PHYSIOLOGICAL ACTION OF NITROBENZENE VAPOR ON ANIMALS 425 
Filehne claims that nitrobenzene is not converted into hydrocyanic 
acid in the body, since, in the first place, the blood of animals poisoned 
by hydrocyanic acid is red while that of animals poisoned by nitrobenzene 
is dark brown; then, too, the action of hydrocyanic acid on muscle tissue 
is different from that of nitrobenzene, as Filehne was able to prove by 
experiments on frogs; furthermore, Filehne was unable to detect the 
slightest trace of hydrocyanic acid in the blood or other tissues of animals 
poisoned by nitrobenzene, even by tests so delicate as to detect the drug 
in dilutions of 0.0062 per cent. 
Nor will Filenhne concede that nitrobenzene is converted into anilin 
in the body. He was unable to find any trace of it, as were also Bergmann 
and Guttmann. He shows that Letheby’s method was at fault; that, 
according to Hoffmann and Muspratt, nitrobenzene when heated with 
alcoholic potash is converted into azobenzol, oxalic acid, and anilin. 
(Letheby apparently used the phenylisocyanide test, whereas Filehne 
applied the hypochlorite test.) 
Regarding the action of nitrobenzene on the blood, Filehne found 
that in frogs and mammals the blood was dark brown after poisoning 
by nitrobenzene, except in the case of rabbits, which, he thinks, die before 
the drug can act on the blood. He could find no morphological changes 
in the blood-cells, but by spectroscopic analysis he found an absorption 
band occupying a position between C and D near the position occupied 
by the absorption band of acid hematin. He called this band the nitro- 
benzol band. It is possible that he was not familiar with the methemoglobin 
band, since the formation.of methemoglobin was demonstrated only 
a few years prior to his experiments. Filehne was unable to produce 
the dark brown color in arterial blood by shaking it directly with nitro- 
benzene; he makes no statement regarding venous blood. By blood-gas 
analysis he demonstrated that the blood of animals poisoned by nitro- 
benzene had lost its ability to take up oxygen. He found the oxygen 
content of such blood to be less than 1 per cent, as against the normal 
17 per cent, while the carbon dioxide content had increased in both absolute 
and reiative amount. 
Filehne states that the toxicologists have placed the convulsion-producing 
poisons in two categories: (1) those that produce convulsions in both frogs 
and warm-blooded animals (specific convulsion-producing poisons) ; and (2) 
those that do not produce convulsions in frogs but do produce convulsions 
