79. Class gifts.

A limitation to a class is governed by the same principles as other limitations with respect to the rule against perpetuities, but the effect of the rule needs a separate statement. By a limitation to a class is meant1 a limitation to a number of devisees or alienees, uncertain in number at the time of the gift, to be ascertained at a future time, all or some of whom2 come within a certain category or description defined by a general or collective formula3, or within a number of such categories or descriptions4, who, if they are to take at