78 HALF HOURS WITH INSECTS. [Packard. 



small a quantity so startling an effect ; and it is, in fact, not 

 so much to the A-enom of the dart as to the phj^siological im- 

 portance of the exact point at which it enters, that we must 

 ascribe the cessation, so complete, so instantaneous, of all 

 active life, 



"In most insects there are three ganglia, which furnish 

 the nerves of the wings and legs, and on which the power of 

 movement principally depends. The first, that of the pro- 

 thorax, is distinct from the others in all Coleoptera ; but 

 the last two, those of the meso- and meta-thordx, though 

 generally separate, are in some species united. Now 

 it is a well-known fact that, in most cases, the more 

 closely the nervous sj'stem is united, centralized as it were, 

 tho 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 

 which this centralization is most complete. 



"In order completely to establish his opinion, it remained 

 for M. Fabre to prove that he could by similar means pro- 

 duce a similar result. And this he found himself able to 

 psrfoi'ra with perfect ease, by puncturing 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 would have the same effect. " His 

 experiments were made upon the grubs of various beetles. 

 "In the case of Scarabaii, Buprestes and Curculionldn?, the 

 effect of his experiments was instantaneous ; all 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 last- 

 ing effect. Notwithstanding their complete immobility M. 

 Fabre's victims remained alive for tSree weeks or a month, 

 preserving the flexibility of all their joints, and the normal 

 freshness of their viscera." 



U 



