THE FOUXDIXG OF COLOXIES BY ATTA SEXDENS." 



By Dr. Jakob Hxjber (Para). 



A study of the fungiis-cultivating ants belonging to the genus Atta 

 is undoubtedly one of the most attractive subjects of biolog}^, and 

 affords a number of highly interesting i3roblems to both zoologists 

 and botanists. From the time of Holler's classical investigations, 

 proving the truth of Belt's theories, there has remained no further 

 doubt that the species of this genus Atta maintain with marvelous 

 understanding and skill pure cultures of fungus masses {Rozites 

 gongylophora) ^ and incite upon these, by influences not yet under- 

 stood, the growth of the so-called "' kohlrabi " structures, peculiar 

 hyphae swellings, with which they feed themselves and their young. 

 Holler's investigations, known so widely as to need no special refer- 

 ence here, are concerned exclusively with definite ant colonies of 

 numberless workers and in many apartments, but in respect to the 

 founding of new colonies he has done no investigating. 



The way in which a new colony, together with its fungus garden, 

 is brought into existence has therefore remained to the present time 

 a mystery, and although many valuable discussions upon the true 

 solution of the problem have appeared they have failed to present a 

 satisfactory answer to the difficulties. As earlj^ as 1894 A. G. 

 Sampoi'o de Azevedo, an observant Brazilian amateur, published 

 some valuable observations on the founding of colonies of Atta 

 sexdens in his rather untrustworthy brochure, Saiiva on Manhiiuara 

 (Sao Paulo, 1894). This investigator dug up a female Atta ten days 

 after the mating period, and discovered in the underground compart- 

 ment two small white mounds, one consisting of 50 to 60 eggs, the 

 other of a filamentous mass — the young fungus garden — which, how- 

 ever, Sampoio failed to recognize as such. Three and a half months 

 after the nuptial flight he dug open a nest, the gallery of exit to 

 which had been already opened. Within were numberless workers 

 of three different sizes, all, however, somewhat smaller than those in 

 established colonies. These were eiigaged in leaf cutting and in con- 



a Translation, by permission, of Uber die Koloniengriindung bei Atta sex- 

 dens, von Dr. Jakob Huber (Para), in Biologisches Ceutralblatt, Bd. XXV, 1905, 

 pp. 606-619, 624-635, Leipzig. Yerlag von Georg Tbieme. 



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