109 
tissue or ferment to decompose hydrogen peroxide can be destroyed 
by certain degrees of heat and by certain poisons which have no action 
on the other ferments present in the preparations. Similar conclu- 
sions were also reached by Loew ( 278 ) in his work on catalase. (See 
also Bourquelot ( 83 ).) Hence we have come to regard the peroxidases 
and catalases as distinctly specific enzymes. Apparently, therefore, 
three distinctly different sets of substances are concerned in vital 
oxidations: First, the oxidases, by means of which the oxygen of the 
air is rendered sufficiently active to effect the oxidation of guaiacum 
and other oxidizable substances directly; second, the peroxidases 
which render active the oxygen of hydrogen peroxide and other 
peroxides (including the oxygenases) ; and third, the catalases, which 
decompose hydrogen peroxide into water and molecular oxygen, 
without, apparently, being able to activate the oxygen of the perox- 
ide toward oxidizable substances. 
Schoenbein ( 383 ) included the peroxidases and catalases among his 
oxygen-carriers and catalysts (Sauer stoff err eg er and Sauerstoffueber- 
trager ) without apparently assigning particular names to these par- 
ticular groups of carriers. Later, those substances which induce the 
oxidation of guaiacum and similar reagents through the agency of 
hydrogen peroxide and which lose this property on boiling, were 
called by Bourquelot ( 83 ) ‘“indirect oxidizing ferments” (ferments 
oxydants indirect), and in 1898 Linossier ( 273 ) gave them the name 
of peroxidases as signifying those substances whose function it is to 
decompose hydrogen peroxide and other analogous peroxides and 
thereby induce oxidations by means of these peroxides. The term 
“catalyse" was proposed by Loew ( 278 ) for those ferments which 
decompose hydrogen peroxide into water and molecular oxygen with- 
out apparently being able to activate the oxygen of the peroxide 
toward readily oxidizable substances. 
The peroxidases and catalases seem to be even more widely dis- 
tributed in various living tissues of the plant and animal than the 
oxidases. To such an extent is this the case that the properties of 
these substances might almost be turned to account as a general 
chemical test for vital activity. It can certainly be said of any liv- 
ing tissue or organ that it is dead when it fails to show the reactions 
of the peroxidases and catalases. Thus Brocq-Rosseu and Gain ( 10 °), 
in their observations on the duration of the peroxidases in grains, 
found that all seeds which retained their germinating power con- 
tained peroxidases, and in corn peroxidases were recognized by these 
observers (") in samples of the grain over two hundred years old. On 
the other hand, it was observed by these authors that the peroxidase 
activity outlasts the power to germinate by a hundred years. In 
other words, it would appear that peroxidase activity is one of the 
most characteristic and persistent properties of living material. 
