BIOPSYCHOLOGICAL 625 



If an instinctive capacity implies, on its physiological side, the 

 gradual elaboration of a number of neuro-muscular linkages, 

 activated by particular stimuli of vital importance, we can under- 

 stand its characteristic limitation that it ceases to work well when 

 there is some upsetting change in the circumstances. 



If instinctive behaviour implies the hereditary or racially estab- 

 hshed neuro-muscular prearrangements for a series of reflex actions, 

 in which a serves in part to activate b, and h does the same for c, 

 and so on, then the higher animals of the big-brained type do not 

 show very much of it. Educability and instinctive capacity are in 

 inverse ratio. A chick usually degenerates into an over-domesticated 

 hen; but it is in its youth alertly intelligent and astonishingly quick 

 to learn. With this is associated a paucity of instincts in the zoo- 

 logical sense. If hatched out in an incubator it does not recognise 

 its mother's call when she is brought outside the door of the room ; 

 it does not recognise water as water, although it walks through a 

 saucerful and will greedily swallow if a drop suspended from a 

 finger-tip is brought into touch with its bill; it will stuff its crop 

 with unprofitable worms of red worsted! But these and a score of 

 other significances are very rapidly learned. 



Extraordinary "Devices". — The suggestion of intelligence, as 

 distinguished from inborn instinct, sometimes comes from the 

 extraordinary subtlety of what the animal does. A spider's beautiful 

 web commands our admiration, but it is almost demonstrably 

 instinctive — made true to type the first time and made sometimes 

 in the dark; and there are more striking feats than making a web. 

 Longman describes a Queensland spider called "the Magnificent" 

 because of the particularly fine colouring of the female. But it is her 

 way of catching moths that interests us most at present. She hangs 

 down from a line and spins a thread about an inch and a half in 

 length, bearing at the free end a globule of very viscid matter, a 

 little larger than the head of a pin. The thread is held out by one 

 of the front legs, and on the approach of a moth the spider whirls the 

 thread and the globule with surprising speed. The moth, which seems 

 to be attracted, is struck, caught, pulled in, killed, and sucked. 

 When it is touched by the whirling globule, it is as helpless as a fly 

 on fly-paper. The ingenuity and originality of the device cannot but 

 arouse our admiration; we may well say of the Magnificent Spider 

 "c'est magnifique!"; but how difficult to think over the performance 

 without giving the creature credit for controlHng awareness! 



A very interesting fact, confirming the induction that good brains 

 run in families, is the recurrence of somewhat similar behaviour in 

 a related South African species of spider, also handsome and large 

 in its female expression. To a horizontal line the female spider fixes 

 a thread of silk with a viscid globule at the free end, and this is 

 held out by the third or shortest leg. But, unlike its Australian 

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