I could never satisfy myself as to the function of these worker-majors.They are not the soldiers or defenders of the working portion of the community, like the armed class in the termites, or white ants, for they never fight.The species has no sting, and does not display active resistance when interfered with.Ionce imagined they exercised a sort of superintendence over the others; but this function is entirely unnecessary in a community where all work with a precision and regularity resembling the subordinate parts of a piece of machinery.I came to the conclusion, at last, that they have no very precisely defined function.They cannot, however, be entirely useless to the community, for the sustenance of an idle class of such bulky individuals would be too heavy a charge for the species to sustain.I think they serve, in some sort, as passive instruments of protection to the real workers.Their enormously large, hard, and indestructible heads may be of use in protecting them against the attacks of insectivorous animals.They would be, on this view, a kind of "pieces de resistance," serving as a foil against onslaughts made on the main body of workers.
The third order of workers is the most curious of all.If the top of a small, fresh hillock, one in which the thatching process is going on, is taken off, a broad cylindrical shaft is disclosed at a depth of about two feet from the surface.If this is probed with a stick, which may be done to the extent of three or four feet without touching bottom, a small number of colossal fellows (Fig.3) will slowly begin to make their way up the smooth sides of the mine.Their heads are of the same size as those of the class Fig.2, but the front is clothed with hairs, instead of being polished, and they have in the middle of the forehead a twin, ocellus, or simple eye, of quite different structure from the ordinary compound eyes, on the sides of the head.This frontal eye is totally wanting in the other workers, and is not known in any other kind of ant.The apparition of these strange creatures from the cavernous depths of the mine reminded me, when I first observed them, of the Cyclopes of Homeric fable.They were not very pugnacious, as I feared they would be, and I had no difficulty in securing a few with my fingers.I never saw them under any other circumstances than those here related, and what their special functions may be I cannot divine.
The whole arrangement of a Formicarium, or ant-colony, and all the varied activity of ant-life, are directed to one main purpose--the perpetuation and dissemination of the species.Most of the labour which we see performed by the workers has for its end the sustenance and welfare of the young brood, which are helpless grubs.The true females are incapable of attending to the wants of their offspring; and it is on the poor sterile workers, who are denied all the other pleasures of maternity, that the entire care devolves.The workers are also the chief agents in carrying out the different migrations of the colonies, which are of vast importance to the dispersal and consequent prosperity of the species.The successful debut of the winged males and females depends likewise on the workers.It is amusing to see the activity and excitement which reigns in an ant's nest when the exodus of the winged individuals is taking place.The workers clear the roads of exit, and show the most lively interest in their departure, although it is highly improbable that any of them will return to the same colony.The swarming or exodus of the winged males and females of the Sauba ant takes place in January and February, that is, at the commencement of the rainy season.They come out in the evening in vast numbers, causing quite a commotion in the streets and lanes.They are of very large size, the female measuring no less than two-and-a-quarter inches in expanse of wing; the male is not much more than half this size.They are so eagerly preyed upon by insectivorous animals that on the morning after their flight not an individual is to be seen, a few impregnated females alone escaping the slaughter to found new colonies.
At the time of our arrival, Para had not quite recovered from the effects of a series of revolutions, brought about by the hatred which existed between the native Brazilians and the Portuguese;the former, in the end, calling to their aid the Indian and mixed coloured population.The number of inhabitants of the city had decreased, in consequence of these disorders, from 24,500 in 1819, to 15,000 in 1848.Although the public peace had not been broken for twelve years before the date of our visit, confidence was not yet completely restored, and the Portuguese merchants and tradesmen would not trust themselves to live at their beautiful country houses or rocinhas, which lie embosomed in the luxuriant shady gardens around the city.No progress had been made in clearing the second-growth forest which had grown over the once cultivated grounds, and now reached the end of all the suburban streets.The place had the aspect of one which had seen better days; the public buildings, including the palaces of the President and Bishop, the cathedral, the principal churches and convents, all seemed constructed on a scale of grandeur far beyond the present requirements of the city.Streets full of extensive private residences, built in the Italian style of architecture, were in a neglected condition, weeds and flourishing young trees growing from large cracks in the masonry.
The large public squares were overgrown with weeds and impassable, on account of the swampy places which occupied portions of their areas.Commerce, however, was now beginning to revive, and before I left the country I saw great improvements, as I shall have to relate towards the conclusion of this narrative.
