A six page letter from Keller Breland (coauthor of The Misbehavior of Organisms) to B F Skinner, (behaving organism), in 1961. Breland presents his approach to the interactions among environment, behavior and biological constraints, providing some interesting background on how the Brelands' work was related to Skinner's. Of course, instinctive drift is now a standard topic in behavior analytic texts.

My thanks to Bob Bailey for supplying these letters.