Is it possible to define a subroutine to access generation number, population of the generation during the course of the "gamultiobj"?

My objective function derives from 2 variables both of whose values i need for further calculations. I cannot obtain it by plugging the result of the GA in the program. So, if it is possible to store the population of each generation, my work will be done. There are probably better methods, but cannot think of any now. Thanks in advance.