63 
ceivable, therefore, that such oxidases as laccase are not really absent 
from animal tissues, but that their presence is merely obscured by 
the presence of powerful reducing substances, whose affinity for their 
oxygen is so great as to prevent the oxidation of the oxidase reagent. 
Laccase is very soluble in water and aqueous solutions of the 
ferment are very readily obtained from such plants as the potato 
C Solarium tuberosum ) (tuber), from the fruit of the egg plant ( Solanum 
melongena), from the silk of the green corn ( Zea mays), and from 
many varieties of fungi. In my own experience Lactarius piperatus 
and Lepiota americana afford excellent material from which to obtain 
the ferment. The former yields nearly colorless water-clear extracts 
of considerable oxidizing power, while the latter fungus affords 
extracts of remarkable oxidizing power. In this connection glycerin 
extracts of Lactarius piperatus and Lactarius volumen, which had been 
kept in the laboratory in glass stoppered bottles for a period of four 
years, still showed the laccase and tyrosinase reactions strongly. (See 
p. 56.) It not infrequently happens that laccase occurs in association 
with tyrosinase in the same plant or even animal tissues. See Gessard 
( 185, 186 ), and Bertrand ( 54 ). In the separation of the two oxidases 
advantage is taken of the greater stability of laccase toward heat and 
alcohol. Thus from Russula delica Bertrand separated the two 
ferments by precipitating the aqueous extract obtained by macerating 
the fungus with its own weight of chloroform water, with one and one- 
half times its volume of 95 per cent alcohol. The filtrate thus 
obtained after concentration at 50° 0., still showed all of the reactions 
of laccase. It failed, however, to oxidize tyrosin. On the other hand, 
an aqueous extract of the alcoholic precipitate oxidized tyrosin, but 
failed to oxidize hydroquinone or pyrogallol to any appreciable 
extent. 
Similarly it was found possible to destroy the tyrosinase and leave 
the laccase in the aqueous extract by heating to 70° C. ( See Bach 23 ). 
In the preparation of laccase no special precautions are necessary 
other than those which hold for the preparation of ferments in general. 
If tyrosinase is present along with the laccase, the extract is either 
heated to 70° C. for a short time to destroy the tyrosinase, or the 
latter is precipitated by the cautious addition of alcohol. The tyro- 
sinase-free extract may then be concentrated by evaporation at low 
temperatures and the laccase finally precipitated by the addition of 
alcohol. Inasmuch as we have no criterion for judging of the abso- 
lute purity of a ferment, it is very doubtful whether much is gained 
by the attempt to isolate laccase and the other oxidases in pure con- 
dition, and it has been my own experience that we frequently lose in 
activity what we gain in the so-called purity of the enzyme by all 
attempts at its purification. The stability of laccase apparently 
depends upon the nature of the substances with which it finds itself 
in association or upon conditions which at present are altogether 
