324 ASA A. SCHAEFFER 



pillars persisted partially for ten days, for on the tenth day a 

 single trial again perfected the habit. In this case the habit 

 was severely tested by keen hunger resulting from lack of food 

 for two days. The other frogs also showed the effects of the 

 habit for similar periods of time. In the first series of experi- 

 ments the hairy caterpillar was refused while more than twenty 

 widely different kinds of insects, etc., were eaten. In the second 

 series, earthworms were refused while mealworms only were 

 eaten. Whether the eating of a large variety of animals tends 

 to break dow^n a habit of rejecting one kind sooner than the 

 eating of only a single variety would, has not been determined, 

 i The avoiding habits were formed in two different ways. First, 

 the disagreeable object was taken into the mouth and then 

 rejected, as in the case of avoiding hairy caterpillars. Second, 

 the disagreeable object was eaten without any visible effort 

 at rejection with the tongue. This involves no. muscular efforts 

 of a rejecting character. The habit is formed wholly in nervous 

 tissue. Habit formation of this character is illustrated in the 

 experiments with chemically treated earthworms. In the case 

 of Rana clamata (medium) the habit of avoiding earthworms 

 was formed on the basis of a single experience with a disagree- 

 able earthworm, which was eaten without any apparent effort 

 to eject it after it was in the frog's mouth, nor was there any 

 muscular effort observed that was not present when a normal 

 earthworm is eaten. 



'Although such a distinction does not seem to have been 

 brought out before by students of animal behavior, the prac- 

 tical value of such a distinction is apparent, for in experimenting 

 with animals, a habit might sometimes be thought to have 

 arisen suddenly when as a matter of fact it may have been 

 formed gradually and invisibly, and only made its appearance 

 suddenly. This may be illustrated by referring to the behavior 

 of the large Rana clamata. When did the earth worm-avoiding- 

 habit begin to form? Was it when the first chemically treated 

 earthworm was eaten, or was the habit actually initiated when 

 the electric shock was introduced — the chemically treated earth- 

 worm previously eaten having left no effect? Further, such 

 a discrimination enables us to conclude that actual trial with 

 subsequent rejection in unnecessary for the formation of a 

 habit based on the avoidance of a disagreeable object; trial 



