PuHyYSsIoLoGicAL ACTION OF NITROBENZENE VAPOR ON ANIMALS 463 
benzene breath. In chronic cases the symptoms which persist are: 
asthenia, ataxia, and (described in man) anemia, malnutrition, and 
Korsakoff’s psychosis. 
INTERPRETATION OF THE SYMPTOMS NAMED 
While there is scarcely a single one of the symptoms described above 
that may not be referred to disorders of the central nervous system, 
still there is no doubt that nitrobenzene exerts a more or less serious 
local action on other tissues. The cyanosis observed in most cases of 
acute poisoning is undoubtedly due to a direct action of nitrobenzene 
on the blood; the blood has a dark brown color, and the presence of 
methemoglobin is demonstrable, at least in some cases, by spectroscopic 
analysis. Just how the changes in the blood are brought about is not defi- 
nitely understood. Roth (1913) thinks that the nitrobenzene is converted 
into paraminophenol and that the latter drug acts on the red blood-cells, 
forming intracellular methemoglobin; he found no methemoglobin in the 
serum of certrifugalized blood. Tiirk (cited by Adams, 1912) says that 
not only is there a forming of methemoglobin, but there is also a 
destruction of the erythrocytes, due, he thinks, either to intravascular 
hemolysis or to a hyperfunctioning of the blood-destroying organs. That 
methemoglobin is formed, in certain cases, was demonstrated by the 
writer’s experiments; the writer was unable, however, to demonstrate the 
destruction of erythrocytes, altho some morphological alterations of these 
cells were apparent. Also, Filehne (1878) has shown that nitrobenzene 
has a direct action on the muscle substance, causing the muscle to contract 
in rigor mortis; even the heart muscle was affected, according to him. 
Certain it is that nitrobenzene has an irritating action on the tongue 
and the mucosae; and, since it passes unchanged readily from the blood 
to other tissues, it is not impossible that it may have an irritating action 
on the deeper tissues also. However, if the symptoms produced are due 
to a direct action of the drug upon the blood, why, then, should there 
be such a long latent period in most cases? Furthermore, if the symptoms 
are due to a direct action of the drug upon muscles, glands, or abdominal 
organs, then these tissues should show histological changes; but the 
writer has failed to find anything more severe than a slight hyperemia, 
the cause of which may be easily explained on the basis of the hyper- 
activity of the organs concerned. 
