The Death- feigning Instinct. 201 



simulating instinct, though it is hardly possible to 

 believe that the action springs from the same im- 

 mediate cause in vertebrates and in insects. In the 

 latter it appears to be a purely physical instinct, the 

 direct result of an extraneous cause, and resembling 

 the motions of a plant. In mammals and birds it 

 is evident that violent emotion, and not the rough 

 handling experienced, is the final cause of the 

 swoon. 



Passing over venomous snakes, skunks, and a few 

 other species in which the presence of danger excites 

 only anger, fear has a powerful, and in some cases 

 a disabling, effect on animals ; and it is this para- 

 lyzing effect of fear on which the death-feigning 

 instinct, found only in a few widely-separated species, 

 has probably been built up by the slow cumulative 

 process of natural selection. 



I have met with some curious instances of the 

 paralyzing effect of fear. I was told by some hunters 

 in an outlying district of the pampas of its effect 

 on a jaguar they started, and which took refuge in 

 a dense clump of dry reeds. Though they could see 

 it, it was impossible to throw the lasso over its head, 

 and, after vainly trying to dislodge it, they at length 

 set fire to the reeds. Still it refused to stir, but lay 

 with head erect, fiercely glaring at them through the 

 flames. Finally it disappeared from sight in the 

 black smoke ; and when the fire had burnt itself out, 

 it was found, dead and charred, in the same spot. 



On the pampas the gauchos frequently take the 

 black-necked swan by frightening it. When the 

 birds are feeding or resting on the grass, two or 

 three men or boys on horseback go quietly to lee- 



