404 THE OXYDASES. 



The so-called rusting or tarnishing of many of the agarics, Le. 

 the rapid discoloration of freshly broken or cut surfaces in the 

 body of the fungus, is well known. The bluing of two of these, 

 which he styled Boletus luridus and Agaricus sanguineus (?), was 

 explained by CH. SCHONBEIN (I.) in 1856, by stating that these 

 fungi contain a resinous substance soluble in alcohol (the above-men- 

 tioned reaction with guaiacum tincture will be remembered !), and 

 becoming converted into a blue oxy-compound when brought into 

 contact with ozone. The formation of this latter from the oxygen 

 of the air is accomplished by the activity of another substance, 

 also present in the fungi, and destructible by heat. This active 

 substance was subsequently (in 1895) proved by E. BOURQUELOT 

 and G. BERTRAND (I.) to be an oxydase, and was detected by them 

 in 59 out of 107 species examined : e.g. in 18 species of the genera 

 Russula and Lactarius, 10 species of the genus Boletus, 2 species 

 of the genus Amanita, &c. According to the researches of BOUR- 

 QUELOT and BERTRAND (II.), the enzyme giving rise to the bluing 

 of Boletus cyanescens is similar to laccase ; but another oxydase, 

 causing the freshly fractured surfaces of Russula nigricans to first 

 turn red and finally become black, is certainly different. 



G. TOLOMEI (VI.) discovered in ripe olives an oxydase which 

 he called olease. In many parts of Italy it is customary to allow 

 the olives, before putting them through the press, to undergo a 

 spontaneous decomposition, which is chiefly effected by this olease, 

 but has not yet been sufficiently investigated. This enzyme also 

 passes into the oil prepared at temperatures below 70 C., and pre- 

 sumably continues to convey oxygen gradually thereto as well, 

 oleic acid, acetic acid, sebacic acid, &c., being formed. 



Another phenomenon not yet accurately known (but possibly 

 also attributable to enzymatic activity) will now be considered, 

 since otherwise no convenient opportunity would offer, and that is 



216. The Bittering of Wine. 



This malady makes its appearance in many districts, such as 

 the French Jura (Burgundy wine), the Ahr valley (Rheinland), 

 Vb'slau near Vienna, and Sicily (Vino del Faro di Messina), with 

 comparative frequency, and almost exclusively affects red wines. 

 The commencement of the disease is evidenced by a reduction in 

 the acid content, the wine becoming apparently sweeter again 

 (French cellar-masters say "le vin doucine"). By degrees the 

 liquid turns paler, and is finally decolorised completely, the colour- 

 ing matter being deposited as an insoluble sediment or covering the 

 walls of the bottle as with a skin. Concurrently, the wine de- 

 velops a strange odour and a bitter after-taste, which finally becomes 

 so strong as to render the liquid undrinkable. This malady first 

 makes itself apparent in the second or third year of storage, and 

 oftentimes not before the wine is bottled for maturing. 



