Ten days after an attack I was unable to obtain the least vestige of susceptibility by the above process; and I then had recourse to the Voltaic battery. This method is more powerful and provokes muscular contractions and movements where the benzine-vapour fails. We have only therefore to apply the current of one or two Bunsen cells through the conductors of some slender needles. Thrusting the point of one under the farthest ring of the abdomen and the point of the other under the neck, we obtain, each time the current is established, not only a quivering of the tarsi, but a strong reflexion of the legs, which draw up under the abdomen and then straighten out when the current is turned off. These flutterings, which are very energetic during the first few days, gradually diminish in intensity and appear no more after a certain time. On the tenth day I have still obtained perceptible movements; on the fifteenth day the battery was powerless to provoke them, despite the suppleness of the limbs and the freshness of the viscera. To effect a comparison, I subjected to the action of the Voltaic pile Beetles really dead, Cellar-beetles, Saperdæ and Lamiæ, asphyxiated with benzine or sulphuric acid gas. Two hours at most after the asphyxiation, it was impossible for me to provoke the movements so easily obtained in Weevils who have already for several days been in that curious intermediate state between life and death into which their formidable enemy plunges them. All these facts are opposed to the idea of something completely dead, to the theory that we have here a veritable corpse which has become incorruptible by the action of a preservative fluid. They can be explained only by admitting that the insect is smitten in the very origin and mainspring of its movements; that its susceptibility, suddenly benumbed, dies out slowly, while the more tenacious vegetative functions die still more slowly and keep the intestines in a state of preservation for the space of time required by the larvæ. The particular thing which it was most important to ascertain was the manner in which the murder is committed. It is quite evident that the chief part in this must be played by the Cerceris’ venom-laden sting. But where and how does it enter the Weevil’s body, which is covered with a hard and well-riveted cuirass? In the various insects pierced by the assassin’s dart, nothing, even under the magnifying-glass, betrayed her method. It became a matter, therefore, of discovering the murderous manœuvres of the Wasp by direct observation, a problem whose difficulties had made Léon Dufour recoil and whose solution seemed to me for a time undiscoverable. I tried, however, and had the satisfaction of succeeding, though not without some preliminary groping.