[34] Consult Romanes, _Animal Intelligence_, p. 26.
A ground wasp once built a nest beneath the brick pavement in front of my door. The entrance of the nest was situated in the little sulcus, or ditch, between two bricks. While the wasp was absent, I stopped the entrance with a pellet of paper, and, when the little housekeeper returned, she was nonplussed for a moment or two, when she discovered that her doorway had been closed. The wasp, after examining the pellet of paper, seized it with her jaws and tried to pull it away; but, since she stood on the brick and pulled backwards (toward herself), the edge of the brick interposed, and she could not dislodge the obstacle. Finally, she got down into the little gully between the two bricks, and pulled the pellet away from the opening of the nest without any further trouble. Three times I performed the experiment, the wasp going through like performances each time. At the fourth time, however, she went at once into the little space between the bricks, and then removed the wad of paper without difficulty. I stopped the hole five or six times after this, but she had learned a lesson; she always got into the sulcus between the bricks before attempting to remove the paper. She had discovered the fact that she could not remove it when she stood upon the surfaces of the bricks, owing to the interposition of their sides, and that she could drag it away if she got down into the little ditch and pulled the paper in a direction where nothing opposed. In this instance there was not only conscious determination, but also a distinct exhibition of memory. It took the wasp some time to learn that she had to pull in a certain direction before she could remove the pellet of paper; but when she had once learned this fact, she remembered it. And this brings us to another quality of mind--memory--which will be discussed in the next chapter.
In discussing memory as it is to be observed in the lower animals, I think it best to divide the subject into four parts; viz., _Memory of Locality_ (_Surroundings_), _Memory of Friends_ (_Kindred_), _Memory of Strangers_ (_Other Animals not Kin_), and _Memory of Events_ (_Education_, _Happenings_, _etc._).