ants' nests. 373 



heaps of the large ants and devour them from underneath without 

 being seen, thanks to their small size. They also devour openly 

 the forage supplies, as well as the dead and sick individuals, of 

 the larger species (mostly Formica fusca^ L., but also Formica rufa^ 

 F. pratensis, F. sanguinea, Polyergus rtifescefis, Lasius niger, etc.) 



Fig. 6 represents a fragment of a double nest of Fontiica fusca 

 and Solenopsis fugax from the Zurich Mountain. By means of 

 dissolved shellac, which I poured upon the nest in fine weather, 

 and then allowed to dry, I succeeded in making it firm enough to 

 be able to take it out without injuring it. The fine-grained, 

 polished interior walls of the Solenopsis cavities are seen, in con- 

 trast to the coarse-grained and more spacious Formica chambers. 

 As the ants take up the moist earth with their mandibles in the 

 form of small lumps, and then work it into shape with their jaws 

 and forelegs, in order to construct their masonry with it, and as, 

 moreover, the large Formica works with much coarser particles 

 than the puny Solenopsis^ the different character of the walls is 

 at once explained. 



I have already explained the frequent occurrence of imperfect, 

 more accidental compound nests of other species of ant, by 

 ascribing them to the acquisition of favourable localities, especially 

 the underside of stones. From this competition frequently arise 

 very murderous underground wars, which I have often watched. 

 I have noticed closely, in glass apparatus, how they are carried on. 

 The ants mine toward each other. A battle begins where their 

 work happens to meet. The conqueror forces his way into the 

 gallery of the conquered.* The latter, however, hastens, after he 

 has retired a few millimetres or centimetres, as the case may be, to 

 stop up his gallery thoroughly with earth. The victor does not 

 then, by any means, always succeed in again finding the entrance 

 to it, but, in many cases, mines by the side of it, and thus partial 

 interlappings of the nests arise, The galleries of Sole?iopsis fugax 

 are often broken through by the large ants. The little robbers are, 

 however, in the first place, very courageous and combative ; and, 

 in the second place, they know how to mine rapidly and how to 

 barricade rapidly, and by this means to make a skilful use of all 

 the partitions, as I have been enabled to observe directly in the 

 glass nest. The digging and fighting spirit is at its highest pitch 



International Journal of Microscopy and Natural Science. 

 Third Series. Vol. VII. a a 



