13 
dase, and, for lack of a better term, Kastle and Amoss (80) have used 
the expression peroxidase activity” of the blood as descriptive of 
the oxidation of phenolphthalin b}^ hydrogen peroxide under the in- 
fluence of blood as an oxygen carrier. They were careful to point 
out, however, that in its capacity as an oxygen carrier, blood ex- 
hibits certain important differences from the true peroxidases, among 
which may be mentioned the fact that it does not lose its activity as 
an oxygen carrier on boiling, and that it reacts in alkaline solutions 
of sufhcient concentration to destroy many, if not all, of the true 
peroxidases, and further, that the activity was found to be propor- 
tional to the hemoglobin content. 
Lumiere and Chevrotier (109) claim to have shown that an aqueous 
extract of frozen and washed blood'corpuscles possesses the properties 
of an oxidase to a remarkable degree. 
According to Carlson (33) the action of blood on hydrogen peroxide 
and guaiacum is due to some organic constituent of the blood. 
It has gradually come to be recognized, however, that the oxygen- 
carrying power of blood can not be due entirely to the presence of 
oxidases and peroxidases, for the reason that the oxygen-carrying 
power persists after boiling and treatment with acids and alkalis. 
Indeed, it seems to persist as long as the blood pigments are not de- 
prived of their iron. Thus, according to Moitessier (117) the so- 
called peroxidase reaction of the blood is not really due to a peroxi- 
dase but to hemoglobin and hematin, nor do the nonferruginous blood 
pigments, such as hematoporphyrin, exliibit such reactions. Czyhlarz 
and von Ftirth (43) also arrived at the conclusion that the oxidizing 
reaction is due to hematin and not to a peroxidase. Lesser (101) has 
also observed that blood' gives the guaiacum reaction after it has 
been boiled, and that the reaction is'due to the blood pigment, and 
further that the iron-free derivatives of hemoglobin do not give it. 
Whitney (203) also concludes that it is the iron of the hemoglobin 
and its iron-containing derivatives wliich are responsible for the 
guaiacum reaction. As alread}^ pointed out, the importance of the 
iron of the blood pigments in such reactions was recognized by 
Schoenbein and his colleague. Hiss, according to whom the oxidizing 
power of the blood is proportional to its iron content. 
Buckmaster (29) also concludes that tliis test depends on some 
part played by the iron in the hemoglobin moiecifle. According to 
this author, however, the precise way in wliich the iron acts is still 
obscure. It can not be due merely to a ferric salt ; the iron must act 
while the change is taking place. He suggests that the moment the 
iron is split off from the hemoglobin molecule it acts toward guaiacum, 
not as a carrier of oxygen, but as a direct oxidizing agent, causing the 
oxidation of the guaiacum to guaiacum blue in a manner similar to 
the action of iodine. 
