molecular condensation and dehydration. 



It has also been shown that plant substances may be broken down with the formation 

 of aldehyde, as for instance, salicin into helecin and this into salicylic aldehyde or glucose, 

 and amygdalin into benzoic aldehyde, glucose, and hydrocyanic acid. Acetic aldehyde 

 is produced in acetification, and in wines, etc.; and it is formed in the animal body as a 

 decomposition product. There are quite a number of both plant and animal substances 

 which by oxidation yield forms of aldehyde. In fact, instances of this character which 

 have for their indication a suggestion that aldehydes are among the plant metabolites 

 utilized in carbohydrate and other forms of metabolism might be considerably multiplied. 

 In the animal organism starch is not merely reduced to the glucose stage, but ultimately 

 to carbon dioxide and water. In other words, when diastatic enzymes cease their decom- 

 posing actions other enzymes which cause further hydrolysis, or simple molecular splitting, 

 oxidation, etc., come into play, by the agency of which a considerable number of products 

 are formed, among which are included alcohol and its aldehyde. 



Whether or not aldehyde is formed in plants is a matter yet under discussion. Evidence 

 in favor of the presence of this substance in plants has been offered m the investigations 



