56 
oxidize tyrosin, then guaiacol, and finally, after eight weeks, its power 
to oxidize guaiaeum. I have found aqueous extracts of Lepiota 
americana to oxidize guaiaeum at the end of eighteen weeks. Bertrand 
found tyrosinase to be very unstable. On the other hand, according 
to Bourquelot ( 75 ), aqueous solutions of tyrosinase to which chloroform 
had been added were found to be active at the end of two or three 
months. 
In glvcerin the oxidizing ferments are much more stable. ' Thus 
Gessard ( 181 ) has found that a solution of tyrosinase in glycerin, 
obtained from mushrooms by Bourquelot ’s method, is stable, and in 
his work he employed such an extract which had retained its activity 
for ten months. Bourquelot ( 81 ) found that glycerin extracts of 
Lactarius velutinus retained their oxidizing properties for a year or 
longer. In the course of my own work on this subject I have found 
that glycerin extracts of Lactarius piperatus and Lactarius volumen 
prepared in the summer of 1905, both of which, in the fresh state, 
were found to be quite active toward guaiaeum and tyrosin, were 
still active toward these substances in the summer of 1909. 
As a general thing, the oxidizing power of an oxidase is not con- 
fined to one particular oxidizable substance. Thus laccase has been 
found to oxidize not only laccol, the oxidizable principle of the juice 
of the lac tree, but also to oxidize guaiaeum, guaiacol, liydroquinone, 
phenolphthalin, and a large number of phenols and aromatic amino 
compounds. (See pp. 59-61.) So also tyrosinase oxidizes not only 
tyrosin but also a large number of related compounds. (Seepp. 81-84.) 
In the same way an oxidase which will oxidize benzaldehyde to ben- 
zoic acid will also oxidize salicylic aldehyde, benzyl alcohol, and 
related substances. On the other hand laccase will not oxidize tyro- 
sin, nor will tyrosinase oxidize guaiaeum or phenolphthalin. So in 
the same way many animal tissues which have been found to oxidize 
salicylic aldehyde are without effect on guaiaeum, liydroquinone, and 
tyrosin. TThile thus not absolutely confined in their action to any one 
particular oxidizable substance, the oxidases exhibit a certain degree 
of specificity in the sense that they are more or less limited in their 
action to certain groups of substances which are more or less closely 
related chemically . 0 
a From his studies on the spontaneous oxidation of the sugars, Mathews ( 2S9 ) concludes 
that two distinct groups of substances have been confused under the name of oxidases ; 
one group, the oxidases proper, activates oxygen more or less generally toward all 
oxidizable substances, while the other group of ferments, which are more specific in 
their action, activates certain oxidation processes, such as the oxidation of sugars, 
by causing a dissociation of the sugar molecule. For the latter he proposes the name 
metabolase, since they hasten metabolism. According to this author the failure on 
the part of the organism to burn glucose under certain conditions is probably not due 
to the absence of oxidases, but to the loss of its power to dissociate glucose into easily 
oxidizable substances. 
