RESPONSES OF YOUNG TOADS 205 



animals respond to contact in another manner than that of the 

 death-feint . The body of the toad is spread out and closely pressed 

 against the bottom of the aquarium, and the lungs are rilled 

 with air until the animal becomes as wide as it is long. The 

 head is also bent downward and placed on the bottom of the 

 aquarium. As long as the animal retains this position it remains 

 motionless. Reactions similar to these may occur as responses 

 to a moving shadow or object, as for example the writer's hand 

 when it is reached into the aquarium to remove the young 

 toads. So that these are responses to both tactual and visual 

 stimuli. Dickerson (I.e., pp. 33-34, 86) also has drawn atten- 

 tion to this form of response in the toad. According to Holmes 

 (I.e., p. 32), 



"Frogs sometimes swell the body before being seized as if in antici- 

 pation of their capture, and they are especially apt to do this after being 

 lightly touched. Touch a frog that is resting quietly, and if the creature 

 does not hop away, one may see the body puff up; and if the body is 

 touched two or three times, the swelling will continue until the lungs 

 contain their maximum amount of air. * * * Frogs often avoid 

 capture better by remaining perfectly quiet than by attempting to get 

 away by jumping. * * * Safety is also sought occasionally by crouch- 

 ing close to the ground, and more often by crawling under some object that 

 promises to afford shelter." 



Another interesting response to contact stimuli is the "sing- 

 ing" or croaking of frogs and toads. The croaking of frogs and 

 toads is readily induced by stroking the body, especially on 

 the back or sides. They also will croak when kept in an aquar- 

 ium. The contact of one animal against another is often suffi- 

 cient stimulus to produce this sound. It is not improbable that 

 light as well as contact may play some role in connection with 

 the croaking reflex. The writer frequently has observed hun- 

 dreds of toads in bright patches of moonlight along the shores 

 of ponds and marshes. On such occasions their heads are raised, 

 and the throat-sac is puffed out to a large size, owing to their 

 vigorous "singing." At such times they give little "attention" 

 to the observer, and one may pick up a toad, placing it upon 

 the palm of the hand where it will continue to "sing" with 

 astonishing vigor. 



IX. DISCUSSION 



It has been pointed out, in the experiments with the projec- 

 tion lantern, that young specimens of Bufo americanus orient 

 in such a manner with reference to the light that the head points 



