488 ants' nests. 



. The mound is gradually enlarged aud strengthened by materials 

 dragged to it. It protects the interior perfectly against cold and rain. 



Formica rufa i. sp. of the fir woods uses chiefly lir leaves; Formica 

 pratensis of the meadows builds flatter mounds and uses more iiieces 

 of wood and blades of grass, pieces of dry branches, etc.; Formica 

 exseeta uses more particles of dry leaves, etc.; Formica sanf/idnea 

 Latr. builds mounds composed of the above-mentioned materials and 

 earth; its work is partly that of a carpenter and partly masonry; the 

 latter, however, which is executed by the "slaves" [Formica fusca), 

 usually prevails. 



It is impossible for us to describe everything, and we refer our 

 readers to Huberts admirable description of the way in which the forest 

 ants and the earthen-mound ants build their nests. It may well be 

 said that almost every species — either in earthen structures, in wood 

 uests, or in combined structures — has its peculiarities with regard to 

 the quality of the material, the fineness of the grain, the shape and 

 arrangement of the mound and the labyrinth, the comparative thick- 

 ness of the walls, the size of the chambers, etc., so that the species 

 may frequently be known by the structure. 



Still the ants often rob one another's nests, and this frequently 

 renders it difficult to recognize the architect. 



There are species, it is true, whose architecture can hardly be dis- 

 tinguished, as, for instance, the little species of Myrmica. 



5.— PASTEBOARD NESTS AND SPUN NESTS. 



I have already, in the Mittheilungen of the Swiss Entomological 

 Society, Vol. YIII, part 6, 1891, given some information with regard to 

 the singular nests which are now to occupy onr attention. A well- 

 known European species, Lasiiis fuUginosus Latr., builds peculiar 

 pasteboard nests, which Huber erroneously thought to be excavated in 

 wood, while Meinert, Mayr, and others, including myself, have demon- 

 strated their true nature beyond a doubt. They are composed of tlie 

 finest i^articles of wood dust or of earth and small stones, which, by 

 means of a viscous substance secreted by the ants, are worked up into 

 so strong a pasteboard (see Forel, Fourmis de la Suisse, \^\^. 181-187) 

 that the partitions between the excavations are extremelj' thin (as 

 thin as visiting cards). These nests are mostly found in hollow trees. 

 That they are not excavated, but are comi)Osed of pasteboard, I have 

 clearly shown by microscopic cuts. Meinert first called attention to 

 the fact that in LasiKsfidiginosus the glands of the upper jaw are 

 extraordinarily large, and conjectured that they are the glands which 

 secrete this viscous substance (cement). In facta comparative physio- 

 logical study of this gland which Wolff (" The smelling organ of 

 bees") erroneously designated asthesmelling-mucous gland, shows that 

 a discovery which has been misinterpreted by Wolff" is of sj^ecial value. 

 Tbe substance secreted by this gland, both in bees aud in ants, aud 



