A new concept of differential for
a multifunction is introduced. Here by a multifunction we mean a map from a
Banach space X to some specified family of non void subsets of a Banach space Y .
The comparison with another definition due to Lasota and Strauss shows that if a
multifunction admits both differentials, these must be equal. The results are
applicable to the perturbation theory for multivalued differential equations in a
Banach space