NOVEMBER 263 



postulate reasoning power, yet it would seem preposterous 

 to grant in a little sand wasp what we are compelled to 

 disbelieve in the highly organised vertebrates. Dr. Peck- 

 ham watched the wasp in question digging a hole in the 

 earth, depositing therein an egg, together with a spider, 

 which she had stung into paralysis, to feed the grub 

 which should be hatched in due course. Then she filled 

 up the hole with sand or earth, jamming it down with her 

 head. 



'When at last the filling was level with the ground, she 

 brought a quantity of fine grains of dirt to the spot, and, pick- 

 ing up a small pebble in her mandibles, used it as a hammer in 

 pounding them down with rapid strokes, thus making this spot 

 as hard and firm as the surrounding surface. Before we could 

 recover from our astonishment at this performance, she had 

 dropped her stone and was bringing more earth, and in a 

 moment we saw her pick up the pebble and again pound the 

 earth into place with it. Once more the whole process was 

 repeated, and then the little creature flew away.' 1 



The whole of this performance is so unexpected, so 

 little in accord with the manifestation of the uncon- 

 scious impulse which we define as instinct, that even Dr. 

 Peckham's high reputation as a scrupulous observer 

 might fail to convince sceptics that he had not been 

 deceived ; but similar behaviour on the part of a wasp 

 of the same species has been recorded independently by 

 Dr. Williston, of Kansas University. 



Another resort to mechanical aid has been described 

 by more than one independent observer, this time on the 

 part of a co-operative or social insect. An Asiatic ant 

 (Ecophylla smaragdina) makes a house by curling up 



1 Peckham's Instinct, etc., of Solitary Wasps, p. 22. 



