338 GENERAL ZOOLOGY 



drobates, the tropical toad whose secretions are used for arrow 

 poison, is bright green or pink, spotted with a dark color. On 

 the other hand, one of the most poisonous toads, Bufo marinus, 

 found widely distributed in the American tropics is drab-colored. 

 The rattlesnake, whose color pattern is well denned but not 

 particularly conspicuous, is provided with a warning mechanism 

 in the shape of its rattle. The copperhead snake, Agkistrodon 

 ■mokasen, colored an inconspicuous yellowish brown, is also 

 poisonous but lacks a rattle. It would seem to be entirely lacking 

 in any sort of warning adaptation. 



Warning adaptations may or may not be present in animals 

 that are provided with some noxious means of defense. Where 

 present, warning adaptations are to be regarded as primarily 

 for the protection and benefit of the possessor rather than its 

 enemies. While it is true of course that the lack of a warning 

 rattle makes the copperhead snake in some ways more dangerous 

 to man than the rattlesnake, a harmful animal is benefited by 

 announcing its presence, because it may thereby be relieved of 

 the necessity of risking battle. One or two experiments prob- 

 ably teach a bird to avoid unpalatable insects, with the result 

 that the latter as a whole are benefited, though some are killed. 

 This interpretation is supported by experiments showing that 

 hungry animals discriminate between palatable caterpillars and 

 other varieties. 



Signals. — It is thought that signals may play a part in the 

 protective mechanism of some animals, though there is consider- 

 able difference of opinion among biologists on this point. The 

 American antelope, Antilocarpa americana, an inhabitant of open 

 country in Western North America, has white hairs on the rump 

 which when spread flash a signal. The "cottontail" of the 

 rabbit Sylvilagus floridanus, which is so conspicuous when the 

 animal is running, is supposed by some to serve as a beacon for 

 the young to enable them to follow the parent in escaping from 

 danger. 



Feint.— Some animals, particularly insects and spiders, when 

 touched or held in the hand, become motionless. The death- 

 feigning posture is held for a short time and then the animal 

 resumes its usual activity. Several species of toads when 

 suddenly disturbed respond by bending back the head and twist- 

 ing both pairs of legs over the back of the body, leaving the 



