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BRADLEY and SANsuM *), were carried out with a blood solution and 
not with isolated haemoglobin. In a second series of experiments 
with erystallised haemoglobin these authors found that guinea pigs 
sensitized with dog’s haemoglobin reacted sfrongly (no acute death) 
on dog’s bloodsolution, in a lesser degree with such solutions from 
pig, and turtle and not at all with those from fowl, calf, horse, goat, 
rabbit, rat, guinea pig, sheep and man. This result does not allow 
of a definite conclusion yet. 
As the species differences of haemoglobin certainly are due to its 
protein components, the experiments on globin ought to be mentioned 
here. Browning and Witson *) found a strongly homologous reaction 
with an immune serum against guinea pig globin, weak complement 
fixation with rabbit-globin, and none with ox-globin. In a recent 
publication *) these same anthors find that an immune serum against 
ox-globin reacts also on globin of goats, guinea pigs and ducks but 
not on rabbit-globin. On this point they state, “Thus while evidence 
of species-speciticity exists in certain cases, there is also a wide 
though not universal, community of antigenic properties shared by 
the globin of widely separated animal-species’’. 
It ought still to be mentioned that some time ago ScamipT and 
Bennett *) on the ground of some previous (Forp and Harsrv) and 
of their own negative findings, deny the ability of haemoglobin to 
produce antibodies and they ascribe the positive results to impurities 
in the injected materials. 
BROWNING and Wirson, who themselves obtained a distinctly active 
serum against haemoglobin, believe that they can explain the 
negative results in this way, that haemoglobin possesses only a 
weak antigenic property. I am inclined to agree with this view ‘), 
as in my experiments with 5 animals with intensive immuni- 
sation (2 gr. of haemoglobin and more) only one gave a good 
active serum, 2 others very weak sera, whereas the sera of the 
remaining two were not active at all. I have no cause to doubt 
that the reactions obtained are really attributable to the haemoglobin, 
seeing that the active sera gave only very weak haemolysis with 
1) Journ. Biol. Chem. 18. 497. (1914). 
®) Journ. of Path. a. Bact. 14. 174. (1909). Cf. Gay a. Roperrson J. Exper. 
Med. 17. 535. (1913). 
8) Journ. of Immunol. 5. 417 (1920). 
4) Journ. infect. Dis. 25. 207, (1919). 
5) Perhaps alteration occur during the process of isolation, which diminish the 
antigenic properties. 
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