121 
corpuscles which exhibits the properties of an oxidase to a marked 
degree, as shown by its power to oxidize guaiacum, guaiacol, hydro- 
auinon, etc. 
In the light of these facts there can scarcely be any doubt that cer- 
tain of the leucocytes contain both oxidases (see also Portier ( 331 » 332 >)) 
and peroxidases. 
Dr. Norman Roberts, working in the Hygienic Laboratory on the 
peroxidase activity of the urine in health and disease, has examined 
the urines of 175 diseased persons and also the urines of a considerable 
number of normal individuals for peroxidases. As nearly as he has 
been able to discover, the peroxidase reaction of urine is not specific- 
ally characteristic of any of the diseases studied, except such as in- 
volve an active inflammation of the genito-urinary tract. It does 
seem to be constant, however, for active inflammations of this char- 
acter and is due to the leucocytes and possible in some instances to 
certain epithelial cells which these urines contain. He has also shown 
that in fresh blood smears and fresh sections of highly vascular tissues 
the majority of the leucocytes are stained blue on treatment with the 
peroxidase reagent (a solution containing cresol, para-phenylene di- 
amin, and hydrogen peroxide), whereas the red cells of the blood and 
the cells characteristic of the tissues examined remained unstained. 
(See also Winkler ( 453 ).) As is well known, pus also actively decom- 
poses hydrogen peroxide. 
In the light of these facts there can scarcely be any doubt that cer- 
tain of the leucocytes contain oxidases, peroxidases, and catalases. 
We have seen further that Senter ( 400 ) has prepared a very active 
catalase from defibrinated blood, free from hemoglobin and from any 
oxidase or peroxidase. While, therefore, the blood undoubtedly 
contains oxidases, peroxidases, and catalases, it has gradually come 
to be recognized that its oxygen-carrying power can not be due en- 
tirely to oxidases and peroxidases, for the reason that this oxygen- 
carrying power persists after boiling, and after treatment with acids 
and alkalis. Indeed it seems to persist as long as the blood pigments 
are not deprived of their iron. Thus according to Moitessier ( 305 ) the 
so-called peroxidase reaction of the blood, upon which is based most 
of the chemical tests for blood, is not really due to a peroxidase but 
to hemoglobin and hematin. According to this author the non-fer- 
ruginous blood pigments, such as hematoporphyrin, do not exhibit 
such reactions. Czyhlarz and von Furth ( 131 ) have also arrived at the 
conclusion that the so-called peroxidase reaction of the blood is due 
to hematin and not to a peroxidase. Lesser ( 267 ) also obtained the 
guaiacum reaction with blood which had been boiled. He also is of 
the opinion that the reaction is due to the blood pigment and that 
the iron-free derivatives of hemoglobin do not give it. Whitney 
( 450 ) also concludes that it is the iron of the hemoglobin and its iron- 
