An Analytical Approach to Fluctuations in Showers

We review the problem of fluctuations in particle shower theory. By using a generalization of Furry equation, we find relations between the $n$--particle correlation function and the number of particles average or 1--particle correlation function. Such relations show that the average is the only independent dynamical variable. We also develop a numerical code to solve the equation for the correlation functions and compare the results with those from a Montecarlo simulation which show a perfect agreement between both methods.