PHYSIOLOGICAL ACTION OF NITROBENZENE VAPOR ON ANIMALS 467 
is itself converted into anilin. Filehne has shown also that the theory 
of slow absorption does not account for the rapid action of the drug 
observed in certain cases. 
In all probability the rate of absorption of nitrobenzene by the body 
tissues does have something to do with the cause of the latent period; 
but the explanation must be primarily based on the readiness with which 
the drug is absorbed by certain tissues as compared with other tissues, 
and not alone on the rate of absorption by the tissues in general. It will 
be recalled that nitrobenzene is readily soluble in oils and the liquid fats; 
‘it is soluble also to a certain extent in lipoids, but probably to a less extent 
in certain lipoids than in others, and even the same lipoid may absorb 
the drug more readily under certain conditions than under other con- 
ditions. 
When the drug is administered by vapor inhalation, the amount 
absorbed by the blood (at a given vapor pressure) depends, undoubtedly, 
on the amount and the condition of the fats or the lipoids in the blood. 
Also, the amount absorbed from the blood and held in solution by the 
body fats is, in all probability, directly proportional to the absorption 
power of the body fats over the absorption power of the fats in the blood. 
Since nitrobenzene is more readily absorbed by the liquid body-fats 
than by the lipoids (of the brain), large amounts of it may be stored in 
the liquid fats of the body without the animal’s showing any immediate 
symptoms of poisoning. Moreover, since the action of the drug on the 
cells of the brain probably depends on its concentration in the vicinity of 
these cells —as in the case of chloroform, ether, and other drugs that 
act directly on the cells of the brain — nitrobenzene, depending on the 
amount and the condition of the lipoids and the fats held in suspension 
in the blood, may be picked up from the body fats by the blood in such 
small amounts as to be in time entirely eliminated from the body without 
ever giving a sufficient concentration in the vicinity of Purkinje’s cells 
to cause symptoms of poisoning; so that large amounts of the drug may 
be stored in the body without the animal’s ever showing any symptom 
of poisoning. 
On the other hand, depending on the concentration of nitrobenzene in 
the blood supply to the cerebellum, a sufficient concentration of the drug 
in the vicinity of the Purkinje cells might be reached, even after minute 
