122 
containing derivatives which are responsible for the guaiacum test 
and similar reactions. Buckmaster ( 104 > 105 ) also regards the oxidizing 
power of blood in the presence of hydrogen peroxide as due to a 
pseudo-peroxidase and in some way dependent on the part played by 
iron in the hemoglobin molecule, although the precise way in which 
the iron acts is still obscure. Studies on the oxygen-carrving power of 
blood toward solutions containing hydrogen peroxide, phenolphthalin, 
and alkali have also been made by Kastle and Amoss ( 241 ) and later 
by Kastle ( 240 ), who has recently recommended this reaction as a 
chemical test for blood. It has been shown that the amount of 
phenolphthalin oxidized both in the presence and absence of hydro- 
gen peroxide is proportional to the quantity of hemoglobin present, 
and that while the oxygen-carrying power of the blood is somewhat 
diminished, it is by no means entirely destroyed even after repeated 
boiling. The formed elements of the blood therefore contain oxi- 
dases, peroxidases, catalases, and a more stable oxygen-carrier, viz, 
hemoglobin, or, in certain of the lower animals, hemocyanin. To the 
catalases we owe the active decomposition of hydrogen peroxide into 
water and molecular oxygen, as shown by blood and pus. To the 
oxidases we owe the oxidation of guaiacum, phenolphthalin, and simi- 
lar substances, as shown by aqueous solutions of the leucocytes. To 
the peroxidases we owe those oxidations which take place only in the 
presence of hydrogen peroxide or a similar compound, as also shown by 
the leucocytes. These properties are all lost on boiling. On the other 
hand, certain oxidations by means of hydrogen peroxide are induced by 
hemoglobin and its iron-containing derivatives, and hence we find that 
the blood can still induce certain oxidations by hydrogen peroxide 
even after it has been boiled. The fact that these carriers become 
inactive with the splitting of! of the iron which they contain is a 
matter of great interest in view of the part played by iron and manga- 
nese in the activation of the oxidases and in view of the relation of 
iron to active nucleo-proteids. 
The fact that hemoglobin and its iron-containing derivatives oxidize 
various chromogenic substances in the presence of hydrogen peroxide 
has been turned to practical account in hematological and forensic 
investigations. This subject has recently been discussed at length 
by Kastle ( 24 °) in a communication entitled ‘‘Chemical Tests for 
Blood,” in which there is given a reasonably complete bibliography of 
the extensive literature of this subject. 
IRON, COPPER, AND MANGANESE IN THEIR RELATION TO THE OXIDIZING 
FERMENTS. ARTIFICIAL OXIDASES, PEROXIDASE ACCELERATORS, AND 
AUXILIARY OXYGEN CARRIERS. 
According to Spitzer ( 407 ) the oxidizing power of animal tissues is 
referable to certain nucleo-proteids which they contain, and the 
oxidizing power of these substances is in turn referable to combined 
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