THE NATURAL 



mouthful of mortar on the ideal dome of an absent nest: 

 then with instinct satisfied, sure of having assured her 

 posterity, she retires, she goes to die. One can get the 

 same result with the pelopee, and with other builders. 

 Processional caterpillars are accustomed to make long 

 trips in Indian file on the branches of their native pine- 

 tree, in search of food: if one place them on the rim 

 of a basin they will stupidly circulate for thirty hours, 

 without one of them having the idea of interrupting the 

 circle by going off at a tangent. They will die in their 

 track, stuck fast in obedience; when one falls another 

 steps into his place, the ranks close, that is all. Here are 

 the extremities of instinct, and to our great surprise they 

 are almost the same in an Indian of the great lakes and 

 in a processional pine caterpillar. 



But other cases of animal's instinct joining with free 

 intelligence, give examples of human sagacity. We have 

 seen these same mason bees and xylocopes and domestic 

 bees profit eagerly by a nest ready made, by a hole bored 

 in wood, by artificial combs set ready to take their 

 honey; the osmies, who lay in the stalks of cut reeds, in 

 which they arrange a series of chambers, accommodated 

 themselves under Fabre's guidance in glass tubes which 

 permitted the great observer to know them intimately. 

 Instinct is by turns as stupid as a machine and as intelli- 

 gent as a brain; these two extremes should correspond 

 with very ancient and very recent habits. It is certainly 

 but a relatively short time since the peasant's pruning- 

 bill began preparing cut reeds for the osmie; before that 

 time she constructed her nest, as she still does, in empty 

 snail shells or in some natural cavity. They are very 

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