  Using an analytical model for the string network we show that the kurtosis of
cosmic microwave background (CMB) temperature gradient maps is a good statistic
to distinguish between the cosmic string model and inflationary models of
structure formation. The difference between the stringy and inflationary value
for the kurtosis is inversely proportional to the angular resolution and to the
number of strings per Hubble volume of the strings' scaling solution. If
strings are indeed responsible for CMB anisotropies then experiments with
resolutions of a couple of arcminutes or smaller could determine it using this
statistic.
