BLACK ANTS 



sists in their knowing how to carry on two contrary opera- 

 tions, mining and building, at the same time, and how to 

 make the one subservient to the other. 



What is still more singular, they display the same genius 

 in excavating as in building above-ground. The moisture 

 which penetrates to the bottom of their nest is doubtless of 

 great assistance to them in their labour. 



The black ants, Formica fusca, build in a manner very 

 different from the brown ants. We have already seen from the 

 description of their dwelling that it is exceedingly simple 

 and heavy in its construction as compared with the latter, 

 but its simplicity was favourable to the object I had in view 

 of examining, if possible, how many ants could work together 

 intelligently on the same design, and of discovering whether 

 they acted independently, or helped one another; of their 

 own accord, or from some general impulse. 



I do not flatter myself that I have solved these important 

 questions, but the facts I am about to describe will at all 

 events throw some light on the subject. 



When the black ants wish to add to the height of their 

 dwelling, they begin by placing over the roof a thick layer 

 of earth, which they bring from the interior, and in this 

 they trace the plan of a new story in low relief. 



They first hollow out here and there, more or less close to 

 each other, little dykes of a breadth proportioned to the use 

 for which they are intended, and all of very nearly the same 

 depth; the masses of earth left between them afterwards 

 serve for the foundation of the inner walls, so that when the 

 useless earth has been removed from the bottom of each 

 chamber and the foundation of the walls reduced to a 

 proper thickness, all the architects have to do is to increase 

 the height of the building and build a roof over the apart- 

 ments. 



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