  We discuss the question whether the matter in dusty tori around active
galactic nuclei has a smooth or a clumpy structure. Nenkova, Ivezic & Elitzur
(2002) have argued that the lack of emission feature in the SEDs of type 1 AGN
galaxies combined with a clear absorption feature in type 2 AGN can be
explained if the circumnuclear dust is distributed in discrete clumps. Our aim
is to verify this. We use multi-dimensional radiative transfer models of smooth
and clumpy tori, and compare the SEDs of equivalent smooth and clumpy models.
We find that the 10 micron emission feature of the clumpy models, when seen
almost face-on, is not appreciably reduced compared to the equivalent smooth
models. Some of the clumpy models have a weak or even absent 10 micron feature,
but so do some of the smooth models. On the whole the SEDs of clumpy and smooth
tori are similar, but some details are different. The absorption feature seen
at edge-on inclinations appears to be less deep in the clumpy models than in
the smooth models, and the average flux in the near-infrared regime is stronger
in the clumpy models. Moreover, at these inclinations the clumpy models have a
slightly wider SED. Whether these differences are unique enough to be used as a
diagnostic for clumpiness of AGN tori is not yet clear.
