In art, as in biology, there is a phenomenon that can be described as mutation, in which appearances radically change at a tempo much more rapid than that at which they normally proceed. As in the case of biology, we have no means to determine the process by which this radical change occurs. Yet we do know that it is a reaction to a form of congestion. It is a desperate change due to the arrival at a point where the corollaries to a situation are exhausted, when the stimulus to additional growth is sluggish and a rapid rejuvenation is needed so that art, through disuse, does not atrophy in much the same way as an unused human organ. Here art must attain a new start if it is to survive. Then, assiduously, it renews its traditions by marriage with alien traditions, by the reexamination of its own processes, and by those means reestablishes contact again with its own roots. It is in this way that new plastic worlds are born. For art, like a race, cannot inbreed very long without losing its incentives to continue; it needs the rejuvenation of new experiences and new blood. These mutations, it must be clear, however, do not constitute a change in properties, or mean that art has discarded its past. On the contrary, mutation involves a more conscious evaluation of art’s inheritance and the redirection of that inheritance into channels where it can be continued with greater force.