Introduction 



enemy. This makes it almost invisible, because of the likeness 

 of its skin in colour and texture to the soil. Many of the Salientia 

 play dead in response to an unexpected tactual stimulus. The 

 common toad will often hold the legs tight against the body and 

 inhibit all movement — even the breathing vibrations of the 

 throat — when seized by a dog or other enemy. The leopard 

 frog may stretch the legs backwards stiflf and straight, fold the 

 arms on the breast, and inhibit the breathing movements. It 

 certainly looks like a dead frog as it lies motionless in one's hand 

 for fully a minute; suddenly with a lightning movement it is 

 gone before the hand can be closed over it. The cricket frog 

 plays dead in water. Taking a position with arms and legs rigid 

 and throat collapsed, it floats about helplessly like any stick or 

 leaf. 



A very different protective instinct is possessed by some 

 members of the group. For instance, the gopher frog of Florida 

 has a ludicrous method of spasmodic instead of continuous ac- 

 tivity. When trying to escape an enemy, it remains motionless 

 for some seconds, after which it moves a short distance with 

 indescribable swiftness and stealth, and then appears statuesque 

 again in a new spot. This is repeated several times till the frog 

 is two or more feet from the enemy, when a few successive pro- 

 digious leaps take him far out of reach. The tree frog Hyla evit- 

 iaia, when startled, may leap to a twig and take a position be- 

 hind it. Here, hugging the twig closely, it will keep out of the 

 range of vision of the enemy by moving alternately back and 

 forth, to the right when the enemy moves to the left, and vice 

 versa. This instinct is probably possessed by many of the tree 

 frogs, though observed in this one only. 



On the whole, it would seem that frogs and toads possess 

 but a low order of intelligence. There are but few glimmerings 

 of anything above automatic response to stimuli, behaviour 

 resulting from reflex actions and hereditary instincts. They 

 certainly form crude ideas of food and enemies. They evidently 

 associate certain stimuli with crude ideas, such as the coming 

 of an enemy or something to eat. It has been proved by ex- 

 periment that they may associate two kinds of stimuli: after 

 having received an electric shock on touching given wires, they 

 afterwards leap as soon as they touch the wires and before the 

 electric current is turned on. 



34 



