494 J. C. BRANNER — GEOLOGIC WORK OF ANTS 



and I am unable to say how large an area the contents can properly be 

 distributed over, how long the termites were in doing the work, or how 

 large the colonies were that made them. 



In the case of the white ants, the earth undergoes some process of 

 digestion and passes through the bodies of these insects, so that the chem- 

 ical effect is probably more important than the mere upturning it gets 

 from the true ants. 



0RQA2JIC MATTER 



The true ants carry into their burrows enormous quantities of leaves 

 and other organic matter. These leaves must yield either directly or in- 

 directly organic acids, which help attack the soil, the minerals, and the 

 rocks with which they come in contact. 



The organic matter carried into their burrows by the termites consists 

 chiefly of the decayed wood and other vegetation eaten by them. These 

 materials, however, can not fail to contribute organic acids that help 

 attack the minerals of the soil and adjacent rocks. 



OPENINGS IN TEE SOIL 



The extensive subterranean excavations, especially those of the true 

 ants, permit the freer circulation of atmospheric air and of carbon diox- 

 ide. These channels must also serve from time to time for the passage 

 of meteoric waters, and their great extent and ramification must hasten 

 very considerably all the processes of atmospheric disintegration and 

 alteration of soils, minerals, and rocks. 



Unfortunately we have no observations at present that enable us to 

 give quantitative values to these underground agencies and activities. 

 We only know that the openings beneath the surface are rudely equal to 

 the amount of soil in the above-ground structures. 



Eesume 



Ants and termites are vastly more numerous in tropical America than 

 they are in the temperate regions. 



They show a marked preference for, or rather their structures stand 

 up better on, clayey than on sandy soil. 



They affect the geology, especially the soil and subsoil, both directly 

 and indirectly. 



Directly : 



1. By their habits of making underground excavations that 

 radiate from a central nucleus and often aggregate several 

 miles in length. 



