172 CREATIVE EVOLUTION [chap. 



As to the original theme, it is everywhere and nowhere. 

 It is in vain that we try to express it in terms of any idea: 

 it must have been, originally, felt rather than thought. We 

 get the same impression before the paralyzing instinct 

 of certain wasps. We know that the different species 

 of hymenoptera that have this paralyzing instinct lay their 

 eggs in spiders, beetles or caterpillars, which, having first 

 been subjected by the wasp to a skilful surgical operation, 

 will go on living motionless a certain number of days, and 

 thus provide the larvae with fresh meat. In the sting 

 which they give to the nerve-centres of their victim, in 

 order to destroy its power of moving without killing it, 

 these different species of hymenoptera take into account, 

 so to speak, the different species of prey they respectively 

 attack. The Scolia, which attacks a larva of the rose- 

 beetle, stings it in one point only, but in this point the 

 motor ganglia are concentrated, and those ganglia alone: 

 the stinging of other ganglia might cause death and putre- 

 faction, which it must avoid. 1 The yellow- winged Sphex, 

 which has chosen the cricket for its victim, knows that the 

 cricket has three nerve-centres which serve its three pairs 

 of legs — or at least it acts as if it knew this. It stings 

 the insect first under the neck, then behind the prothorax, 

 and then where the thorax joins the abdomen. 2 The 

 Ammophila Hirsuta gives nine successive strokes of its 

 sting upon nine nerve-centres of its caterpillar, and then 

 seizes the head and squeezes it in its mandibles, enough to 

 cause paralysis without death. 3 The general theme is 

 "the necessity of paralyzing without killing"; the vari- 

 ations are subordinated to the structure of the victim on 

 which they are played. No doubt the operation is not 



1 Fabre, Souvenirs entomologiques , 3 e sene, Paris, 1890, pp. 1-69. 

 * Fabre, Souvenirs entomologiques, l re serie, 3 e Edition, Paris, 1894, 

 pp. 93 ff. 



8 Fabre, Nouveaux souvenirs entomologiques, Paris, 1882, pp. 14 ff. 



