262 SCIENCE PROGRESS. 



firmed Schoenbein as to the existence of a special chromogen 

 in the tissue (13). 



In the light of the recent work on the oxidases the 

 authors were led to the view that one of the latter probably 

 is concerned in the alteration of the chromogens. Accord- 

 ing to Schcenbein there is evidently something concerned 

 besides the chromogen, and in his opinion the work effected 

 by the particular constituent in question is the transforma- 

 tion of oxygen into ozone. Whatever it may be it co- 

 operates with the oxygen of the air in causing the oxidation 

 of the chromogen. As this is apparently the part played 

 by laccase in the formation of the lacquer varnish, it seems 

 probable that Schcenbein's hypothetical oxygen transformer 

 is really an oxidising enzyme. 



Working on this hypothesis Bourquelot and Bertrand 

 carried out the following experiment. A definite weight 

 of Boletus cyanescens Bull, was extracted with boiling alcohol 

 of 95 per cent, concentration, the fungus being cut up as 

 far as possible out of contact with air. The extraction was 

 continued for a quarter of an hour, after which the liquid was 

 cooled and filtered. The alcoholic extract so prepared was 

 faintly yellow in colour, and it contained the substance 

 which normally turns blue on exposure. It retained its 

 colour for a considerable time, even when diluted with water 

 and allowed to stand in contact with air. 



To such an extract, diluted with its own volume of water, 

 the investigators added a small quantity of the extract of 

 Russula prepared as described above. In half a minute a 

 purple coloration appeared, which passed rapidly into blue. 

 The same effect followed on the addition of a little laccase 

 prepared from the latex of the lacquer tree. If the enzyme 

 was added slowly without agitation the tint was seen to be 

 assumed gradually, the upper layers of the liquid in contact 

 with the air being coloured first and the tint spreading 

 thence throughout the whole. 



Hence these investigators infer that the oxidase which 

 can effect these changes is identical with the laccase of 

 Rhus and other plants, and that in addition to acting on 

 aromatic bodies, such as hydroquinone and pyrogallol, it 



