130 
During the last two or three years Dony-Henault ( 143 ) and his 
co-workers have carried out a number of investigations on the sub- 
ject of the oxidases. According to this author the oxidizing action 
of laccase is not really due to a specific enzyme but to the presence of 
manganese salts, the activity of which is stimulated by hydroxyl ions. 
He is inclined to the opinion that too much stress has been laid on the 
inhibition of catalytic processes by heat, as indicative of the action of 
enzymes. On the other hand he is of the opinion that in the presence 
of colloids, manganese salts would be decomposed in aqueous solution 
by heating to 100° C., and thereby lose their oxidizing power. Arti- 
ficial laccase has been prepared by this author ( 144 ) by adding iron 
formate to blood serum and twice precipitating with alcohol. The 
substance thus obtained was found to show the reactions character- 
istic of natural laccase, but much less intensely. Still other artificial 
laccases were prepared by precipitating gum arabic with alcohol in 
the presence of manganous and other salts. A very active preparation 
was obtained by precipitating a solution containing 10 grams of 
gum arabic, 1 gram of manganese formate, and 0.4 gram of crystal- 
lized sodium carbonate in 50 c. c. of water, with alcohol. The 
precipitate was filtered off, redissolvecl in water, filtered, and repre- 
cipitated. This second precipitate when washed and dried consti- 
tuted the active, artificial laccase. The fact that artificial laccases 
can be obtained without resorting to the use of albuminous substances 
in these preparations, as was done by Trillat ( 436 ) , indicates that 
Bertrand’s idea that laccase contains an acid proteid radical is 
incorrect. Dony-Henault is of the opinion, therefore, that laccase 
as a distinct oxidizing enzyme does not exist. He explains the 
hardening and blackening of the juice of the lac-tree as due to the 
action of manganese in the presence of alkalis. 
This author has also criticised all previous work on the oxidases on 
the ground that whereas in the study of the digestive ferments we 
have employed for the investigation the true substratum upon which 
they normally act, thus for diastase we use starch and for invert ase, 
cane sugar, the action of the oxidases has been studied upon artificial 
or fictitious substrata, such as guaiacol, hydroquinone, etc. He 
therefore distinguishes between diastatic or enzvmic action and cat- 
alytic action, the former being specific whereas the latter is variable or 
general, and he concludes that for the reason that the known oxidizing 
ferments act upon a number of oxidizable substances, they can not be 
true enzymes. He is of the opinion, therefore, that the belief in the 
existence of oxidases proper does not rest upon a sufficiently rigorous 
experimental basis. On the other hand it would seem preposterous 
to assume the existence of several dozen or a hundred distinct lipo- 
