THE WKITINOS OP M. FAEEE. 125 



closely the nervous system is united, centralized as it were, tBe more 

 perfect are the animal functions, and also, of course, the more easily 

 vulnerable. Therefore the Cerceris, whose instinct teaches her at 

 one stroke to annihilate these functions, chooses her victims precisely 

 from the species in Avhich tliis centralization is most complete : the 

 Buprestes, namely, of which the nervous centres of the meso- and 

 met a- thorax are confounded in one large mass ; the Curculicnidre, of 

 whicli the three thoracic ganglia lie near together, the two last quite 

 contiguous to each other. 



The green larvae found by Ecaumur in the nests of his solitary 

 wasps {Ochjnerus spinipes) w^erefullof life, though apparently plunged 

 by some mysterious means into a state of lethargy: the simple expla- 

 nation of which is, that, in these creatures, the nervous system is more 

 cliftused over the body and consequently loss ail^cted by an attack at 

 any given point. It is, we must remember, of the greatest importance 

 to the Cerceris that her prey should be completely numbed and inca- 

 pable of the least movement : otherwise, what would become of the 

 precious egg laid among struggling Coleojitera ? what of the ten- 

 der little grub, which should emerge in the midst of their great horny 

 claws, writhing convulsively about in a narrow cell ? If she attacked 

 feeble and apathetic larvae, one can imagine that a less complete anni- 

 hilation of muscular action would suffice ; but in the case of beetles 

 twice her own size it woidd be worse than useless ; and she therefore 

 picks out, with imerring precision, from the numerous tribes of Co- 

 leoptera, two of those i)est calculated by the peculiarities of their 

 nervous system to be rendered thoroughly powerless. 



In order completely to establish his opinion, it remained for M. 

 Fabre to prove that he could by similar means produce a similar 

 result. And this he found himself able to perform with perfect ease, 

 by punctviring the insect with a needle dipped in ammonia at the 

 prothoracic joint, behind the first pair of legs. Any corrosive 

 liquid applied to the thoracic medullary centre Avould have the 

 same effect. His experiments were made in the first instance upon 

 LameUicorns (Scarabceus sacer, S, laticoUls) ; on Buprestes {B. 

 cenea), and on Curculionida?, especially on the particular species so 

 often previously examined by him. He afterwards tried his skill 

 upon Carabidte {Oarabus, Procustes, ChlcBiiius, SpJiodrus, Nehria, 

 &c.) ; upon Longicorns (^SaiJerda, Lamia), and upon Melasomas 

 {Blaps, Scaurus, Asida). In the case of Scarabrei, Buprestes, and 

 Ciu'culionidsp, the effect of his experiments was instantaneous: alb 

 motion ceased suddenly, without a single convulsion, at the instant 

 the fatal drop touched the medullary centre. Not the dart of the 

 Cerceris herself could have a more prompt or lasting effect. Not- 

 withstanding their complete immobility, M. Fabre's victims re- 

 mained alive for three weeks or a month, preserving the flexibility of 

 all theii" joints, and normal freshness of viscera. Digestion proceeded 

 for the first few days, and movements could be provoked by a voltaic 

 current. In the case of IScarabaJus, however, this state cannot always 



