The Dawn of Reason Part 4

If the back of an earthworm be examined with a high-power lens (500), small points of pigment will be seen here and there in its dorsal integument; these, I believe, are primitive eyes (ocelli). I think that the worm is enabled to tell the difference between light and darkness through the agency of these minute dark spots, which serve to arrest the rays of light, thus conveying a stimulus to nerve-fibrils, which, in turn, carry it to the sensorium.

Any country schoolboy will tell you that worms can hear. He points to his simple experiment (pounding on the earth with a club) in proof of his a.s.sertion. For, as soon as he begins to pound the ground in a favorable neighborhood, the worms will come to the surface "to see what makes the noise." Darwin a.s.sumes that the worms feel the vibrations, which are disagreeable to them, and come to the surface in order to escape them. I do not deny the possibility or the probability of this a.s.sumption; I do deny, however, that it proves that worms are deaf.

If the third a.n.a.l segment (abdominal aspect) of a worm be examined, two round, disk-like organs incorporated in the integument will be found; these organs are supplied with special nerves which lead to the central nerve-cord. Experiments lead me to believe that these are organs of audition.

When I tap the earth of my vermicularium with a pencil, the unmutilated worms will come to the surface; but, when the organs described above are removed, the worms so mutilated will not respond to the tapping, but will remain in their tunnel. The worms are not appreciably impaired by such mutilation; on the contrary, they seem to thrive as well as those to which the knife has not been applied.

In creatures which possess, in all probability, the senses of touch, taste, smell, sight, and hearing, we would naturally expect to find some evidences of conscious determination; and we do.

Certain leaves are the favorite food of earth-worms, while certain other leaves are eaten by them, but not with avidity. When these two kinds of leaves are given to worms, they will carefully select the favorite food and will ignore the other, thus unmistakably evincing conscious choice.

Their avoidance of light is probably the result of conscious determination, and not reflex, as some observers maintain.

Oysters taken from a bank never uncovered by the sea, open their sh.e.l.ls, lose the water within, and soon die; but oysters kept in a reservoir and occasionally uncovered learn to keep their sh.e.l.ls closed, and live much longer when taken out of the water. This is an act of intelligence due directly to experience without even the factor of heredity.[33] It is an instance of almost immediate adaptation to surrounding circ.u.mstances.

[33] Dicquemase, _Journal de Physique_, Vol. XXVIII. p. 244; quoted also by Darwin, MS.; by Bingley, _Animal Biography_, Vol. III. p. 454; and by Romanes, _Animal Intelligence_, p. 25.

A gentleman fixed a land-snail, with the mouth of the sh.e.l.l upward, in a c.h.i.n.k of a rock. The animal protruded its foot to the utmost extent, and, attaching it above, tried to pull the sh.e.l.l vertically in a straight line. Then it stretched its body to the right side, pulled, and failed to move the sh.e.l.l. It then stretched its foot to the left side, pulled with all of its strength, and released the sh.e.l.l. There were intervals of rest between these several attempts, during which the snail remained quiescent.[34] Thus we see that it exerted force in three directions, never twice in the same direction, which fact shows conscious determination and no slight degree of intelligence.

[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 s.p.a.ce 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.

CHAPTER III

MEMORY

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._).

_Memory of Locality._--There can be no doubt but that the rhizopods observed by Carter displayed memory of locality. He distinctly a.s.serts that he saw the actinophrys, after it had incepted a starch grain, "crawl away to a good distance" and then return to the spore-cell from which it was taking the grains of starch. The creature must have remembered the route to and from the spore-cell. The same must be said of the water-louse observed by myself, which not only came back to the source of its food-supply, but also returned to a certain lurking-spot at which it hid itself each time until it had eaten the hydra buds. It must be remembered that a journey of one inch, to these minute little creatures, is, comparatively speaking, an immense distance. Each grain of sand, each particle of decayed vegetable matter, etc., is, to these microscopic animalcules, a gigantic boulder, a mighty muck heap. These obstacles in the path undoubtedly serve as landmarks to the wandering myriads of microscopic animalcules.

It can be demonstrated that the snail has memory of locality. This creature is essentially a homing animal, as I will show in the chapter on Auxiliary Senses, consequently we would naturally expect to find it possessing memory of locality. An interesting observation by Mr.

Lonsdale, an English observer, which has been often quoted, clearly proves that this creature does possess this psychical function. Mr.

Lonsdale placed two snails in a small and badly kept garden. One of them was weak and poorly nourished, the other strong and well. The strong one disappeared and was traced by its slimy track over a wall into a neighboring garden where there was plenty of food. Mr. Lonsdale thought that it had deserted its mate, but it subsequently appeared and conducted its comrade over the wall into the bountiful food-supply of the neighboring garden. It seemed to coax and a.s.sist its feeble companion when it lingered on the way.[35]

[35] Darwin, _Descent of Man_, pp. 262, 263.

Marked bees and ants invariably return to places where they have found food-supplies, thus showing the possession of a memory of locality and route. It is very interesting to watch a marked ant during her journey back to her nest, after she has been carried away and placed among unfamiliar scenes and surroundings. At first, owing to her fright, she will dash away helter-skelter; but soon recovering, she will head in the direction of home, and moderate her pace until she creeps along at a very cautious and circ.u.mspect gait, indeed. Every now and then she will climb a tall gra.s.s-blade or weed and take observations. After a while she sees certain landmarks, and her speed becomes faster; soon the surrounding country becomes familiar, and she ceases to climb blades of gra.s.s, etc., now she is in the midst of well-known scenes, and at last she fairly races into her nest.

In this instance the ant is led at first by her sense of direction alone; as soon, however, as she comes to country which she has hunted over, and with which she is familiar, memory comes into play and the sense of direction ceases to act, or, if it acts at all, it acts unconsciously.

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 a.s.sistance 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 _Carabidae_ and _Cicindelidae_ 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 s.e.xual 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 circ.u.mscribed 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.

_Memory of Friends_ (_Kindred_).--This phase of mind in ants has been closely studied and graphically described by Sir John Lubbock. Most of his experiments and observations have been verified by myself, therefore the reader will pardon me if I quote freely from his valuable work, _Ants, Bees, and Wasps_.

The observations of Huber, Ford, Lubbock, and other observers declare that ants can remember and recognize their kindred after having been separated from them for several months. "Huber mentions that some ants which he had kept in captivity having accidentally escaped, met and recognized their former companions, fell to mutual caresses with their antennae, took them up by their mandibles, and led them to their own nests; they came presently in a crowd to seek the fugitives under and about the artificial ant-hill, and even ventured to reach the bell-gla.s.s, where they effected a complete desertion by carrying away successively all the ants they found there. In a few days, the ruche was depopulated. These ants had remained four months without any communication."[36]

[36] Huber, p. 172; quoted by Lubbock, _Ants, Bees, and Wasps_, p.

120; also by Kirby and Spence, _Introduction to Entomology_, Vol. III.

p. 66; also by Newport, _Trans. Ent. Soc._, London, Vol. II. p. 239.

On one occasion, I took ten _Lasius niger_ and confined them in a specially constructed formicary so that they could not possibly leave the nest. I supplied these colonists with a gravid queen, so they very quickly became satisfied with their new home. Four months thereafter, I put three of these ants, previously marked with a paint of zinc oxide and gum arabic, into their former nest. They were at once recognized by their kindred, which began to caress them with their antennae and to remove the paint from their bodies. In the course of a half hour, the paint had all been removed, and I lost sight of them among the other ants.

A month after the performance of this experiment, I took three marked ants from the parent nest and placed them in the new nest. They were at once recognized by the colonists, which received them, as it were, with open arms and began to cleanse their bodies by removing the paint. In both of these experiments the recognition appeared to be instantaneous; there was no hesitancy whatever.

On the other hand, when performing like experiments with _Lasius flavus_, it took the ants (on two occasions) some little time to recognize their kindred; when the marked ants were put into the nest they were at once seized by the other ants, which pulled them about the nest for some time. They were finally recognized, however, and the paint removed from their bodies by the busy little tongues of their kindred.

This would seem to indicate that _Lasius niger_ had a better memory than _Lasius flavus_; whether the failure of the latter to recognize their friends at once was due, however, to faulty memory or not, is a psychical problem that will, probably, never be solved.

Lubbock's experiments with _Myrmica ruginodis_ clearly demonstrate that these ants can recognize their kin. Says he:--

"On August 20, 1875, I divided a colony of _Myrmica ruginodis_ so that one half were in one nest, A, and the other half in another, B, and were kept entirely apart.

"On October 3, I put into nest B a stranger and an old companion from nest A. They were marked with a spot of color. One of them immediately flew at the stranger; of the friend they took no notice.

"October 18.--At 10 A.M. I put in a stranger and a friend from nest A.

In the evening the former was killed, the latter was quite at home.

"October 19.--I put one in a small bottle with a friend from nest A.

They did not show any enmity. I then put in a stranger, and one of them immediately began to fight with her."[37]

[37] Lubbock, _Ants, Bees, and Wasps_, p. 121 _et seq._

These experiments show that _Myrmica ruginodis_ recognize their kin at sight, and that they are able to remember and recognize one another after long separations.