25 26 3" 8" 44" 18" 26 19" 1" 176" 98" 58" 27 27 150" 79" 269" 166" 28 26" 3" 31" 20" 93" 29 28 214" 18" 267" 166" 30 40" 3" 4" 16" 91" 31 29 130" 45" 250" 142" 32 12" 3" 25" 13" 77" 33 Dec. 2 61" 35" 44" 47" 34 50" 5" 24" 26" 36" 35 3 66" 18" 2" 29" 36 8" 5" 10" 8" 19" 37 4 9" 4" 3" 5" 38 10" 5" 6" 7" 6" 39 5 5" 3" 5" 4" 40 10" 4" 3" 6" 5" One of the most interesting and important features of the behavior of the dancer in the ladder experiment was a halt at a certain point on the ladder. It occurred just at the edge of the wooden box at the point where the ladder took a horizontal position, and led over into the cage. Every individual from the first test to the last made this halt. Although from the point of view of the experimenter the act was valueless, it may have originated as an attempt to find a way to escape from the uncomfortable position in which the animal found itself on reaching the top of the ladder. Its persistence after a way of escape had been found is an indication of the nature of habit. Day after day the halt became shorter until finally it was little more than a pause and a turn of the head toward one side of the ladder. I think we may say that in this act we have evidence of the persistence of a particular resolution of physiological states which is neither advantageous nor disadvantageous to the organism. Had the act resulted in any gain, it would have become more marked and elaborate; had it resulted in injury or discomfort, it would have disappeared entirely. I have observed the same kind of behavior in the frog and in other animals. What the animal begins to do it persists in unless the act is positively harmful or conflicts with some beneficial activity. The only explanation of certain features of behavior is to be found in the conditions of their original occurrence. They persist by sheer force of conservatism. They have value only in the light of the circumstances under which they first appeared. Although this is merely a fact of habit formation, it suggests that many of the problems which have puzzled students of behavior for ages may be solved by a study of the history of activity.