236 The Animal Mind 



ing of this species (216, Series I, 263). Bouvier, repeat- 

 ing Fabre's experiments on Bembex, obtained a different 

 result. When a stone, for example, that had been at the 

 mouth of a Bembex nest was moved a distance of 2 dm., 

 the wasp, returning, went to the stone. Bouvier accord- 

 ingly maintains the visual landmark hypothesis (99). 

 Ferton holds the same view with regard to a species of 

 wasp that makes its nest in shells. If during successive 

 absences on the wasp's part the shell is moved from posi- 

 tion A to position B, and later from B to C and from C to 

 D, the wasp, returning, goes in turn to each of the posi- 

 tions that the shell has occupied. "In time, she omits to 

 go to A, then to B. Little by little, the image of the pre- 

 vious locations of her nest is effaced in the insect's memory." 

 When she has found it, after each displacement, she makes 

 a new "locality survey," before starting off again (217). 



Turner (728) reports that the mason wasp is certainly 

 guided by visual landmarks. A wasp had built her nest 

 on a window casing. The window was one of four in a 

 row; the shades on the other three were down. When 

 the shade on the window where the wasp's nest was situ- 

 ated was drawn down and that of the next window drawn 

 up, the wasp returning sought her nest on the casing of 

 the next window, which was now the only light one in the 

 row. 



Solitary wasps and bees, which need to find their way 

 back, not to a nest whose position remains fixed, as is the 

 case with ants and honey bees, but to nests in new positions 

 from day to day, almost certainly have to depend upon 

 their recognition of visual landmarks, and hence we have 

 another evidence that the compound eye can give a ser- 

 viceable image. 



The migration of birds is still an unsolved problem. 



