CONCL USION. 235 



large niimbers in a similar fashion nnder like conditions, wliile 

 in the second class each act is an individual affair, as where a 

 single Avasp, uninfluenced in any way by the example of those 

 about it, displays unusual intelligence in grappling with the 

 affairs of life. Examples of the first class are found in sucli 

 modifications of instinct as are shown by Pelopacus and other 

 wasps in the character of their habitations. Pelopacus, instead 

 of building in hollow trees or under shelving rocks, as was the 

 ancient custom of the race, now nests in chimneys, or under 

 the eaves of buildings. "We have found T. ruhrociiwtum tak- 

 ing advantage of the face of a straw stack that had been cut off 

 smoothly as the cattle were fed through the winter. The same 

 power of adaptation is shown by Fal^re's experiment with Osmia, 

 in which he took two dozen nests in shells from a quarry, Avhere 

 the bees had been nesting for centuries, and placed them 

 in his study along with some empty shells and some hollow 

 stems. When the bees come out, in the spring, nearly all of 

 them selected the stalks to build in as being better suited to 

 their use than the shells. All of these changes are intelligent 

 adaptations to new modes of life, serving to keep the species in 

 harmony with its surroundings. The same thing may be seen 

 when a number of social Avasps work together to replace the roof 

 of their nest when it has been torn off. 



An instance of the second class is seen in one of our examples 

 of Pompilus marginatum. This species, while searching for a 

 nesting-place, leaves its spider lying on the ground or hides it 

 under a lump of earth, in either of which positions the booty 

 is subject to the attacks of ants; the wasp in question improved 

 upon the custom of her tribe by carrying the spider up into a 

 plant and hanging it there. We have now and then seen a 

 queen of PoUstes fiisca occupy a comb of the previous year in- 

 stead of building a new one for herself, showing a better mental 

 equipment than her sistere who were not strong minded enough 

 to change their M^ays and so built new nests alongside of un- 

 occupied old ones which Avere in good condition. In Bembeac 

 society it is good form to close the door on leavins; home, but 



