2 2 British Fitno-i, 



i> 



pbcnomenon is summarized as follows by De Bary,^ 

 " Schonbein has carefully examined this phenomenon, 

 and finds that it is a substance capable of being 

 extracted from the fungus by alcohol, and probably 

 of a resinous character which turns blue in the air. 

 The blue colour appears in the alcoholic solution under 

 the same conditions as it does in a solution of guaiac- 

 resin, and since it has been proved that the colour is 

 produced in the latter by combination with ozonized 

 oxygen, Schonbein assumes a similar cause of the blue 

 colour in the fungus. The alcoholic extract from the 

 Boletus does not by itself become blue when exposed 

 to the air ; there must therefore be another substance 

 contained in the fungus, which ozonizes the oxygen of 

 the atmosphere, and then effects a combination with 

 the resin, giving off the oxygen to it in the state of 

 ozone. Phenomena of a similar kind, observed in 

 other cases, confirm this conjecture. Thus both the 

 tincture of guaiac and the alcoholic extract of Boletus 

 turn blue at once, if they are allowed to fall in drops 

 on the fresh tissue of some of the Agarici which 

 do not themselves turn blue, especially Agaricus 

 sanguineus. The watery juice of Agaricus san- 

 guineus squeezed out from the plant and filtered, 

 produces the blue colour at once in both tinctures. 

 From these facts it may be concluded that a number 

 of fleshy fungi contain a substance soluble in water, 

 which absorbs oxygen and gives it up to other bodies 

 in the state of ozone. The Boleti which turn blue 

 contain this substance, with another resinous sub- 



6 Yol. cit., p. 15. 



