Sand-wasps build their nests in the ground, and, when leaving their tunnels in search of food for the prospective grubs, always circle about them and observe the lay of the land before taking their departure. Numerous sand-wasps build in the interstices between the bricks of a pavement in front of my house. When one leaves her tunnel she will fly about the orifice for several seconds (taking observations) before she finally flies away. When she returns, she hovers about the orifice, or, rather, in its neighborhood, until she is quite certain that it is the entrance to her home, when she will dart in with such rapidity that the eye can scarcely follow her movements.
On one occasion, I covered the pavement surrounding the entrance with newspapers, leaving, however, about three inches on all sides of the orifice uncovered. When the wasp returned she seemed to be completely at a loss what to do. She hovered about for at least an hour, and then flew away.
Thinking that this experiment was too great a tax on the wasp's intelligence, I tried the following, which seemed to me to be nearer a natural happening than the former experiment. I believe that, in studying mind in the lower animals, one's experiments should be as near nature as they can possibly be.
As soon as the wasp had left her tunnel, I covered the surface of the bricks and the interstices between them, for several feet around the orifice of the tunnel, with sand. This might have happened, naturally, through the agency of the wind.
When the wasp returned, it was perfectly apparent that she did not recognize her domicile. She flew here and there and round about, but she would not alight. Finally, I swept the sand away, when she at once flew to her nest and entered.
In my opinion, these experiments prove very clearly the presence of memory of locality in these insects. The sense of direction, which a vast majority of the lower animals possess in some degree, is, however, of material assistance to their memory; this special sense will be fully discussed in another chapter.
Most of the beetles are homing animals; that is, they have certain spots to which they will return after excursions in search of food. Heretofore, observers have held to the opinion that beetles made their homes wherever they happened to be; but close study of marked individuals, especially of Carabidæ and Cicindelidæ has taught me otherwise. Some of the long-horned beetles appear to be rovers, but these are always males, and their roving habits are due to sexual promptings. The females are, however, to a great extent, homing animals, and do not wander far after they have once established a home. Being creatures which recognize certain surroundings as home, they must, necessarily, have some memory of locality. This proposition is new, being formulated and advanced by myself alone, therefore I expect that it will be negatived by many investigators. All that I ask, however, is that marked specimens of the different genera be closely watched; I am confident that if this plan be followed, the truthfulness of this proposition will soon be universally acknowledged.
Reptiles and certain fishes are homing animals, and this habit is especially noticeable in the land or box terrapin. One of these animals had its home for many years in my lawn, and I have often satisfied myself in regard to its knowledge of locality. I have frequently taken it several hundred yards (its usual "using-place" is circumscribed at about one hundred yards) away from its home and set it free.
At first, led by its sense of direction, it would turn towards home and slowly crawl in that direction. It would not feed en route, but seemed intent only on arriving at its home as quickly as possible. Finally, when it arrived among familiar surroundings, it would begin to feed, but would still make its way homeward. It clearly and unmistakably indicated by its actions that it had a memory of locality.
This treatise on mind in the lower animals is, mainly, a study of psychical manifestations as they are to be observed in insects; therefore, the higher animals will only be studied incidentally. Suffice it to say that, among the higher animals, evidences of memory of locality are very abundant, and are so patent that they do not need discussion.