[Model of an excitable medium in which may exist several stable impulses of different duration]

It is shown how with the help of minor changes of the type of non-linear function (corresponding for example to the current voltage characteristics of the active biological membrane) a non-monotonous relationship between the excitation pattern velocity and the value of the slow variable is obtained in a model of the excitable medium. In such a model several steady impulses may exist which propagate with equal velocity, but having different duration.