152 ANIMAL INTELLIGENCE. 



required three repeated lessons from Sir John before she 

 learnt that the window on the other side of the room, and 

 away from the direction of her nest, afforded no obstacle 

 to her exit. Having learnt this, the fourth time she 

 came she again flew to the closed window as before, and 

 then, as if but dimly remembering that there was another 

 opening somewhere that offered no such mysterious 

 resistance to her passage, ' she took two or three turns 

 round the room, and then flew out through the open 

 window.' Having now taken the bearings of all the room 

 upon her own wings, and having again found the difference 

 between the two windows in respect of resistance, although 

 in all other respects so much alike, the next time she 

 came she made in the first instance as it were an experi- 

 mental flight towards the closed window, but clearly had 

 the alternative of going to the open one in her memory ;; 

 for on finding the window closed as before, she did not 

 alight, but flew straight from the closed to the open window. 

 The same thing happened once again, but now, with 

 the distinction between the two windows thus fully learnt, 

 and with it the perception that in this case ' the short- 

 est cut was the longest way round,' she never again flew tO' 

 the closed window ; in the forty successive visits which she 

 paid through the remainder of that day, and the hundred 

 visits or so which she made during the two following days, 

 she seems to have uniformly flown to the open window. 



As evidence of forgetfulness, it will be enough to refer 

 to the case of another wasp which, under precisely similar 

 circumstances to those just detailed, learnt her way out of 

 the open window one day, having made fifty passages 

 through it in five hours. Yet Sir John remarks, — 



It struck me as curious that on the following day this wasp 

 seemed by no means so sure of her way, but over and over 

 again went to the closed window. 



It is further of interest to note, as showing the simi- 

 larity of the memory displayed by these insects with that 

 of the higher animals, that there are considerable indi- 

 vidual differences to be found in the degree of its 

 manifestation. 



