Three groups of pigeons were studied: controls, pigeons treated with cycloheximide and pigeons treated with actinomycine D. It was noticed that in the first group spontaneous activity increased during different trials and that learning was rapid. In the second group, spontaneous activity remained constant during sucessive experiments while learning improved slowly. In the third group, spontaneous activity gradually disappeared and learning was non-existant. There is a parallelism between spontaneous and operative behavior in the control groups as well as in the treated animals.