^326 ASA A. SCHAEFFER 



there is the added danger that the disagreeable object may be 

 swallowed accidentall3^ (Disagreeable foods are usually con- 

 sidered harmful.) It is therefore highly advantageous to frogs 

 to learn rapidly to avoid disagreeable foods. 



On the other hand, the occasions must be rare when a frog 

 must hop over a transparent plate or thread a natural or arti- 

 ficial labyrinth correctly in order to achieve safety, or for any 

 other reason. Such opportunities could arise only when the 

 young frog leaves the native pond in search of some other pond, 

 or when the frog is compelled to leave the adopted pond on 

 account of its drying up, or for other reasons. From this it 

 follows that there could be little advantage in the ability to 

 learn rapidly to thread a simple labyrinth. From the stand- 

 point of natural history, such a capacity could hardly be con- 

 sidered as having life and death ^'alue ; it would be merely 

 an ornamental psychic quality. 



These considerations lead to what the author believes is the 

 real cause for the varying capacity of frogs to form different 

 habits. The author believes that the difference is to be sought 

 in the nervous equipment available in forming particular habits. 

 The fact that the feeding instinct is very complex, involving 

 many muscular actions and sense impressions all delicately 

 co-ordinated, bespeaks, according to the commonly accepted 

 teaching in such matters, an inherited neuro-muscular apparatus 

 which at the first proper stimulus works effectively. For the 

 green frog, and perhaps for all the others mentioned in this 

 paper, perhaps no two stimuli are exactly alike, even in the 

 whole life of the frog. Many sorts of insects and other animals 

 are eaten in many different positions; so that the feeding in- 

 stinct, although complicated, probably works extremely seldom 

 in exactly the same way. Instead of being a stereotyped in- 

 stinct or chain-reflex, the feeding mechanism is in reality very 

 plastic, and the fact that it is plastic suggests what is in all 

 probability the basis for the rapid formation of habits involving 

 the feeding mechanism. On the other hand, the relatively 

 long time required to learn the labyrinths of Yerkes is doubtless 

 due to the absence of a neuro-muscular mechanism formed 

 especially for learning rapidly a natural or artificial labyrinth. 



We may suggest as a tentative hypothesis that a habit may 

 be formed rapidly or slowly in proportion to the high or low 



