In the above diagram the solid black lines indicate the presence 
of the particular ferment to which it appertains, whereas the dotted 
lines indicate the absence of the ferment; the first diagram explains 
the four that follow. 
It is evident from these results that the production of uric acid 
from xanthin or hypoxanthin takes place directly as the result of the 
combined action of the xanthin-oxidase and molecular oxygen, whereas 
it can only be formed from guanin and adenin by previous desamidiza- 
tion through the action of guanase and adenase, respectively, which 
belong to the group of hydrolytic ferments. 
Reference has been made repeatedly to the wide distribution in 
nature, especially in the plant kingdom, of oxidases of the type of 
laccase. Whether these represent merely special occurrences of 
laccase or whether they are really distinctly different oxidases can 
not be determined in the present state of our knowledge. So far as 
one can judge from the experimental evidence now at hand it would 
seem probable, however, that all of these guaiacum-bluing vegetable 
ferments are praticallv indentical with laccase, and it is doubtful if 
there is much to be gained by the introduction of these new names, 
which after all only serve to tell something with regard to a special 
occurrence of the ferment without throwing any light on differences 
in properties, if such exist. On the other hand, Sarthou ( 357j 359 ) is 
inclined to the opinion that the oxidases are distinct substances 
which can not replace one another in the changes which they bring 
about. 
Irrespective of these differences of opinion, however, the following 
additional facts pertaining to their occurrence are of interest. 
Aso found oxidases in tea ( 15 ) and in kaki fruit ( 14 ) ; Loew ( 277 ) 
found them in tobacco, and Carles ( no ) in valerian; they have been 
found in the grapevine by Cornu ( 123 ), in plants of the genus Spirsea 
by Beijerinck ( 41 ), and in the vanilla bean by Lecomte ( 257 ). Accord- 
ing to Breaudat ( 95 ) indigo-producing plants contain two ferments, 
one a hydrolytic enzyme and the other an oxidase; the latter in the 
presence of alkali transforms indigo-white into indigo-blue. On the 
other hand Bergtheil ( 46 ) was unable to find an oxidase in the indigo 
plant. Bourquelot ( 86 ) has proved the presence of oxidases in cer- 
tain medicinal preparations and in certain gums such as gum arabic, 
gum senega!, etc. Lepinois ( 264 ) found an oxidase in aconite and 
belladonna, and Yadam ( 43Si 439 ) found an oxidase in hellebore. Sim- 
ilarly oxidases have been found in oleaginous grains by Maze ( 29 °) 
and in digitalis by Brissemoret and Joanne ( 98 ). 
As is evident from what has already been set forth in this mono- 
graph, the oxidases occur abundantly in the higher fungi. In addi- 
tion to this they have been found in different yeasts, such as Saccharo- 
myces ellipsoideus, S. cerevisise, and S. apicultus. According to . j 
