[40] _Sammlung physiologischer Abhandlungen_, Zweite Reihe, Erster Heft, 1878. [41] H. C. McCook, _American Spiders_ (1889, etc.), vol. ii. pp. 437-445. Romanes has an interesting discussion of the habit of feigning death among animals, and cautiously reaches the conclusion that it is very largely due, not to kataplexy, but to intelligent action.--_Mental Evolution in Animals_, pp. 303-316. And for some remarks on this subject by Darwin in his Essay on Instinct, see the same volume, pp. 365, 366. Also Alix, _Esprit de nos Betes_, 1890, pp. 543-548. Among fish, the Perch and the Sturgeon feign death; according to Couch,[42] the Landrail, the Skylark, the Corncrake adopt the same device. Among mammals, the best-known example is probably the Opossum. [42] _Illustrations of Instinct_, 1847. An Opossum (_Didelphys azarae_) of South America enters farms to devastate the poultry yards. When he is discovered he runs away, but is soon caught, and blows from sticks rain upon him. Seeing that he cannot escape correction he seeks at least to save his life. Letting his head fall and straightening his inert legs he receives the blows without flinching. Often he is considered dead, and abandoned. The cunning little beast, who desires nothing better, arises, shakes himself, and rather bruised, but at all events alive, takes his way back to the wood. The Argentine Fox (_Canis azarae_), when caught in a trap or run down by dogs, though it fights savagely at first, after a time drops down and apparently dies. "When in this condition of feigning death," Mr. W. H. Hudson remarks, "I am quite sure that the animal does not altogether lose consciousness. It is exceedingly difficult to discover any evidence of life in the opossum, but when one withdraws a little way from the feigning fox, and watches him very attentively, a slight opening of the eye may be detected; and, finally, when left to himself, he does not recover and start up like an animal that has been stunned, but slowly and cautiously raises his head first, and only gets up when his foes are at a safe distance. Yet I have seen _guachos_, who are very cruel to animals, practise the most barbarous experiments on a captive fox without being able to rouse it into exhibiting any sign of life. This has greatly puzzled me, since, if death-feigning is simply a cunning habit, the animal could not suffer itself to be mutilated without wincing. I can only believe that the fox, though not insensible, as its behaviour on being left to itself appears to prove, yet has its body thrown by extreme terror into that benumbed condition which simulates death, and during which it is unable to feel the tortures practised on it. The swoon sometimes actually takes place before the animal has been touched, and even when the exciting cause is at a considerable distance."[43] [43] W. H. Hudson, _Naturalist in La Plata_, p. 203.