1890.] President' '.? Address. xxiii 



tyrannus as they come out of their burrows. One is alighting on a 

 small mimosa-bush. She is not attracted by flowers, although the 

 bush is in blossom. She goes straight to a small bough where several 

 medium-sized caterpillars of a Bombycid are resting. She alights on 

 the back of one and seizes it behind the head with her mandibles. 

 The caterpillar objects evidently, raises the fore part of its long body ; 

 the long pedunculated abdomen of the Sphex is curved under the poor 

 creature. I stand underneath and have a very good view of it ; the 

 Sphex is evidently feeling her way with the last segment of her 

 abdomen ; all at once there is a contraction of the peduncle, and I see 

 the sting drawn out from the wound. The process is repeated lower 

 down this time, another segment is punctured. The abdomen is now 

 hidden from view. I must turn to see what has become of the Fphex. 

 There she is still on the back of her victim, whose struggles, however, 

 have partially ceased, busy munching the back of its head. Four or 

 five minutes have been sufficient for the completion of this drama. 

 The caterpillar now can with difficulty adhere to the branch ; it is 

 partly dragged and partly carried by its victor. After a long journey 

 the nest is reached. The Sphex abandons the caterpillar and enters 

 the den, re-issues, drags the caterpillar a little nearer, enters again, 

 stays inside a little longer than the first time, and at last grasps her 

 burden and enters with it. That Sphex has unawares given me a 

 lesson on the anatomy of the nervous system of the caterpillar. 



If you look at this diagram you will perceive that the nervous 

 system consists of two cords intersected by swellings (ganglia) from 

 which spread ramifications. This is really analogous to the spinal 

 cord of the superior animals. The brain is represented by several pairs 

 of ganglia massed together, and it is very probable that each of these 

 ganglia corresponds to the number of primitive segments which, fused 

 together, have formed the head. 



Now it may be said that each ganglion is adapted to each segment ; 

 still some of them have special functions ; in fact, during the metamor- 

 phosis some of them become partially absorbed, and their function is 

 more localised. If by means of an extremely fine needle I puncture 

 any of these ganglia, the segment becomes paralysed ; but if I touch 

 the cerebral ganglion, death ensues forthwith. 



The !>phex has not punctured the brain, oh no ! but its stiletto has 

 destroyed the 3rd, 4th, oth, and 6th ganglia, which supply the nerves 

 to the legs, the 7th, 8th, 9th, 10th, 11th and 12th which supply the 

 nerves to the long abdomen, and it has done so in a masterly fashion. 

 One might think that it would be much easier to puncture through the 

 back instead of twisting the abdomen and insert the stiletto underneath. 

 No, the Sphex is too good a physiologist to make such a grievous 

 mistake. She knows very well that the chain of ganglia lies on the 



