The Modern Theory of Instinct 



She does better than that. The victim's 

 head is still unscathed, the mandibles are at 

 work: they might easily, as the insect is 

 borne along, grip some bit of straw in the 

 ground and successfully resist this forcible 

 removal; the brain, the primary nervous 

 centre, might provoke a stubborn contest, 

 which would be very awkward with so heavy 

 a burden. It is well that these hitches should 

 be avoided. The caterpillar, therefore, 

 must be reduced to a state of torpor which 

 will deprive him of the least inclination for 

 self-defence. The Ammophila succeeds in 

 effecting this by munching his head. She 

 takes good care not to use her needle: she 

 is no clumsy bungler and knows quite well 

 that to inflict a mortal wound on the cervical 

 ganglia would mean killing the caterpillar 

 then and there, the very thing to be avoided. 

 She merely squeezes the brain between her 

 mandibles, calculating every pinch ; and, each 

 time, she stops to ascertain the effect pro- 

 duced, for there is a nice point to be achieved, 

 a certain degree of torpor that must not be 

 exceeded, lest death should supervene. In 

 this way, the requisite lethargy is obtained, 

 a somnolence in which all volition is lost. 

 And now the caterpillar, incapable of resist- 

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