MODIFICATION OF THE BEHAVIOR OF LAND ANIMALS 47 



In all of the cases here discussed, except the reactions of the 

 wood frog to dry and moving air, and in most of the other ex- 

 periments, rapid modification took place. All the stimuli used 

 are those commonly encountered by the animals experimented 

 upon, in their natural environments. It is impossible to deter- 

 mine, however, in the case of animals collected and brought into 

 the laboratory, how much of this ability to avoid disadvantageous 

 stimuli has been acquired during the life of the individual. We 

 note that plants, which respond to environmental changes by 

 variations in growth form, show a similar relation to the various 

 stimuli. Those commonly encountered in nature usually call 

 forth advantageous responses, while those not usually encountered 

 call forth responses which are often decidedly disadvantageous. 

 Here this quality could not have been acquired by the individual 

 in its life experiences and is accordingly to be considered as an 

 innate capacity. It is, therefore, a fairly safe assumption that 

 the capacity to avoid disadvantageous stimuli, and the capacity 

 for advantageous modification, are innate also. Such capacities 

 appear to be common. The difference in the speed with which 

 frogs learn to avoid distasteful food as compared with the time 

 required for them to learn a maze or the presence of a glass 

 plate is a further example of the difference between reactions 

 to natural and unnatural stimuli and problems. As a further 

 example, we note the difference between the apparent "stupidity" 

 of the frog in failing to learn not to snap at a fly when the punish- 

 ment was the pricking of the upper jaw by a pin or needle 

 (Holmes, '11) as compared with the rapid learning to discriminate 

 between the kinds of food presented when certain kinds brought 

 punishment through the taste organs (Schaeffer, '11), the more 

 usual channel for disturbing results of food taking. The raccoon 

 is slow with a man's problem, such as a latch and door problem ; 

 what could he do with a forest and hollow tree problem the first 

 time it was presented to him ? What could a man do with a 

 forest and hollow tree problem ? That with some such problems 

 he errs widely and loses his way often, we are well aware. The 

 use of problems which the animals concerned could never by any 

 possibility have encountered is legitimate, and indeed a necessity 

 if the effect of experience is to be eliminated in animals not bred 

 for experimental purposes. Still, is not the degree of intelli- 

 gence shown by an animal, with its first problem of a kind 



