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CLASSIFICATION OF THE OXIDASES. 
Various attempts have been made from time to time by different 
observers to effect a classification of the oxidases. Xone of these are 
altogether satisfactory, but are probably as good as can be made in 
the present state of our knowledge of these substances. 
According to Grtiss ( 20 °) there are three classes of oxidases in the 
higher plants, namely a-oxidases, 3-oxidases, and /•'-oxidases. The 
u-oxidases (1) act directly upon guaiacum and tetramethyl-para- 
phenylene diamin with the fixation of oxygen; (2) they are soluble 
in glycerine and are partially precipitated from their solutions by 
acetate of lead, and are easily destroyed by alcohol; (3) they are 
found in the parenchymatous tissue of the potato and in most 
dicotyledenous plants. The ,3-oxidases (1) activate the oxygen 
of peroxides, and hence they only blue guaiacum or act upon 
tetramethyl-para-phenylene diamin in the presence of hydrogen per- 
oxide or a similar substance : (2) they are soluble in glycerine and are 
precipitated from their solutions by alcohol and ether without being 
destroyed; (3) they have been found in the resting, mature tubers 
of the potato. The T'-oxidases (1) also activate the oxygen of 
peroxides, and hence only blue guaiacum or act upon tetramethyl- 
para-plienylene diamin in the presence of hydrogen peroxide; (2) 
thev are not destroved even bv boiling alcohol, and in order to demon- 
strate their presence the tissue must be boiled in alcohol for a short 
time before adding the hydrogen peroxide and oxidase reagent; (3) 
they have been found in old wounds in plants such as the potato, in 
the diastase of the barley grain, in association with cytase, in the lep- 
tome of growing roots, in AstragaTlus glyeophylloides, etc. 
Gruss has also classified certain of the vegetable oxidases according 
to differences in conduct toward certain oxidase reagents. Thus he 
observed that certain oxidases can act upon tetramethyl-para- 
phenylene diamin, but not upon guaiacum, whereas other vegetable 
tissues are capable of oxidizing both. He therefore divided the 
oxidases into two groups: (1) the guaiacum-oxidases, and (2) the 
amino-oxidases. An example of the latter is furnished by the oxidase 
of yeast. In this connection Rey-Pailhade ( 342 ) was able to find only 
two kinds of oxidases in plant tissues, (1) those which oxidize guaia- 
cum and (2) those which only oxidize Rohmann-Spitzer’s reagent 
(a-naphthol and para-phenylene diamin). The first is identical 
with Bertrand’s lac-case; the second with the indophenol-forming 
oxidases which occur so generally in animal tissues. In this connec- 
tion Pohl( 329 ) found certain plant extracts to give the indophenol 
reaction, but to be incapable of oxidizing formaldehyde. 
