54 BOTANICAL GAZETTE [JULY 
that a peroxide of the substance undergoing oxidation is the usual 
intermediate product. Thus, when rubidium burns in air it is 
converted quantitatively into rubidium peroxide: Rb+0.,= 
RvO,; and as BAEYER and VILLIGER’ have shown, when benzalde- 
hyde is exposed to oxygen, or to the air, it first absorbs oxygen to 
form benzoyl-hydrogen peroxide: 
C;:H,CHO+0.=C,H,CO—O—OH. 
benzaldehyde benzoyl-hydrogen peroxide 
If allowed to remain in contact with water, the benzoyl-hydrogen 
peroxide is hydrolyzed with the production of benzoic acid and 
hydrogen peroxide: 
CH sCO- —0-OH+HOH = CoH,COOH+ H.0.. 
hydrogen peroxi benzoic acid 
If a second molecule of benzaldehyde comes in contact with the 
benzoyl-hydrogen peroxide, however, the former is oxidized and 
two molecules of the acid are produced: 
CsH,CO—O—OH+C;H,;CHO= 2C;H;,COOH. 
benzoyl-hydrogen peroxide benzaldehyde ; benzoic acid 
Finally, if an oxidizable substance, such as indigo, be present, 
it is oxidized by the benzoyl-hydrogen peroxide with the produc- 
tion of isatin and benzoic acid, thus: 
CxsHoN 0+ CoH,CO—O—H= 2CiHNO.+ 2CsHl,COOH. 
oyl-hydrogen peroxide 
Hence Ame the intermediary action of the benzoyl-hydrogen 
peroxide benzaldehyde is oxidized to benzoic acid; or a second 
oxidizable substance, which is not acted upon by atmospheric 
oxygen, may also be oxidized by the peroxide. 
< More direct evidence that the oxidations within the organism 
follow this peroxidase procedure has been given by Bacu and 
CHODAT,* who were able to isolate a peroxide from the fresh juice 
of Lathraea squamaria at a time when it exhibited active oxidase 
action. After long standing, however, when the juice had lost its 
oxidase activity, it contained no peroxide. These investigators 
accordingly concluded that the oxidase itself is of a peroxide nature 
or contains a peroxide as one of its constituents. This conclusion 
3-Ber. Deutsch. Chem. Gesells. 33:1569-1585. 1900. 
4 Ber. Deutsch. Chem. Gesells. 35: 2466-2470. 1902. 
