880 THE BEGOLITH 



these stnictnres are numerous, as they are in certain districts 

 in the United States, by their constant deposits of matter on 

 the surface of the ground, they bury a good deal of vegeta- 

 ble waste in the soil, at the same time the animals are con- 

 stantly conveying into the earth large quantities of organic 

 matter which serves them as food, and the waste of this, 

 including the excreta of the animals themselves, is of con- 

 siderable importance in the refreshment of the soil." The geo- 

 logical efficacy of insects of this and other types is undoubtedly 

 greater in warmer climes, where not only are they found in 

 greater abundance, but their period of activity extends over a 

 larger portion of the year. Messrs. Mills and Branner, as al- 

 ready noted, are inclined to lay considerable stress on the work 

 of ants and termites in bringing about soil changes and rock 

 decomposition in Brazil. Branner states that in some parts of 

 the Amazon valley, of Minas Goyaz and Matto Grozzo, the soil 

 ^* looks as if it had been literally turned inside out by the bur- 

 rowing of ants and termites." The species popularly known 

 as saiihas excavate chambers and build galleries which are fre- 

 quently from 50 to 100 feet long, from 10 to 20 feet across, from 

 1 to 4 feet high, and contain tons of earth. The white ants or 

 termites, like the true ants, burrow extensive channels in the 

 ground, and build up huge nests upon the surface from the 

 size of which one may gain some idea of the extent of the under- 

 ground galleries. In the region extending from the state of 

 Parana to north of the Amazon and along the upper Paraguay 

 in Matto Grosso may be seen places where the nests are so close 

 together that one can almost walk upon them for several hun- 

 dred yards at a time, while no one of the nests is more than 10 

 feet from another over many acres of ground. Such vary in 

 size from 1 to 12 feet in height and 1 to 10 feet in diameter, and 

 do not seem to be confined to any particular kind of country, 

 though especially noticeable in the interior and timberless re- 

 gions. The constant transference of such quantities of soil from 

 below to the surface, and of organic matter from the surface 

 downward, cannot fail to bring about marked changes in its 

 physibal as well as chemical condition, while at the same time 

 affording passageways for air and meteoric waters, as already 

 noted.^ 



^In a later paper (Journal of Geology, Vol. 8, 1900) Prof. Branner de- 

 scribes the ant-hills, about Urucu station as ''so thick that the county looks 



