78 
HALF HOURS WITH INSECTS. [Packard. 
small a quantity so startling an effect; and it is, in fact, not 
so much to the venom of the dart as to the physiological 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 tegs, 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-thorax, though 
generally separate, are in some species united. Now 
it is a well-known fact that, in most cases, the more 
closely the nervous system is united, centralized as it were, 
the 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 
perform 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 Scaraboei, Buprestes and Curculionidae, the 
effect of his experiments was instantaneons; 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 three Tveeks or a month, 
preserving the flexibility of all their joints, and the normal 
freshness of their viscera.” 
14 
