Kitabı oku: «Lippincott's Magazine of Popular Literature and Science, Vol. 22, November, 1878», sayfa 4

Percival found that the debt was a small one, and calculated that by a miracle of economy he might pay it out of his salary at the end of the week. Consequently, he dined out two or three days: at least he did not dine at home; but his dissipation did not seem to agree with him, for he looked white and tired. Luckily, he had not to pay for his lodgings till Mrs. Bryant came back, and he sincerely hoped that the good lady would be happy with her sister, Mrs. Smith, till his finances were in better order. When he got his money he lost no time in settling Mr. Robinson's little account, and was fortunate enough to intercept another, about which Mr. Brett the tailor was growing seriously uneasy. He would not for the world have parted with the precious document, but he began to wonder how he should extricate himself from his growing embarrassments. Lydia—half suspicious, half laughing—made a remark about his continual absence from home. "You are getting to be very gay, ain't you, Mr. Thorne?" she said; and she pulled her curl with her old liveliness, and watched him while she spoke.

"Well, rather so: it does seem like it," he allowed.

"I think you'll be getting too fine for Bellevue street," said the girl: "I'm afraid we ain't scarcely smart enough for you already."

Had she any idea how much he was in their power? Was this a taunt or a chance shot?

"Oh no, I think not," he said. "You see, Miss Bryant, I'm used to Bellevue street now. By the way, I shall dine out again to-morrow."

"What! again to-morrow?" Lydia compressed her lips and looked at him. "Oh, very well: it is a fine thing to have friends make so much of one," she said as she turned to leave the room.

Percival came home late the next evening. As he passed Judith's sitting-room the door stood wide and revealed its desolate emptiness. Was she gone, absolutely gone? And he had been out and had never had a word of farewell from her! Perhaps she had looked for him in the middle of the day and wondered why he did not come. Down stairs he heard Lydia calling to the girl: "Emma, didn't I tell you to put the 'Lodgings' card up in the windows as soon as Miss Lisle was out of the house? It might just as well have been up before. What d'ye mean by leaving it lying here on the table? You're enough to provoke a saint—that you are! How d'ye know a score of people mayn't have been looking for lodgings to-day, and I dare say there won't be one to-morrow. If ever there was a lazy, good-for-nothing—" The violent slamming of the kitchen-door cut off the remainder of the discourse, but a shrill screaming voice might still be heard. Percival was certain that the tide of eloquence flowed on undiminished, though of articulate words he could distinguish none. It is to be feared that Emma was less fortunate.

It was true, then. Judith was gone, and that without a farewell look or touch of the hand to mark the day! They had lived for months under the same roof, and, though days might pass without granting them a glimpse of each other, the possibility of a meeting was continually with them. It was only that night that Percival, sitting by his cheerless fireside, understood what that possibility had been to him. He consoled himself as well as he could for his ignorance of the hour of Judith's departure by reflecting that Lydia would have followed her about with malicious watchfulness, and would either have played the spy at their interview or invented a parting instead of that which she had not seen. "She can't gossip now," thought Percival.

Meanwhile, Lydia perceived, beyond a doubt, that they must have arranged some way of meeting, since they had not taken the trouble to say "Good-bye."

[TO BE CONTINUED.]

THE HARVESTING-ANTS OF FLORIDA

IN the low pine barrens of Florida are large districts thickly dotted over with small mounds made by a species of ant whose habits are unknown to the scientific world. Each mound is surrounded by a circle of small chips and pieces of charcoal, which the busy inhabitants often bring from a long distance. The hills are regular in outline, with a crater-like depression on the summit, in the centre of which is the gateway or entrance.

These ants do not live in vast communities like the mound-builders of the North, but each hill seems to be a republic by itself, though separate colonies in the same neighborhood have friendly relations with each other. Their color is rufous or reddish-brown, and they are furnished with stings like bees and wasps, and, like the honey-bee, always die after inflicting a wound, for their stings are torn from their bodies and left in the victim. The pain inflicted is about the same as that caused by the sting of the honey-bee. But they are not as vicious as most stinging insects: they will submit to considerable rough treatment before resorting to this last resource.

There are three sets of neuters in each colony—major and minor workers and soldiers: also one wingless queen is found in each nest. The head is very large, especially that of the soldier.¹ The workers minor—which are the true workers—have regular well-defined teeth on the mandibles, while most of the soldiers have merely the rudiments or teeth entirely obsolete. All the queens which I have found—eighteen in number—have perfectly smooth mandibles, without the least vestige of a tooth.

Early in December, 1877, I brought a large colony of these ants from one of the hills, including the workers major and minor and soldiers, and established them in a glass jar which I placed in my study. They very soon commenced work, tunnelling the earth and erecting a formicary, as nearly as they could after the pattern of their home on the barrens. The mining was done entirely by the small workers. At first they refused all animal food, but ate greedily fruit and sugar, and all kinds of seeds which I gave them were immediately taken below, out of sight. I now visited the mounds on the barrens and found abundant indications of their food-supplies. At the base of each mound was a heap of chaff and shells of various kinds of seeds. The chaff was Aristida speciformis, which grew plentifully all about. I also found many seeds of Euphorbia and Croton, and several species of leguminous seeds. But the ants were not bringing seeds in at this time of year: they were only carrying out the discarded seeds and chaff; and only on the warmest days were they very active. But they do not wholly hibernate. Even after a frosty night, by ten o'clock in the morning many of the hills would be quite active.

SOLDIER.

I sent specimens to the Rev. Dr. McCook of Philadelphia to be named, and he identified them as Pogono myrmex crudelis, described by Smith as Atta crudelis² Dr. McCook predicted from their close structural resemblance to the Texan "agricultural ant" that they would prove to be harvesting-ants.

On excavating a nest I found chambers or store-rooms filled with various kinds of seeds. But, so far as I have observed, the seeds are not eaten until they are swollen or sprouted, when the outer covering bursts of itself. At this stage the starch is being converted into sugar, and this seems to be what the ants are after. They also seemed to be very fond of the yellow pollen-dust of the pine. The catkins of the long-leaved pine (Pinus australis) commenced falling in February, and I noticed ants congregated on them; so I took those just ready to discharge the pollen, and shook the dust on the mound in little heaps, which were soon surrounded by ants, crowding and jostling each other in their eagerness to obtain a share.

The colony in the glass jar seemed perfectly contented, not trying to make their escape at all. The earth was originally a little more than two inches in depth, but by the first of February these wonderful architects had reared their domicile to the height of six inches. They raised tier upon tier of chambers in so substantial a manner that they never fell in. One of the store-rooms in which they deposited the seeds I gave them was at the bottom of the jar, and the seeds were stored against the glass with no intervening earth between: it contained about a teaspoonful of millet. I gave this chamber the right degree of heat and moisture to sprout the seed by pouring a little water down the side of the jar until it penetrated the chamber, and then setting it near the fire. The ants soon appreciated the condition of this store-room, and many congregated there and seemed to be enjoying a feast. The next day the seeds were all brought to the surface and deposited in a little heap on one side of the jar, where many of them grew, making a pretty little green forest, which the ants soon cut down and destroyed. This chamber remained empty for three or four days, and was then again refilled with fresh millet and apple and croton seeds.

I kept a small shell, which held about a tablespoonful of water, standing in the jar for the ants to drink from. For more than a month the water was allowed to remain clear, the ants often coming to the edge to drink; but one day one was walking on the edge of the shell, and carrying an apple-seed, when she lost her footing and rolled into the water. She floundered about for a few moments, still holding on to the seed: at last she let it drop and crawled out. As soon as she had divested herself of the surplus water, she consulted several of her companions, and they immediately went to work and filled up the shell, first throwing in four or five apple-seeds, and then filling in with earth; and ever after, as often as I cleared out the shell and put in fresh water, it would be filled with earth, sticks and seeds; and they now served all sweet liquids which I gave them in the same way, sipping the syrup from the moistened earth.

Like other ants, they are very fastidious about removing their dead companions. I buried one about half an inch beneath the soil. Very soon several congregated about the spot and commenced digging with their fore feet, after the manner of digger-wasps, throwing the earth backward. They soon unearthed and pulled the body out, when one seized and tried to remove it, climbing up the side of the jar, and falling back until I relieved her of the burden.

From time to time I add new recruits of soldiers and workers to the jar. This always causes a little confusion for a few moments: there is a quick challenging with antennæ, but no fighting, and soon all are working harmoniously together. I found three half-drowned, chilled ants near the mound from which most of the inhabitants of the jar were taken. One was not only wet and chilled, but also covered with sand. These I put on a small leaf and placed in the centre of the jar. The genial warmth soon revived them. Many of their old companions clustered around them, and there seemed to be considerable consultation. The two wet ants were soon made welcome, and, leaving the leaf, were conducted by their comrades—from whom they had been separated for more than two months—to the rooms below. But the one covered with sand—a major—did not meet with so kindly a reception. She still remained on the leaf trying to cleanse herself. All the ants had left her save one, who was determined to quarrel with her. I removed this one, and now another came up, bit at her and annoyed her until I removed this one also. Then some half dozen congregated about the leaf, touching her with their antennæ and walking round her. By this time she was nearly free from the sand, and was looking quite bright, strutting about the leaf in a threatening attitude, with her mandibles wide apart. She was not attacked by these last inspectors, though still looked upon a little suspiciously. I then returned the two quarrelsome ants: they immediately walked up to their unfortunate comrade, and now seemed to be satisfied that she was a respectable ant, and admitted her into the community with no further challenging.

1. WORKER MAJOR.

2. OUTLINE OF HEAD OF WORKER MAJOR.

3. OUTLINE OF BODY OF WORKER MINOR.

I found a nest of large carpenter-ants (Camponotus atriceps, var. esuriens, Smith) which had made their home in fallen timber. Upon examining their work, it was evident they must have strong tools to work with, for the numerous rooms and chambers of their domicile were often made in firm, hard wood. They are the largest, most vicious species I have ever seen. I introduced one of these terrible creatures into the jar among the quiet, peaceful occupants. A large worker major immediately closed with her: it was so quickly done that I could not tell which was the attacking party. They rolled about a few moments in a close embrace, till they rolled out of sight through the wide entrance to one of the rooms below. There was considerable excitement and increased activity among the workers, who were constantly bringing to the surface bits of earth which the struggling warriors had loosened. In about an hour the head of the carpenter was brought out, divested of every member: both the antennæ and palpi were gone, cut close to the head. A little later the abdomen was brought out, and still later the thorax with not an entire leg left.

QUEEN: SIDE-VIEW, SHOWING PECULIAR CONFORMATION OF THE THORAX.

Several times during the months of January and February I introduced into the jar a number of half-grown larvæ of the harvester. Without any hesitation they were quickly carried to the rooms below by the workers minor. On the 4th of February I found a large number of the larvæ of the carpenter-ant (Camponotus meleus, Say). They were very small, and closely packed together in a chamber cut out of hard wood, two inches in length and an inch and a quarter in diameter, nearly circular. It was packed full of larvæ and eggs, the larvæ apparently just hatched. I detached a small mass, all stuck together, and placed them in the jar with the harvesters. The workers minor immediately surrounded the mass, touching it with their antennæ, and then retreated backward, passing their fore legs over the head and antennæ, as if the larvæ were obnoxious to them. Great commotion ensued, followed by an apparent consultation lasting a few moments; but soon the usual quietness reigned, and most of the ants left the helpless larvæ and returned to their mining and to the storing away of seeds or feeding their own young. But two or three had not entirely deserted the young carpenters. Again and again they touched them, and then retreated, cleansing the antennæ as they moved backward. At last one seized the mass and held it in her mandibles, standing nearly in an upright position. Several workers now surrounded her, picked the larvæ off, one by one, and carried them below, until all were separated and disposed of.

But by far the most satisfactory way of studying the ants is in their native haunts on the barrens, where I had ten nests under observation. One of these was so situated that it received the direct rays of the sun all day, and was protected from north and east winds by dense, low shrubbery. On sunny days, even with a cool wind from the north, when taking my seat in this sheltered spot, I would soon become uncomfortably warm. This hill was always active whenever I visited it, while in other localities the ants would often be all housed. Around this active nest I stuck stems of millet eighteen inches high, surmounted by the close-packed heads. The ants climbed the stems, loosened and secured the seeds, and stored them within the nest. They worked vigorously, sometimes twenty or more on one head pulling away at the seeds. In my artificial formicary they did not mount the stems, even when the heads were not more than three or four inches from the ground, but seeds that I scattered in the jar were always taken below.

I threw down a handful of apple-seeds near the entrance of the active hill on the barrens. This immediately attracted a large number of excited ants. They rushed to the seeds in a warlike attitude, and began carrying them off, depositing them two or three feet away. But as soon as the excitement caused by the sudden pouring down of the seeds had subsided, they seemed to comprehend that they had been throwing away good seeds; and now, changing their tactics, not only carried the remainder into the nest, but finally brought back and stored all those that had been thrown away.

On excavating the nests we found granaries of seed scattered irregularly throughout to the depth of twenty-two inches below the surface of the ground: some were near the surface, and a few sprouted seeds were scattered about in the mound. The mound is usually not more than four to six inches above the level of the ground.

The great majority of nests that I have found are in the low pine barrens—so low that on reaching the depth of two feet the water runs into the cavity like a spring, and stands above some of the granaries. Notwithstanding this wet locality, I found no sprouted seeds in the deeper store-rooms, but only in the warmer mound. On sunny days the larvæ are brought up into the mound and deposited in chambers near the surface, where they receive the benefit of the sun's rays. On cool, cloudy days and in the early morning I found no larvæ near the surface. If the ants are intelligent enough to treat the larvæ in this way, why should they not store seeds where they will not sprout? And when they need to sprout them in order to obtain the sugar they contain, it would take no more wisdom to treat the seed as they do the larvæ—bringing them near the surface to obtain the right degree of heat for the required result.

The little workers seem very determined not to allow any green thing to grow on their mounds. Cassia and croton and many other plants start to grow from seeds which the ants have dropped, but they are always cut down and destroyed if too near the mound, though allowed to grow at a little distance; so that a botanist would be astonished at the great variety of plants within a small area if not aware of the source from which they came. I sometimes found small shrubs of Kalmia hirsuta and Hypericums entirely dead on the mounds, the roots completely girdled in many places. It is very amusing to watch them in their efforts to destroy grass and other plants. Their determined persistence is remarkable: they cut off the tender blades and throw them away. But they do not stop here: the roots must be exterminated; so several dig around the plant, throwing the earth backward, and after making it bare they cut and girdle the roots until the plant is killed.

1. With well-formed teeth.

2. Partially developed.

3. Entirely obsolete.

MANDIBLES OF THE HARVESTING-ANT.

Early in March the ants in the jar seemed to have completed their domicile. At first, several chambers were visible through the glass, and the galleries leading to them, but gradually the light was all shut out by placing little particles of earth against the glass, thus depriving me of the opportunity of watching their movements within the nest. So I now took the jar to the barrens, and set it by the side of a nest which was about a mile distant from where most of the ants were obtained. Here I carefully broke it, and took the thin shell of glass from around the nest, which did not fall, but stood six inches in height and eighteen inches in circumference. With a large knife I removed a thin layer of earth, which revealed three admirable chambers with galleries leading from one to the other. Immediately below there were five chambers well filled with ants, and below these other chambers were scattered irregularly throughout, with only thin partitions between.

At various times I had given the ants moistened sugar on the thick curved leaves of the live-oak, and several of these had been covered while the ants were making their excavations. Two of the leaves were three inches below the surface, and the ants had utilized them by making the inner curved surface answer for the floor and sides of fine chambers; and here a large number of ants, both soldiers and workers, were crowded together. In other chambers I found the larvæ, which were greatly increased in size since I had placed them in the jar; and the larvæ of the carpenter-ant were being reared, as I found some smaller than any I had introduced belonging to the harvester.

Very soon a great crowd of excited ants came from the hill near which I had broken the jar, and began to transport the larvæ, and also the mature ants, to their own dominions. There was no fighting: the ants from the jar submitted to being carried, not offering the least resistance. A small worker would often take hold of a large soldier, sometimes pushing, sometimes dragging, her through the sand, and she would be as quiet as if dead or dying; but if we touch the little worker she leaves her burden and rushes about to see what the interference means; and now the soldier straightens up, as bright and lively as the rest, and after passing her fore legs over her head and body, goes of her own accord into the new nest, meeting with no opposition. Some of the ants would coil up and allow themselves to be carried easily. Others were led along by an antenna or a leg, in either case manifesting no resistance. For three hours I watched the proceeding, and could see no fighting. It looked precisely as if the inhabitants of the jar realized their helpless condition, and gladly submitted to be taken prisoners or to become partners with this new firm.

I left them, and after the lapse of two hours again visited the spot. The seeds that had been in the jar were now being transferred to the other nest, and two new entrances at the base of the mound were being made. And now every little while an ant would be ejected from the nest. One worker would bring another out and lay her down, often not more than three inches away from the door, but, so far as I could see, she was in no wise injured. Her first movement was to make herself presentable by passing her fore legs over her head and body: as soon as this was completed she returned within the nest. But there was one large soldier which the whole community seemed combined against. She was led or dragged away from the entrance of the nest eight times, and each time left at the base of the mound among the rubbish. Sometimes she was led or carried by one alone, sometimes two or three would conduct her, and then leave her, when she would at once proceed to make her toilet; which completed, she would again return to the door of the nest, when she would be again conducted away, offering no resistance. I now picked her up, which made her very fierce. She seized my glove with her powerful mandibles, and held on with a persistency equal to the most vicious species, at the same time trying to use her sting. As soon as I could free her from the glove I secured her, and on reaching home placed her under the microscope, and found she was not injured and had strong teeth in her mandibles.

On the next day I returned her to the nest, and again she was met by the indignant police at the door and conducted away. With her strong mandibles she could have crushed any number of her small assailants, but in no instance did she show the least disposition to rebel against the indignities to which she was subjected. She was often dragged away with her back on the ground and her legs coiled up, apparently helpless. If all the soldiers had been treated in this way, it would not have been so remarkable, but so far as I could see the rest were allowed to remain, going in and out of the nest as if taking a survey of their new surroundings.

For five months I had these ants under almost constant observation, and yet I was unable to make out the true position of the soldiers in the colony. They stay mostly within the nest. On the warmest days a few will come out and walk leisurely around the mound. They are not scattered irregularly through the nest, but seem to be housed together in large chambers. In one of these chambers I found a wingless queen in their midst. It seemed very fitting for a queen to be surrounded by Amazon soldiers; but, alas! they seemed more like maids of honor than soldiers, for they forsook the royal lady without making an effort to defend her. Not so, however, with the little workers: they rallied around her, ready to guard her with their lives, and no doubt would have succeeded had it been any ordinary foe.

This phenomenon—the soldiers and queens with smooth mandibles—is very puzzling, and has excited much interest among naturalists both in this country and in Europe. I sent specimens to Mr. Charles Darwin, which he forwarded to Mr. Frederick Smith of the British Museum (who, Mr. Darwin informs me, is the highest authority in Europe on ants and other Hymenoptera). Mr. Smith says: "Your observations on the structural differences in the mandibles of this ant are quite new to me." I also sent specimens to the eminent naturalist Dr. Auguste Forel of Munich, who, like Mr. Smith, had never observed this feature of the mandibles in any ant; but he has a theory to account for it—that the smooth mandibles have been worn down by labor. If this theory is true, how can we account for the fact that other ants do not wear down their teeth? The chitinous covering of this harvesting-ant is firm and hard. The stage forceps of my microscope closes with a spring, and in studying this ant I have put thousands of individuals to the test, holding them in the forceps to examine their mandibles, and in no instance do I recollect seeing one injured, while many other species are easily injured by the forceps. Among these are the two large species of carpenter-ant before mentioned, which work in stumps or fallen timber. These ants all have well-developed teeth, and the shell-like covering enveloping the body is much thinner than that of the harvesting-ant.

If it be urged that hard wood will not wear down the teeth like mining in the sandy soil, I can bring forward another member of this family (Camponotus socius, Roger), which lives in the ground, and whose mining and tunnelling are on a much more extensive scale than those of the harvesting-ant. The formicary of this Camponotus often extends over several square rods, with large entrances at various points, all connected by underground galleries, requiring a great amount of labor to construct them; while each colony of the harvesting-ant has a close, compact nest or formicary, requiring much less work to construct it. The worker major of Camponotus socius is very large—larger than the soldier of the harvesting-ant. The formicaries of the two species are often in close contact, so that the nature of the soil is precisely the same. I have examined thousands of Camponotus socius, and in no instance have I found the teeth worn down.

There is still another difficulty in the way of Dr. Forel's theory. Careful observations have revealed the fact that all the harvesting-ants that engage in work of any kind are armed with teeth. I took thirty soldiers with smooth mandibles, put them in a glass jar with every facility for making a nest, but they refused to work, scorned all my offers of food, and remained huddled together for three days. I then introduced several workers minor, and they immediately commenced tunnelling the earth and making chambers, into which the lazy soldiers crawled, meeting with no opposition from these industrious little creatures. My experiments did not stop here. I now took about a hundred specimens—soldiers and a few workers major, the last with partially-developed teeth—and placed them in a jar. Some of these made feeble attempts to construct a nest, but they did not store away seeds, and larvæ which I put in the jar they carried about as if not knowing what to do with them.

There is every appearance of an aristocracy among these humble creatures. The minors are the servants who do the work, while the queens and soldiers (especially the soldiers, which more nearly approach the queen in shape of head and mandibles) seem to live a life of comparative ease, and have their food brought to them by the minors. This may be the reason of the non-development of the teeth among the aristocracy. But how the same parent can produce such differing offspring—some born to a life of ease, with obsolete teeth, and others with well-developed teeth to do the work—is one of the mysteries in Nature. The only way to settle the point with regard to the mandibles beyond dispute is to find the pupæ of very young queens and soldiers, which I was unable to do during my stay in Florida. All the young were in the larval state.

Mary Treat.