46 
contains, after the manner of a lead salt, as indicated by r the fact 
that a solution containing the peroxide and red blood corpuscles 
rapidly blues a tincture of guaiacum. In the light of these facts, 
therefore, one can readily understand, he says, why the red blood 
corpuscles have the power of rapidly decomposing hydrogen peroxide, 
nor should one be inclined to look upon this as a useless property, 
since the blood corpuscles also have the power of ozonizing a part of 
the oxygen of the peroxide after the manner of platinum or a lead 
salt. According to Schoenbein, therefore, the red blood corpuscles, 
by virtue of their activating and catalyzing properties, play an 
important role in all processes of oxidation occurring in the organism 
of the higher animals, inasmuch as it is scarcely conceivable that 
their oxidizing power should be confined entirely to guaiacum resin 
or pyrogallic acid. 
So far as the historical development of the subject is concerned, the 
work on the oxidases is approximately divisible into three periods. 
The first period begins with the earlier observations by Planche, 
Taddei, and Schoenbein, on the bluing of guaiacum. The second period 
has to deal with the work of Moritz Traube. The third period begins 
with the work of Yoshida and Bertrand on laccase, and includes all 
recent investigations on the subject. Obviously, as is the case with 
all things historically considered, the work of each of these periods 
overlaps somewhat the work of the other periods. 
To review briefly the salient facts brought to light during the first 
period, we note that Wollaston was the first to call specific attention 
to the bluing of guaiacum and to the part played by air and light in 
effecting this change. William Braude also ascribed this change of 
color to oxygen, and succeeded in showing that pure oxygen gas effects 
the change somewhat more rapidly than atmospheric air. Then 
followed the earlier observations of Planche, that guaiacum is rapidly 
blued by the vapors of nitric acid and also by the fresh root of the 
horse-radish. This last-mentioned observation, made in 1809, marks 
the first recognition of a change brought about by an oxidizing 
ferment, although the ferment-like nature of the substance causing 
the change was not definitely recognized until many years afterwards. 
Other French observers noted a bluing of guaiacum b}" gums, such as 
gum arabic, and also by saliva. Taddei showed that under the 
influence of air and moisture the gluten of wheat flour blues guaiacum, 
and Planche showed that this reaction is characteristic of the roots 
of a large number of plants, and also of fresh milk, and, further, that 
the power to blue guaiacum on the part of these substances was lost 
on boiling. Thus, without fully appreciating its significance, this 
observer discovered one of the most characteristic properties of the 
oxidases as a class, viz, the loss of oxidizing power on boiling. 
Planche however failed to recognize the part played by atmospheric * i 
