To choose as the spot in which to plant her sting the one vulnerable point, the point which only a physiologist versed in the anatomy of insects could determine beforehand is by no means enough; the Hymenopteron has a far greater difficulty to overcome, and she overcomes it with a mastery which fills one with amazement. We said that the nervous centres controlling the organs of motion in an insect are three. These are more or less distant from each other, but sometimes, though rarely, near together. They possess a certain independence of action, so that an injury to one does not cause, at all events immediately, more than paralysis of members connected with it, while the other ganglia and their corresponding members are not affected by it. To reach these three sources of motion one after the other, the second farther off than the first, and the last farther still, and by a single way, between the first and second pairs of feet, seems impossible for the sting, which is too short, and besides, so difficult to aim well in such conditions. True, certain Coleoptera have the three ganglia of the thorax almost touching, and others have the two last completely united, soldered, smelted together. It is also recognised that in proportion as the different nervous centres combine and centralise, the characteristic functions of animality become more perfect, and also, alas, more vulnerable. Those Coleoptera with centres of motion so near that they touch or even gather into one mass, and so are made part of each other, would be instantly paralysed by one sting; or if several were needed, at all events the ganglia to be paralysed are all collected under the point of the dart. Now which are the Coleoptera so specially easy to paralyse? That is the question. The lofty science of a Claude Bernard, floating in the fundamental generalities of organisation and life, is no longer enough for us; it is unable to inform and guide us in this entomological selection. I appeal to every physiologist under whose eye these lines may fall. Without having recourse to his book-shelves, could he name the Coleoptera where such a nervous centralisation is found, and even with the help of his library, could he instantly lay his hand on the information wanted? The truth is, we are entering on the minute details of the specialist; the highway is quitted for a path known to few.