THE CHEMICAL PROCESSES IN PLANT RESPIRATION I03 



ena were also observed for the autoxidation of aldehydes and 

 other substances. 



Thus it is clear that autoxidation does not lead directly to 

 the formation of oxides as seemed to be the case from the classic 

 experiments of Lavoisier. The processes of autoxidation are 

 rather to be regarded as instructive coupled reactions. After 

 their investigation the physiological significance of chemical 

 induction was first correctly understood. 



Schonbein^ was the first to conceive of the processes of autoxi- 

 dation as complicated reactions. He made the correct assump- 

 tion that the first phase of all autoxidative processes consists in 

 the change of inactive, molecular oxygen into an active form. 

 But Schonbein incorrectly pictured the activation of oxygen. 

 For this process he supposed that two bodies were formed — 

 negative ozone and positive antozone. At present this theory 

 is considered too weak to hold. 



Hoppe-Seyler- expressed his opinion to the elTect that the 

 activation of oxygen is nothing but a dissociation process. 

 Van't Hoff^ further developed this theory. According to him 

 the molecule of oxygen dissociates into two charged ions, 0+ 

 and 0~. If an oxidisable substance reacts with one ion, e.g. 

 with O"*", an oxidation of other substances can easily follow 

 through the action of the oppositely charged ion, 0~. In this 

 way van't Hoff believed he could explain the simultaneous 

 autoxidation of triethyl phosphine and indigo white as well as 

 other analogous processes.. 



This theory too met with only little approval. Thus 

 Bodlander^ points out that two oppositely charged atoms of 

 oxygen could hardly be separated by measurable distances. If 

 the latter is true a selective oxidation of different substances by 

 0+ and 0~ seems to be quite inconceivable. Engler and Weiss- 

 berg^ showed that the autoxidation of triethyl phosphine and 



' Schonbein, C. F. Verhandl. d. Xaturf. Ges. Basel. 3 : 516. 1863; Jour. f. prakt. Chem. 

 105:198. 1868; Zeitsch. f. Biol. 4: 367. 1868. 



-Hoppe-Seyler. Z. f. physiol. Chem. 2 : 22. 1878; Ber. d. chem. Ges. 12 : iSSi- 1879. 



3 van't Hoff. Z. f. physikal. Chem. 16: 411. 1895; Verhandl. d. Xaturf. Ges. Frankfurt. 

 2: 107. 1897; Ewan. Z. f. physikal. Chem. 16: 321. 189s; Jorissen. Ber. d. chem. 

 Ges. 30: I9SI. 1897- 



' Bedlander. Samml. chem. und chem.-techn. Vortrage von Arens 3 : 450. 1899. 



' Engler, A. und Weissberg. Ber. d. chem. Ges. 31 : 3055. 189S. 



