ADAPTATIONS TO SPECIAL ENDS 155 



and terrify such animals as will venture to attack venomous 

 serpents. Some confirmation is afforded to this theory by the 

 circumstance that rattlesnakes, unlike other serpents, do not 

 hiss. The noise of the rattle thus appears to serve the same 

 purpose as hissing ; and if the latter be for the purpose of 

 frightening enemies, the same will clearly be the case with the 

 rattle, which will consequently come in the category of defen- 

 sive adaptations. It should be observed, however, that the hiss 

 of a snake is regarded by some as a sign of fear and not of 

 defiance, although even then its result is probably the intimida- 

 tion of enemies. More important is the objection that the 

 sound of the rattle would apparently be quite as likely to 

 attract foes as to disperse them ; and in this connection it may 

 be mentioned that the sound of the rattle of one snake is 

 reported to cause all the rattlesnakes within hearing to set their 

 own apparatus in motion. Another theory, namely that the 

 rattle is for the purpose of attracting noisy insects such as 

 cicadas and grasshoppers within striking distance, by their mis- 

 taking the sound of the rattle for the " music " of their own 

 kind, seems sufficiently refuted by the fact that rattlesnakes 

 do not feed on insects. 



That the death-feigning instinct, so common among mam- 

 mals and insects, is not unknown among reptiles, appears to be 

 proved by the behaviour of an American hog-nosed snake 

 (Heterodon platyrhinus) described by an American naturalist in 

 1 907. When this snake is alarmed, it flattens its head and neck, 

 puffs out its body, and begins to hiss. Should these intimidating 

 efforts fail to frighten away the enemy another plan is tried. 

 The reptile throws itself into violent contortions, during which 

 the remnants of its last meal are in many instances vomited, 

 x^fter continuing for a few minutes, these writhings gradually 

 diminish in intensity until the snake lies inert on its back, as if 

 defunct. In this posture the reptile may remain from a few 

 seconds to many minutes, the instinct to simulate death being 

 so strongly developed that if the inert body be turned over to 

 the normal position the snake immediately returns to the 

 deadliest attitude at its command. Whenever the spasmodic 

 paroxysms reach the contortion stage, the series of actions is 

 continued to the end. Young snakes usually cease the per- 

 formance after a few seconds, but old ones will frequently feign 



