54 
notion that the change of color is brought about by an oxidizing fer- 
ment which they held to be identical with laccase. The cliromogen 
of the blue substance was later isolated by Bertrand and called 
boletol ( 60 ) . On the other hand it was known that certain fungi 
become red and then black (not blue) on exposure to the air. In 
such fungi Bertrand and Bourquelot ( 64 ) found tyrosin. Now, since 
this compound is not oxidized by laccase but is oxidized by the fresh 
extract of those fungi in which it occurs, they ascribed its oxidation to 
a second oxidizing ferment which they called “ tyrosinase. ” Bour- 
quelot found tyrosinase in many plants, including the potato and 
sugar beet. 
From these observations Bertrand was led to regard laccase as one 
of a group or class of oxidizing ferments to which he gave the general 
name of “oxydases.” Thus in an article on the relationships exist- 
ing between the constitution of certain organic compounds and their 
oxidizability under the influence of laccase he ( 52 ) says in footnote 2, 
on page 793: 
I propose to apply the generic term oxydases to soluble oxidizing ferments in order 
to distinguish them from the true diastases (ferments) which produce double decom- 
position with the fixation of water. 
To Bertrand, therefore, we owe the introduction into the science 
of the term oxydase. 
Boutroux ( 92 ) has objected to the use of the term oxydase as pro- 
posed by Bertrand for such oxygen carriers as laccase and that con- 
tained in bran, on the ground that the termination -ase has been em- 
ployed exclusively to indicate a hydrolytic ferment, and for the 
further reason that the formation of such a word as oxydase is con- 
trary to the general rule governing the nomenclature of enzymes, 
according to which the stem of the word thus employed designates 
the substances upon which the enzyme exerts its action; thus maltase 
signifies the ferment which hydrolyzes maltose. On the other hand it 
should be borne in mind that this nomenclature for the unorganized 
ferments has never been rigorously applied, as indicated by the use of 
the terms invertase and diastase. Furthermore, the term oxydase was 
well chosen, since these ferments all act upon oxygen or a peroxide, 
and such terms as laccase and tyrosinase, etc., serve to differentiate 
the oxydases from one another and likewise indicate the substances 
upon which the oxygen acts. 
As is the case with other soluble ferments, the oxidases have prob- 
ably never been obtained in a condition of purity. Indeed, we have 
no reliable criteria whereby to judge of their purity, and hence but 
little is known regarding their composition. From the fact that lac- 
case always contains manganese, and that a salt of this metal greatly 
increases the activity of the oxidase, Bertrand reached the conclusion 
that laccase consists of manganese in combination with a proteid 
radicle. The former functions in the capacity of a co-ferment 
