tunity to escape to the alpine stations of New Zealand or Australia, or to occupy the subantarctic islands.

The conclusion is therefore drawn that the land link was maintained during the period of refrigeration, and that from the Antarctic focus first the subtropical, then the temperate, lastly the alpine forms were expelled, each to gain a fresh footing in lower latitudes.

Possibly associated with the formation of great ice masses, a paroxysm of diastrophic energy ensued. This, which perhaps has not yet subsided, effected the destruction of the antarctic bridge, and to it may be due the recent disarticulation of the Dominion of New Zealand and the severance of Tasmania from its parent continent.

In the long perspective of past time Antarctica appears to fade and form like a summer cloud, now extending a limb, now shedding it, now resolving into a continent, now dissolving into an archipelago. At present it lies dead and cold under its white windingsheet of snow. By the light of the magician's lamp we watch the summer of the cycles dawn. The glow of life returns, the ice mask melts, green spreads a mantle. At last a vision comes of rippling brooks, of singing birds, of blossoming flowers, and of forest glades in the heart of Antarctica.

THE ANTS AND THEIR GUESTS.1

By P. E. WASMANN, S. J.,

Ignatius College, Valkenburg, Holland.

[With 10 plates.]

One hundred years of biological investigation of ants have passed since, in 1810, the Genevan Peter Huber published his "Recherches sur les mœurs des Fourmis indigènes." Therefore, since we celebrate this year a centenary of ant biology, let us first briefly review the development of myrmecology. Its character is a truly international one, in that investigators of the most distinct countries and nations have participated in it.

The classification of ants, already founded by Latreille, received a new impetus through Gustave Mayr about the middle of the previous century. Toward its completion August Forel, Carlo Emery, Ernest André, W. M. Wheeler, Ruzsky, Santschi, and others have distinguished themselves, so that we now know more than 5,000 species and subspecies, living and fossil, in this family. The anatomy of ants has been greatly advanced through the older works of Meinert, Forel, etc., and particularly through the numerous publications of Charles Janet. Recently one has turned also to the microscopic study of the development of the polar bodies within the eggs of ants. However, that which interests us most here is the development of bionomics, the knowledge of the behavior of ants.

The work of the father of biological ant study, Peter Huber, has been successfully continued by August Forel and later by Rudolf Brun in Switzerland, by Carlo Emery in Italy, by Sir John Lubbock (Lord Avebury) and recently by Horace Donisthorpe in England, by Gottfried Adlerz in Sweden, by Ernest André, H. Piéron, and most especially by Charles Janet in France, in North America by McCook, later on by Miss A. Fielde, Miss Buckingham, and through numerous important works by William Morton Wheeler, in Tunisia by F. Santschi, in Algeria by V. Cornetz, in Russia by Karawaiew, in Japan by M. Yano, in Brazil by H. v. Ihering, E. Goeldi, and G. Huber, in Germany by Viehmeyer, Escherich, and Reichensperger, in Belgium

1 Translated by permission from 1er Congrès International d'Entomologie, Bruxelles (August, 1910) Mémoires, vol. 2, pp. 209-232. With emendations and additions by the author.

by de Lannoy and Bondroit, etc. The names of those investigators who have especially distinguished themselves in separate branches of ant bionomics-the knowledge of the relation of ants to their guests, the study of the mode of foundation of the ant colonies, the development of social parasitism and of slavery, the investigations of the fungus gardens of the leaf-cutting ants, the construction of the nests of the highly interesting weaver ants, who use their larvæ as weaver's shuttles, etc. are much too numerous to make their separate mention possible in this brief space.

Through its rapid progress in all directions the modern study of ants has become on the one hand such a richly developed and richly ramified special science that it is no longer possible for the individual investigator to master the entire field. Division of labor, therefore, more and more took place, particularly also in the investigation of the myrmecophilous Arthropoda, which demands the collaboration of specialists in the most distinct classes and orders of arthropods.

On the other hand the bionomic science of ants, particularly, has stepped forth from the confines of a special science. Comparative psychology has in an increased measure turned its attention toward the psychological valuation of ant activities. The theory of descent has found among the ant guests a multitude of interesting proofs for the formation of new species, genera, and families of insects through adaptation to a myrmecophilous life. It has also found in the hypothetical phylogeny of social parasitism and of slavery among the ants one of the most instructive examples for the development of instinct. Social science has even made the attempt to find in the ant communities the prototypes for human social customs. But by all means it must be considered here that the ants, in spite of the great analogy which shows itself between many activities of their social instincts and human intellectual acts, are not miniature human beings. Scientific ant study has long ago withdrawn from the romanticism of humanization and sees in the wonderful accomplishments of the little ant brain instinctive activities, which, however, within certain limits, are plastically modifiable through sensory experiences of the individual. Science can therefore neither accept the ants as mere reflex machines nor as intellectual miniature humans. The truth with regard to the psychology of ants lies rather midway between these two extremes.

For lack of time I must unfortunately deny myself a more detailed development of all these highly interesting relations of ant biology, and must limit myself to placing before you, with the help of stereopticon pictures,1 some especially fascinating main points in the life of the ants and of their guests.

1 Qf the 40 photographic lantern slides of the lecture only a part is here reproduced.

1.-ORGANIZATION OF THE ANT SOCIETIES.

The simple ant colony represents a family in the narrower or wider sense. It comprises one or more generations of the descendants of one or more females of the same species of ant. The tribal mother is the fertilized queen, who has founded the colony. The descendants are in part wingless forms of the female sex, the so-called workers, in part young winged males and females, and in part also others, still young, though already fertilized and deälated, queens. The worker cast may again divide itself into different forms, namely, into true workers and into soldiers, which latter are distinguished from the workers by the prodigious structure of their heads or mandibles. Soldiers occur among our Palearctic ants only in a few genera (Colobopsis, Cataglyphis, Pheidole). The workers themselves can again divide into large and small individuals, of which the former are sometimes, as for example in Camponotus, veritable giants in comparison with the latter. This dimorphism is much further developed still in exotic genera, like Pheidologethon. In some species of ants there are found at the side of the winged females, which shed their wings only after pairing, wingless true females as well, the so-called ergatoid queens. A typical example of these, which was already known to Peter Huber, is offered by the amazon ant (Polyergus rufescens) (compare fig. 8a).1 In the tropical legionary and driver ants (Eciton and Dorylus) even wingless females alone occur, and moreover of relatively enormous size. In some species of ants there is even a manyfold pleomorphism of the females which finds expression in different transitions between females and workers. Much rarer are the wingless, and then mostly workerlike (ergatoid) males; they are known in but few species of ants, and occur either along with the normal winged males or as the only male form. An example of the last kind is shown in the shining guest ant, Formicoxenus nitidulus (fig. 1), where the males, on account of their great similarity to the workers, remained unnoticed 38 years, until Adlerz discovered them in 1884.

With many species of ants one can find several queens together in the same colony. With our hill ant, Formica rufa, their number in a single nest may even reach toward 100. Furthermore, an ant colony may possess several nests, which are simultaneously or alternately inhabited. So-called seasonal nests, which are changed according to the time of year, have been observed, for example, in Formica sanguinea and Prenolepis longicornis. By the plurality of queens in a single colony the ant states differ strikingly from the states of the honey bees. The latter bear by comparison more a monarchical, the former a republican character, since the queen with the ants forms

The figures 1 to 33 are arranged on plates 1 to 10.