MAN 193 



favorable conditions every animal can learn by the trial- 

 and-error method. The one-celled Protozoa can improve 

 through practice their ability to avoid unfavorable situa- 

 tions. A single arm of the starfish, a single tentacle of 

 the sea anemone, can learn' independently of the rest 

 of the animal. Clams and snails adjust themselves to new 

 conditions, and the earthworm can learn in a few days 

 whether to turn left or right when in search of comfort. 

 Simple avoidance-reactions of one type or another are 

 quickly acquired by the snail, squid, octopus, and cock- 

 roach, while the fiddler crab can be taught to move in 

 the direction of its small claw, though its normal mode 

 of progression is in the direction of the large one. The 

 honeybee uses a sign language that involves 'symbolism,' 

 and wasps and ants, like bees, show considerable plas- 

 ticity in behavior. Fish, though not outstandingly versa- 

 tile, can be conditioned to color, form, and sound, and 

 the habit may be retained for several weeks, while carp 

 are well known for their capacity for training in respect 

 to feeding habits. Frogs and toads have a sense of place 

 and show homing reactions; they can learn to find their 

 way out of simple mazes and can remember the solu- 

 tion for periods of at least thirty days, and their breeding 

 season takes on, for the first time in vertebrate history, 

 the audible call of mate to mate. 



Memory of places and persons is demonstrable in 

 birds, and for over forty centuries man has been training 

 the falcon to retrieve her hving prey. It is beheved by 

 fanciers that the instinctive singing of the canary is im- 

 proved by auditory tutelage under a Hartz moimtain 

 maestro, and canaries brought up with nightingales tend 

 to copy the nightingale's song. It has been shown that 

 pigeons can coimt up to five, ravens and parrots up to 

 seven, by what might be called nonverbal thinking (that 

 is, thinking that excludes verbal enumeration and the 

 use of symbols) and this is about as good as man can 

 do, and probably better than the chimpanzee. In respect 

 to the ability to learn, however, the primates are superior 



