474 J. C. BRANNER GEOLOGIC WORK OF ANTS j 



some of the main entrances to their colonies, and blew the fumes of sulphur 

 down the galleries by means of bellows. I saw the smoke issue from a great 

 number of outlets, one of which was 70 yards distant from the place where 

 the bellows were used. This shows how extensively the underground galleries 

 are ramified." 



Another writer, Eev. J. C. Wood, tells of the sauhas having 



"ruined a gold mine for a time, breaking into it with a tunnel some 80 yards 

 in length and letting in a torrent of water, which broke down the machinery 

 and washed away all the supports, so that the mine had to be dug afresh."" 



The diameter of an Tindergronnd passage varies from 1 or 2 centi- 

 meters up to 5 centimeters or more. They widen out and narrow down 

 without any apparent reason, and those made by the sauhas that have 

 been examined have here and there local enlargements that are com- 

 monly from 1 to 2 decimeters in height and from 1 to 3 decimeters in 

 length. These chambers, when freshly opened, I have generally found 

 filled, or partly filled, with loose, mouldy masses of dead leaves. 



Belt describes the underground passages in Nicaragua as follows :^^ 



"In our mining operations we also, on two occasions, carried our excavations 

 from below up through very large formicariums, so that all their underground 

 workings were exposed to observation. I found their nests below to consist of 

 numerous rounded chambers, about as large as a man's head, connected to- 

 gether by tunneled passages leading from one chamber to another." 



RELATIONS TO THE SOIL 



The distribution of ant colonies as shown by their mounds suggests, if 

 it does not prove beyond question, that the character of the soil has an 

 important infiuence on the distribution of the ants themselves. In view 

 of the habits of ants, it seems highly probable that at the time of leaving 

 their nests the young females scatter over the surrounding region prettv 

 much at random.' When they alight, some of them find themselves in 

 locations where ant colonies, on account of the character of the ground, 

 can not possibly survive, and as these young females break off their wings 

 as soon as they alight, they can not renew their flight and seek more 

 favorable ground, but they must perish without having founded a new 

 colony. And this must happen over and over again, with the final result 

 that localities unfavorable for ants do not have ant colonies, while the 

 favorable localities may have a superabundance of them. Favorable and 



35 Charles Waterton : Wanderings In South America. Explanatory Index, Rev. J. G. 

 Wood, p. 47. London, 1882, 



38 The Naturalist in Nicaragua, p. 80. 



