V ONE SKILFUL TO SLAY 71 



motive power at one blow. Therefore she must 

 direct her dart at the nervous centres, the source of 

 the power of motion whence radiate the nerves 

 running up to the various organs of movement. 

 Now these sources of locomotion, these nervous 

 centres, consist of a certain number of ganglia, more 

 numerous in the larva, less so in the perfect insect, 

 and arranged on the median line of the under 

 surface in a string of beads more or less distant and 

 connected by a double ribbon of nervous tissue. In 

 all insects which have reached the perfect state the 

 ganglia called thoracic, i.e. those, furnishing nerves to 

 wings and feet and governing their movements, are 

 three in number. Here are the points to be struck : 

 if their action can be in any way destroyed, the 

 possibility of movement is destroyed also. 



Two ways of reaching these motive centres offer 

 themselves to the feeble dart of the Hymenopteron ; 

 one, the joint between neck and corslet ; the other 

 the spot where the latter joins the continuation of 

 the thorax, between the first and second pair of 

 feet. The way through the neck does not answer ; 

 it is too far from the ganglia, which lie near the base 

 of the feet which they animate. The blow must be 

 dealt at the other spot, and through that only. 

 Thus would an academy decide where Claude 

 Bernards illuminated the question by their profound 

 science. And it is precisely there, between the first 

 and second pairs of feet on the median line of the 

 under surface, that the Cerceris plunges her lancet. 

 By what learned intelligence must she be inspired ! 



To choose as the spot in which to plant her sting 

 the one vulnerable point, the point which only a 



